From 8cdb34a2996e1727b14c215266ff2f5def057f99 Mon Sep 17 00:00:00 2001
From: Ben Meadors <benmmeadors@gmail.com>
Date: Sun, 1 Jun 2025 15:54:54 -0500
Subject: [PATCH] Get rid of Arduino Strings

---
 src/graphics/Screen.cpp                       | 86 +++++++++++--------
 src/graphics/Screen.h                         |  6 +-
 src/graphics/draw/DebugRenderer.cpp           | 34 +++++---
 src/graphics/draw/NodeListRenderer.cpp        | 21 ++---
 src/graphics/draw/NodeListRenderer.h          |  2 +-
 src/graphics/draw/NotificationRenderer.cpp    | 42 +++++----
 src/graphics/draw/UIRenderer.cpp              | 44 +++++-----
 src/modules/CannedMessageModule.cpp           | 45 +++++-----
 src/modules/SerialModule.cpp                  | 70 +++++++++------
 src/modules/Telemetry/HealthTelemetry.cpp     | 25 ++++--
 src/modules/Telemetry/PowerTelemetry.cpp      |  8 +-
 src/modules/Telemetry/Sensor/BME680Sensor.cpp | 10 +--
 src/modules/Telemetry/Sensor/BME680Sensor.h   |  2 +-
 src/nimble/NimbleBluetooth.cpp                |  8 +-
 src/platform/esp32/WiFiOTA.cpp                |  8 +-
 src/platform/esp32/WiFiOTA.h                  |  2 +-
 16 files changed, 237 insertions(+), 176 deletions(-)

diff --git a/src/graphics/Screen.cpp b/src/graphics/Screen.cpp
index 474a000d5..be6d22a27 100644
--- a/src/graphics/Screen.cpp
+++ b/src/graphics/Screen.cpp
@@ -80,9 +80,6 @@ using graphics::numEmotes;
 
 using namespace meshtastic; /** @todo remove */
 
-String alertBannerMessage = "";
-uint32_t alertBannerUntil = 0;
-
 namespace graphics
 {
 
@@ -97,8 +94,12 @@ namespace graphics
 // A text message frame + debug frame + all the node infos
 FrameCallback *normalFrames;
 static uint32_t targetFramerate = IDLE_FRAMERATE;
-static String alertBannerMessage;
-static uint32_t alertBannerUntil = 0;
+// Global variables for alert banner - explicitly define with extern "C" linkage to prevent optimization
+extern "C" {
+static char alertBannerBuffer[256] = "";
+char *alertBannerMessage = alertBannerBuffer;
+uint32_t alertBannerUntil = 0;
+}
 
 uint32_t logo_timeout = 5000; // 4 seconds for EACH logo
 
@@ -146,10 +147,11 @@ extern bool hasUnreadMessage;
 // The banner appears in the center of the screen and disappears after the specified duration
 
 // Called to trigger a banner with custom message and duration
-void Screen::showOverlayBanner(const String &message, uint32_t durationMs)
+void Screen::showOverlayBanner(const char *message, uint32_t durationMs)
 {
     // Store the message and set the expiration timestamp
-    alertBannerMessage = message;
+    strncpy(alertBannerMessage, message, 255);
+    alertBannerMessage[255] = '\0'; // Ensure null termination
     alertBannerUntil = (durationMs == 0) ? 0 : millis() + durationMs;
 }
 
@@ -225,7 +227,8 @@ void Screen::drawDigitalClockFrame(OLEDDisplay *display, OLEDDisplayUiState *sta
     UIRenderer::drawBattery(display, x, y + 7, imgBattery, powerStatus);
 
     if (powerStatus->getHasBattery()) {
-        String batteryPercent = String(powerStatus->getBatteryChargePercent()) + "%";
+        char batteryPercent[8];
+        snprintf(batteryPercent, sizeof(batteryPercent), "%d%%", powerStatus->getBatteryChargePercent());
 
         display->setFont(FONT_SMALL);
 
@@ -255,16 +258,13 @@ void Screen::drawDigitalClockFrame(OLEDDisplay *display, OLEDDisplayUiState *sta
             hour = 12;
         }
 
-        // hours string
-        String hourString = String(hour);
+        // Format time string
+        char timeString[16];
+        snprintf(timeString, sizeof(timeString), "%d:%02d", hour, minute);
 
-        // minutes string
-        String minuteString = minute < 10 ? "0" + String(minute) : String(minute);
-
-        String timeString = hourString + ":" + minuteString;
-
-        // seconds string
-        String secondString = second < 10 ? "0" + String(second) : String(second);
+        // Format seconds string
+        char secondString[8];
+        snprintf(secondString, sizeof(secondString), "%02d", second);
 
         float scale = 1.5;
 
@@ -272,12 +272,12 @@ void Screen::drawDigitalClockFrame(OLEDDisplay *display, OLEDDisplayUiState *sta
         uint16_t segmentHeight = SEGMENT_HEIGHT * scale;
 
         // calculate hours:minutes string width
-        uint16_t timeStringWidth = timeString.length() * 5;
+        uint16_t timeStringWidth = strlen(timeString) * 5;
 
-        for (uint8_t i = 0; i < timeString.length(); i++) {
-            String character = String(timeString[i]);
+        for (uint8_t i = 0; i < strlen(timeString); i++) {
+            char character = timeString[i];
 
-            if (character == ":") {
+            if (character == ':') {
                 timeStringWidth += segmentHeight;
             } else {
                 timeStringWidth += segmentWidth + (segmentHeight * 2) + 4;
@@ -285,7 +285,7 @@ void Screen::drawDigitalClockFrame(OLEDDisplay *display, OLEDDisplayUiState *sta
         }
 
         // calculate seconds string width
-        uint16_t secondStringWidth = (secondString.length() * 12) + 4;
+        uint16_t secondStringWidth = (strlen(secondString) * 12) + 4;
 
         // sum these to get total string width
         uint16_t totalWidth = timeStringWidth + secondStringWidth;
@@ -297,15 +297,15 @@ void Screen::drawDigitalClockFrame(OLEDDisplay *display, OLEDDisplayUiState *sta
         uint16_t hourMinuteTextY = (display->getHeight() / 2) - (((segmentWidth * 2) + (segmentHeight * 3) + 8) / 2);
 
         // iterate over characters in hours:minutes string and draw segmented characters
-        for (uint8_t i = 0; i < timeString.length(); i++) {
-            String character = String(timeString[i]);
+        for (uint8_t i = 0; i < strlen(timeString); i++) {
+            char character = timeString[i];
 
-            if (character == ":") {
+            if (character == ':') {
                 drawSegmentedDisplayColon(display, hourMinuteTextX, hourMinuteTextY, scale);
 
                 hourMinuteTextX += segmentHeight + 6;
             } else {
-                drawSegmentedDisplayCharacter(display, hourMinuteTextX, hourMinuteTextY, character.toInt(), scale);
+                drawSegmentedDisplayCharacter(display, hourMinuteTextX, hourMinuteTextY, character - '0', scale);
 
                 hourMinuteTextX += segmentWidth + (segmentHeight * 2) + 4;
             }
@@ -457,7 +457,8 @@ void Screen::drawAnalogClockFrame(OLEDDisplay *display, OLEDDisplayUiState *stat
     UIRenderer::drawBattery(display, x, y + 7, imgBattery, powerStatus);
 
     if (powerStatus->getHasBattery()) {
-        String batteryPercent = String(powerStatus->getBatteryChargePercent()) + "%";
+        char batteryPercent[8];
+        snprintf(batteryPercent, sizeof(batteryPercent), "%d%%", powerStatus->getBatteryChargePercent());
 
         display->setFont(FONT_SMALL);
 
@@ -1711,21 +1712,30 @@ int Screen::handleTextMessage(const meshtastic_MeshPacket *packet)
             const char *longName = (node && node->has_user) ? node->user.long_name : nullptr;
 
             const char *msgRaw = reinterpret_cast<const char *>(packet->decoded.payload.bytes);
-            String msg = String(msgRaw);
-            msg.trim(); // Remove leading/trailing whitespace/newlines
 
-            String banner;
+            char banner[256];
 
-            // Match bell character or exact alert text
-            if (msg.indexOf("\x07") != -1) {
-                banner = "Alert Received";
-            } else {
-                banner = "New Message";
+            // Check for bell character in message to determine alert type
+            bool isAlert = false;
+            for (size_t i = 0; i < packet->decoded.payload.size && i < 100; i++) {
+                if (msgRaw[i] == '\x07') {
+                    isAlert = true;
+                    break;
+                }
             }
 
-            if (longName && longName[0]) {
-                banner += "\nfrom ";
-                banner += longName;
+            if (isAlert) {
+                if (longName && longName[0]) {
+                    snprintf(banner, sizeof(banner), "Alert Received\nfrom %s", longName);
+                } else {
+                    strcpy(banner, "Alert Received");
+                }
+            } else {
+                if (longName && longName[0]) {
+                    snprintf(banner, sizeof(banner), "New Message\nfrom %s", longName);
+                } else {
+                    strcpy(banner, "New Message");
+                }
             }
 
             screen->showOverlayBanner(banner, 3000);
diff --git a/src/graphics/Screen.h b/src/graphics/Screen.h
index 0d791e463..5f74f12aa 100644
--- a/src/graphics/Screen.h
+++ b/src/graphics/Screen.h
@@ -279,7 +279,7 @@ class Screen : public concurrency::OSThread
         enqueueCmd(cmd);
     }
 
-    void showOverlayBanner(const String &message, uint32_t durationMs = 3000);
+    void showOverlayBanner(const char *message, uint32_t durationMs = 3000);
 
     void startFirmwareUpdateScreen()
     {
@@ -698,8 +698,10 @@ class Screen : public concurrency::OSThread
 
 } // namespace graphics
 
-extern String alertBannerMessage;
+extern "C" {
+extern char *alertBannerMessage;
 extern uint32_t alertBannerUntil;
+}
 
 // Extern declarations for function symbols used in UIRenderer
 extern std::vector<std::string> functionSymbol;
diff --git a/src/graphics/draw/DebugRenderer.cpp b/src/graphics/draw/DebugRenderer.cpp
index 00aabedfb..54fba7618 100644
--- a/src/graphics/draw/DebugRenderer.cpp
+++ b/src/graphics/draw/DebugRenderer.cpp
@@ -181,19 +181,19 @@ void drawFrameWiFi(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t x, i
     }
 
     if (WiFi.status() != WL_CONNECTED) {
-        display->drawString(x, y, String("WiFi: Not Connected"));
+        display->drawString(x, y, "WiFi: Not Connected");
         if (config.display.heading_bold)
-            display->drawString(x + 1, y, String("WiFi: Not Connected"));
+            display->drawString(x + 1, y, "WiFi: Not Connected");
     } else {
-        display->drawString(x, y, String("WiFi: Connected"));
+        display->drawString(x, y, "WiFi: Connected");
         if (config.display.heading_bold)
-            display->drawString(x + 1, y, String("WiFi: Connected"));
+            display->drawString(x + 1, y, "WiFi: Connected");
 
-        display->drawString(x + SCREEN_WIDTH - display->getStringWidth("RSSI " + String(WiFi.RSSI())), y,
-                            "RSSI " + String(WiFi.RSSI()));
+        char rssiStr[32];
+        snprintf(rssiStr, sizeof(rssiStr), "RSSI %d", WiFi.RSSI());
+        display->drawString(x + SCREEN_WIDTH - display->getStringWidth(rssiStr), y, rssiStr);
         if (config.display.heading_bold) {
-            display->drawString(x + SCREEN_WIDTH - display->getStringWidth("RSSI " + String(WiFi.RSSI())) - 1, y,
-                                "RSSI " + String(WiFi.RSSI()));
+            display->drawString(x + SCREEN_WIDTH - display->getStringWidth(rssiStr) - 1, y, rssiStr);
         }
     }
 
@@ -212,7 +212,9 @@ void drawFrameWiFi(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t x, i
 
     */
     if (WiFi.status() == WL_CONNECTED) {
-        display->drawString(x, y + FONT_HEIGHT_SMALL * 1, "IP: " + String(WiFi.localIP().toString().c_str()));
+        char ipStr[64];
+        snprintf(ipStr, sizeof(ipStr), "IP: %s", WiFi.localIP().toString().c_str());
+        display->drawString(x, y + FONT_HEIGHT_SMALL * 1, ipStr);
     } else if (WiFi.status() == WL_NO_SSID_AVAIL) {
         display->drawString(x, y + FONT_HEIGHT_SMALL * 1, "SSID Not Found");
     } else if (WiFi.status() == WL_CONNECTION_LOST) {
@@ -231,11 +233,15 @@ void drawFrameWiFi(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t x, i
     }
 #else
     else {
-        display->drawString(x, y + FONT_HEIGHT_SMALL * 1, "Unkown status: " + String(WiFi.status()));
+        char statusStr[32];
+        snprintf(statusStr, sizeof(statusStr), "Unknown status: %d", WiFi.status());
+        display->drawString(x, y + FONT_HEIGHT_SMALL * 1, statusStr);
     }
 #endif
 
-    display->drawString(x, y + FONT_HEIGHT_SMALL * 2, "SSID: " + String(wifiName));
+    char ssidStr[64];
+    snprintf(ssidStr, sizeof(ssidStr), "SSID: %s", wifiName);
+    display->drawString(x, y + FONT_HEIGHT_SMALL * 2, ssidStr);
 
     display->drawString(x, y + FONT_HEIGHT_SMALL * 3, "http://meshtastic.local");
 
@@ -274,9 +280,9 @@ void drawFrameSettings(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t
             display->drawString(x + 1, y, batStr);
     } else {
         // Line 1
-        display->drawString(x, y, String("USB"));
+        display->drawString(x, y, "USB");
         if (config.display.heading_bold)
-            display->drawString(x + 1, y, String("USB"));
+            display->drawString(x + 1, y, "USB");
     }
 
     //    auto mode = DisplayFormatters::getModemPresetDisplayName(config.lora.modem_preset, true);
@@ -416,7 +422,7 @@ void drawLoRaFocused(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t x,
     display->setTextAlignment(TEXT_ALIGN_LEFT);
 
     // === First Row: Region / BLE Name ===
-    graphics::UIRenderer::drawNodes(display, x, compactFirstLine + 3, nodeStatus, 0, true);
+    graphics::UIRenderer::drawNodes(display, x, compactFirstLine + 3, nodeStatus, 0, true, "");
 
     uint8_t dmac[6];
     char shortnameble[35];
diff --git a/src/graphics/draw/NodeListRenderer.cpp b/src/graphics/draw/NodeListRenderer.cpp
index 4385e0f1b..bb7556f02 100644
--- a/src/graphics/draw/NodeListRenderer.cpp
+++ b/src/graphics/draw/NodeListRenderer.cpp
@@ -49,9 +49,9 @@ static int scrollIndex = 0;
 // Utility Functions
 // =============================
 
-String getSafeNodeName(meshtastic_NodeInfoLite *node)
+const char *getSafeNodeName(meshtastic_NodeInfoLite *node)
 {
-    String nodeName = "?";
+    static char nodeName[16] = "?";
     if (node->has_user && strlen(node->user.short_name) > 0) {
         bool valid = true;
         const char *name = node->user.short_name;
@@ -63,12 +63,13 @@ String getSafeNodeName(meshtastic_NodeInfoLite *node)
             }
         }
         if (valid) {
-            nodeName = name;
+            strncpy(nodeName, name, sizeof(nodeName) - 1);
+            nodeName[sizeof(nodeName) - 1] = '\0';
         } else {
-            char idStr[6];
-            snprintf(idStr, sizeof(idStr), "%04X", (uint16_t)(node->num & 0xFFFF));
-            nodeName = String(idStr);
+            snprintf(nodeName, sizeof(nodeName), "%04X", (uint16_t)(node->num & 0xFFFF));
         }
+    } else {
+        strcpy(nodeName, "?");
     }
     return nodeName;
 }
@@ -181,7 +182,7 @@ void drawEntryLastHeard(OLEDDisplay *display, meshtastic_NodeInfoLite *node, int
     bool isLeftCol = (x < SCREEN_WIDTH / 2);
     int timeOffset = (SCREEN_WIDTH > 128) ? (isLeftCol ? 7 : 10) : (isLeftCol ? 3 : 7);
 
-    String nodeName = getSafeNodeName(node);
+    const char *nodeName = getSafeNodeName(node);
 
     char timeStr[10];
     uint32_t seconds = sinceLastSeen(node);
@@ -224,7 +225,7 @@ void drawEntryHopSignal(OLEDDisplay *display, meshtastic_NodeInfoLite *node, int
 
     int barsXOffset = columnWidth - barsOffset;
 
-    String nodeName = getSafeNodeName(node);
+    const char *nodeName = getSafeNodeName(node);
 
     display->setTextAlignment(TEXT_ALIGN_LEFT);
     display->setFont(FONT_SMALL);
@@ -268,7 +269,7 @@ void drawNodeDistance(OLEDDisplay *display, meshtastic_NodeInfoLite *node, int16
     bool isLeftCol = (x < SCREEN_WIDTH / 2);
     int nameMaxWidth = columnWidth - (SCREEN_WIDTH > 128 ? (isLeftCol ? 25 : 28) : (isLeftCol ? 20 : 22));
 
-    String nodeName = getSafeNodeName(node);
+    const char *nodeName = getSafeNodeName(node);
     char distStr[10] = "";
 
     meshtastic_NodeInfoLite *ourNode = nodeDB->getMeshNode(nodeDB->getNodeNum());
@@ -363,7 +364,7 @@ void drawEntryCompass(OLEDDisplay *display, meshtastic_NodeInfoLite *node, int16
     // Adjust max text width depending on column and screen width
     int nameMaxWidth = columnWidth - (SCREEN_WIDTH > 128 ? (isLeftCol ? 25 : 28) : (isLeftCol ? 20 : 22));
 
-    String nodeName = getSafeNodeName(node);
+    const char *nodeName = getSafeNodeName(node);
 
     display->setTextAlignment(TEXT_ALIGN_LEFT);
     display->setFont(FONT_SMALL);
diff --git a/src/graphics/draw/NodeListRenderer.h b/src/graphics/draw/NodeListRenderer.h
index d35350cb8..aa92e34ea 100644
--- a/src/graphics/draw/NodeListRenderer.h
+++ b/src/graphics/draw/NodeListRenderer.h
@@ -59,7 +59,7 @@ void drawNodeInfo(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t x, in
 // Utility functions
 const char *getCurrentModeTitle(int screenWidth);
 void retrieveAndSortNodes(std::vector<NodeEntry> &nodeList);
-String getSafeNodeName(meshtastic_NodeInfoLite *node);
+const char *getSafeNodeName(meshtastic_NodeInfoLite *node);
 uint32_t sinceLastSeen(meshtastic_NodeInfoLite *node);
 void drawColumns(OLEDDisplay *display, int16_t x, int16_t y, const char **fields);
 
diff --git a/src/graphics/draw/NotificationRenderer.cpp b/src/graphics/draw/NotificationRenderer.cpp
index 6d8423adc..18c1c0d9f 100644
--- a/src/graphics/draw/NotificationRenderer.cpp
+++ b/src/graphics/draw/NotificationRenderer.cpp
@@ -2,6 +2,7 @@
 #include "DisplayFormatters.h"
 #include "NodeDB.h"
 #include "configuration.h"
+#include "graphics/Screen.h"
 #include "graphics/ScreenFonts.h"
 #include "graphics/SharedUIDisplay.h"
 #include "graphics/images.h"
@@ -17,8 +18,6 @@
 using namespace meshtastic;
 
 // External references to global variables from Screen.cpp
-extern String alertBannerMessage;
-extern uint32_t alertBannerUntil;
 extern std::vector<std::string> functionSymbol;
 extern std::string functionSymbolString;
 extern bool hasUnreadMessage;
@@ -77,7 +76,7 @@ void NotificationRenderer::drawWelcomeScreen(OLEDDisplay *display, OLEDDisplayUi
 void NotificationRenderer::drawAlertBannerOverlay(OLEDDisplay *display, OLEDDisplayUiState *state)
 {
     // Exit if no message is active or duration has passed
-    if (alertBannerMessage.length() == 0 || (alertBannerUntil != 0 && millis() > alertBannerUntil))
+    if (strlen(alertBannerMessage) == 0 || (alertBannerUntil != 0 && millis() > alertBannerUntil))
         return;
 
     // === Layout Configuration ===
@@ -85,28 +84,37 @@ void NotificationRenderer::drawAlertBannerOverlay(OLEDDisplay *display, OLEDDisp
     constexpr uint8_t lineSpacing = 1; // Extra space between lines
 
     // Search the message to determine if we need the bell added
-    bool needs_bell = (alertBannerMessage.indexOf("Alert Received") != -1);
+    bool needs_bell = (strstr(alertBannerMessage, "Alert Received") != nullptr);
 
     // Setup font and alignment
     display->setFont(FONT_SMALL);
     display->setTextAlignment(TEXT_ALIGN_LEFT); // We will manually center per line
 
     // === Split the message into lines (supports multi-line banners) ===
-    std::vector<String> lines;
-    int start = 0, newlineIdx;
-    while ((newlineIdx = alertBannerMessage.indexOf('\n', start)) != -1) {
-        lines.push_back(alertBannerMessage.substring(start, newlineIdx));
-        start = newlineIdx + 1;
+    const int MAX_LINES = 10;
+    char lines[MAX_LINES][256];
+    int lineCount = 0;
+
+    // Create a working copy of the message to tokenize
+    char messageCopy[256];
+    strncpy(messageCopy, alertBannerMessage, sizeof(messageCopy) - 1);
+    messageCopy[sizeof(messageCopy) - 1] = '\0';
+
+    char *line = strtok(messageCopy, "\n");
+    while (line != nullptr && lineCount < MAX_LINES) {
+        strncpy(lines[lineCount], line, sizeof(lines[lineCount]) - 1);
+        lines[lineCount][sizeof(lines[lineCount]) - 1] = '\0';
+        lineCount++;
+        line = strtok(nullptr, "\n");
     }
-    lines.push_back(alertBannerMessage.substring(start));
 
     // === Measure text dimensions ===
     uint16_t minWidth = (SCREEN_WIDTH > 128) ? 106 : 78;
     uint16_t maxWidth = 0;
-    std::vector<uint16_t> lineWidths;
-    for (const auto &line : lines) {
-        uint16_t w = display->getStringWidth(line.c_str(), line.length(), true);
-        lineWidths.push_back(w);
+    uint16_t lineWidths[MAX_LINES];
+    for (int i = 0; i < lineCount; i++) {
+        uint16_t w = display->getStringWidth(lines[i], strlen(lines[i]), true);
+        lineWidths[i] = w;
         if (w > maxWidth)
             maxWidth = w;
     }
@@ -115,7 +123,7 @@ void NotificationRenderer::drawAlertBannerOverlay(OLEDDisplay *display, OLEDDisp
     if (needs_bell && boxWidth < minWidth)
         boxWidth += (SCREEN_WIDTH > 128) ? 26 : 20;
 
-    uint16_t boxHeight = padding * 2 + lines.size() * FONT_HEIGHT_SMALL + (lines.size() - 1) * lineSpacing;
+    uint16_t boxHeight = padding * 2 + lineCount * FONT_HEIGHT_SMALL + (lineCount - 1) * lineSpacing;
 
     int16_t boxLeft = (display->width() / 2) - (boxWidth / 2);
     int16_t boxTop = (display->height() / 2) - (boxHeight / 2);
@@ -128,9 +136,9 @@ void NotificationRenderer::drawAlertBannerOverlay(OLEDDisplay *display, OLEDDisp
 
     // === Draw each line centered in the box ===
     int16_t lineY = boxTop + padding;
-    for (size_t i = 0; i < lines.size(); ++i) {
+    for (int i = 0; i < lineCount; i++) {
         int16_t textX = boxLeft + (boxWidth - lineWidths[i]) / 2;
-        uint16_t line_width = display->getStringWidth(lines[i].c_str(), lines[i].length(), true);
+        uint16_t line_width = display->getStringWidth(lines[i], strlen(lines[i]), true);
 
         if (needs_bell && i == 0) {
             int bellY = lineY + (FONT_HEIGHT_SMALL - 8) / 2;
diff --git a/src/graphics/draw/UIRenderer.cpp b/src/graphics/draw/UIRenderer.cpp
index f8524c1d1..becc5347d 100644
--- a/src/graphics/draw/UIRenderer.cpp
+++ b/src/graphics/draw/UIRenderer.cpp
@@ -15,6 +15,7 @@
 #include "target_specific.h"
 #include <OLEDDisplay.h>
 #include <RTC.h>
+#include <cstring>
 
 #if !MESHTASTIC_EXCLUDE_GPS
 
@@ -104,7 +105,7 @@ void drawGps(OLEDDisplay *display, int16_t x, int16_t y, const meshtastic::GPSSt
 // Draw status when GPS is disabled or not present
 void drawGpsPowerStatus(OLEDDisplay *display, int16_t x, int16_t y, const meshtastic::GPSStatus *gps)
 {
-    String displayLine;
+    const char *displayLine;
     int pos;
     if (y < FONT_HEIGHT_SMALL) { // Line 1: use short string
         displayLine = config.position.gps_mode == meshtastic_Config_PositionConfig_GpsMode_NOT_PRESENT ? "No GPS" : "GPS off";
@@ -119,7 +120,7 @@ void drawGpsPowerStatus(OLEDDisplay *display, int16_t x, int16_t y, const meshta
 
 void drawGpsAltitude(OLEDDisplay *display, int16_t x, int16_t y, const meshtastic::GPSStatus *gps)
 {
-    String displayLine = "";
+    char displayLine[32];
     if (!gps->getIsConnected() && !config.position.fixed_position) {
         // displayLine = "No GPS Module";
         // display->drawString(x + (SCREEN_WIDTH - (display->getStringWidth(displayLine))) / 2, y, displayLine);
@@ -128,9 +129,10 @@ void drawGpsAltitude(OLEDDisplay *display, int16_t x, int16_t y, const meshtasti
         // display->drawString(x + (SCREEN_WIDTH - (display->getStringWidth(displayLine))) / 2, y, displayLine);
     } else {
         geoCoord.updateCoords(int32_t(gps->getLatitude()), int32_t(gps->getLongitude()), int32_t(gps->getAltitude()));
-        displayLine = "Altitude: " + String(geoCoord.getAltitude()) + "m";
         if (config.display.units == meshtastic_Config_DisplayConfig_DisplayUnits_IMPERIAL)
-            displayLine = "Altitude: " + String(geoCoord.getAltitude() * METERS_TO_FEET) + "ft";
+            snprintf(displayLine, sizeof(displayLine), "Altitude: %.0fft", geoCoord.getAltitude() * METERS_TO_FEET);
+        else
+            snprintf(displayLine, sizeof(displayLine), "Altitude: %.0fm", geoCoord.getAltitude());
         display->drawString(x + (display->getWidth() - (display->getStringWidth(displayLine))) / 2, y, displayLine);
     }
 }
@@ -139,13 +141,13 @@ void drawGpsAltitude(OLEDDisplay *display, int16_t x, int16_t y, const meshtasti
 void drawGpsCoordinates(OLEDDisplay *display, int16_t x, int16_t y, const meshtastic::GPSStatus *gps)
 {
     auto gpsFormat = config.display.gps_format;
-    String displayLine = "";
+    char displayLine[32];
 
     if (!gps->getIsConnected() && !config.position.fixed_position) {
-        displayLine = "No GPS present";
+        strcpy(displayLine, "No GPS present");
         display->drawString(x + (display->getWidth() - (display->getStringWidth(displayLine))) / 2, y, displayLine);
     } else if (!gps->getHasLock() && !config.position.fixed_position) {
-        displayLine = "No GPS Lock";
+        strcpy(displayLine, "No GPS Lock");
         display->drawString(x + (display->getWidth() - (display->getStringWidth(displayLine))) / 2, y, displayLine);
     } else {
 
@@ -260,10 +262,10 @@ void drawNodes(OLEDDisplay *display, int16_t x, int16_t y, const meshtastic::Nod
 #endif
     display->drawString(x + 10, y - 2, usersString);
     int string_offset = (SCREEN_WIDTH > 128) ? 2 : 1;
-    if (additional_words != "") {
-        display->drawString(x + 10 + display->getStringWidth(usersString) + string_offset, y - 2, additional_words);
+    if (additional_words.length() > 0) {
+        display->drawString(x + 10 + display->getStringWidth(usersString) + string_offset, y - 2, additional_words.c_str());
         if (config.display.heading_bold)
-            display->drawString(x + 11 + display->getStringWidth(usersString) + string_offset, y - 2, additional_words);
+            display->drawString(x + 11 + display->getStringWidth(usersString) + string_offset, y - 2, additional_words.c_str());
     }
 }
 
@@ -616,7 +618,7 @@ void drawDeviceFocused(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t
 
 #if HAS_GPS
     if (config.position.gps_mode != meshtastic_Config_PositionConfig_GpsMode_ENABLED) {
-        String displayLine = "";
+        const char *displayLine;
         if (config.position.fixed_position) {
             displayLine = "Fixed GPS";
         } else {
@@ -644,8 +646,7 @@ void drawDeviceFocused(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t
     } else {
         display->drawString(
             x + SCREEN_WIDTH - display->getStringWidth("USB"),
-            ((rows == 4) ? compactSecondLine : ((SCREEN_HEIGHT > 64) ? compactSecondLine : moreCompactSecondLine)),
-            String("USB"));
+            ((rows == 4) ? compactSecondLine : ((SCREEN_HEIGHT > 64) ? compactSecondLine : moreCompactSecondLine)), "USB");
     }
 
     config.display.heading_bold = origBold;
@@ -975,9 +976,9 @@ void drawCompassAndLocationScreen(OLEDDisplay *display, OLEDDisplayUiState *stat
     bool origBold = config.display.heading_bold;
     config.display.heading_bold = false;
 
-    String Satelite_String = "Sat:";
+    const char *Satelite_String = "Sat:";
     display->drawString(0, ((SCREEN_HEIGHT > 64) ? compactFirstLine : moreCompactFirstLine), Satelite_String);
-    String displayLine = "";
+    const char *displayLine = ""; // Initialize to empty string by default
     if (config.position.gps_mode != meshtastic_Config_PositionConfig_GpsMode_ENABLED) {
         if (config.position.fixed_position) {
             displayLine = "Fixed GPS";
@@ -987,6 +988,7 @@ void drawCompassAndLocationScreen(OLEDDisplay *display, OLEDDisplayUiState *stat
         display->drawString(display->getStringWidth(Satelite_String) + 3,
                             ((SCREEN_HEIGHT > 64) ? compactFirstLine : moreCompactFirstLine), displayLine);
     } else {
+        displayLine = "GPS enabled"; // Set a value when GPS is enabled
         UIRenderer::drawGps(display, display->getStringWidth(Satelite_String) + 3,
                             ((SCREEN_HEIGHT > 64) ? compactFirstLine : moreCompactFirstLine) + 3, gpsStatus);
     }
@@ -1010,13 +1012,15 @@ void drawCompassAndLocationScreen(OLEDDisplay *display, OLEDDisplayUiState *stat
     }
 
     // If GPS is off, no need to display these parts
-    if (displayLine != "GPS off" && displayLine != "No GPS") {
+    if (strcmp(displayLine, "GPS off") != 0 && strcmp(displayLine, "No GPS") != 0) {
 
         // === Second Row: Altitude ===
-        String displayLine;
-        displayLine = " Alt: " + String(geoCoord.getAltitude()) + "m";
-        if (config.display.units == meshtastic_Config_DisplayConfig_DisplayUnits_IMPERIAL)
-            displayLine = " Alt: " + String(geoCoord.getAltitude() * METERS_TO_FEET) + "ft";
+        char displayLine[32];
+        if (config.display.units == meshtastic_Config_DisplayConfig_DisplayUnits_IMPERIAL) {
+            snprintf(displayLine, sizeof(displayLine), " Alt: %.0fft", geoCoord.getAltitude() * METERS_TO_FEET);
+        } else {
+            snprintf(displayLine, sizeof(displayLine), " Alt: %.0fm", geoCoord.getAltitude());
+        }
         display->drawString(x, ((SCREEN_HEIGHT > 64) ? compactSecondLine : moreCompactSecondLine), displayLine);
 
         // === Third Row: Latitude ===
diff --git a/src/modules/CannedMessageModule.cpp b/src/modules/CannedMessageModule.cpp
index 99813cba6..254e417f9 100644
--- a/src/modules/CannedMessageModule.cpp
+++ b/src/modules/CannedMessageModule.cpp
@@ -11,6 +11,7 @@
 #include "PowerFSM.h" // needed for button bypass
 #include "SPILock.h"
 #include "detect/ScanI2C.h"
+#include "graphics/Screen.h"
 #include "graphics/SharedUIDisplay.h"
 #include "graphics/images.h"
 #include "input/ScanAndSelect.h"
@@ -720,9 +721,7 @@ bool CannedMessageModule::handleSystemCommandInput(const InputEvent *event)
         return false;
 
     // Block ALL input if an alert banner is active
-    extern String alertBannerMessage;
-    extern uint32_t alertBannerUntil;
-    if (alertBannerMessage.length() > 0 && (alertBannerUntil == 0 || millis() <= alertBannerUntil)) {
+    if (strlen(alertBannerMessage) > 0 && (alertBannerUntil == 0 || millis() <= alertBannerUntil)) {
         return true;
     }
 
@@ -1381,28 +1380,32 @@ void CannedMessageModule::drawDestinationSelectionScreen(OLEDDisplay *display, O
         if (itemIndex >= totalEntries)
             break;
 
-        int xOffset = 0;
-        int yOffset = row * (FONT_HEIGHT_SMALL - 4) + rowYOffset;
-        String entryText;
+            int xOffset = 0;
+            int yOffset = row * (FONT_HEIGHT_SMALL - 4) + rowYOffset;
+            char entryText[64];
 
-        // Draw Channels First
-        if (itemIndex < numActiveChannels) {
-            uint8_t channelIndex = this->activeChannelIndices[itemIndex];
-            entryText = String("@") + String(channels.getName(channelIndex));
-        }
-        // Then Draw Nodes
-        else {
-            int nodeIndex = itemIndex - numActiveChannels;
-            if (nodeIndex >= 0 && nodeIndex < static_cast<int>(this->filteredNodes.size())) {
-                meshtastic_NodeInfoLite *node = this->filteredNodes[nodeIndex].node;
-                if (node) {
-                    entryText = node->is_favorite ? "* " + String(node->user.long_name) : String(node->user.long_name);
+            // Draw Channels First
+            if (itemIndex < numActiveChannels) {
+                uint8_t channelIndex = this->activeChannelIndices[itemIndex];
+                snprintf(entryText, sizeof(entryText), "@%s", channels.getName(channelIndex));
+            }
+            // Then Draw Nodes
+            else {
+                int nodeIndex = itemIndex - numActiveChannels;
+                if (nodeIndex >= 0 && nodeIndex < static_cast<int>(this->filteredNodes.size())) {
+                    meshtastic_NodeInfoLite *node = this->filteredNodes[nodeIndex].node;
+                    if (node) {
+                        if (node->is_favorite) {
+                            snprintf(entryText, sizeof(entryText), "* %s", node->user.long_name);
+                        } else {
+                            snprintf(entryText, sizeof(entryText), "%s", node->user.long_name);
+                        }
+                    }
                 }
             }
-        }
 
-        if (entryText.length() == 0 || entryText == "Unknown")
-            entryText = "?";
+            if (strlen(entryText) == 0 || strcmp(entryText, "Unknown") == 0)
+                strcpy(entryText, "?");
 
         // === Highlight background (if selected) ===
         if (itemIndex == destIndex) {
diff --git a/src/modules/SerialModule.cpp b/src/modules/SerialModule.cpp
index 8d280581c..f3921ef19 100644
--- a/src/modules/SerialModule.cpp
+++ b/src/modules/SerialModule.cpp
@@ -341,7 +341,7 @@ ProcessMessage SerialModuleRadio::handleReceived(const meshtastic_MeshPacket &mp
                 serialPrint->write(p.payload.bytes, p.payload.size);
             } else if (moduleConfig.serial.mode == meshtastic_ModuleConfig_SerialConfig_Serial_Mode_TEXTMSG) {
                 meshtastic_NodeInfoLite *node = nodeDB->getMeshNode(getFrom(&mp));
-                String sender = (node && node->has_user) ? node->user.short_name : "???";
+                const char *sender = (node && node->has_user) ? node->user.short_name : "???";
                 serialPrint->println();
                 serialPrint->printf("%s: %s", sender, p.payload.bytes);
                 serialPrint->println();
@@ -410,8 +410,8 @@ uint32_t SerialModule::getBaudRate()
 
 // Add this structure to help with parsing WindGust =       24.4 serial lines.
 struct ParsedLine {
-    String name;
-    String value;
+    char name[64];
+    char value[128];
 };
 
 /**
@@ -438,16 +438,30 @@ ParsedLine parseLine(const char *line)
     strncpy(nameBuf, line, nameLen);
     nameBuf[nameLen] = '\0';
 
-    // Create trimmed name string
-    String name = String(nameBuf);
-    name.trim();
+    // Trim whitespace from name
+    char *nameStart = nameBuf;
+    while (*nameStart && isspace(*nameStart))
+        nameStart++;
+    char *nameEnd = nameStart + strlen(nameStart) - 1;
+    while (nameEnd > nameStart && isspace(*nameEnd))
+        *nameEnd-- = '\0';
 
-    // Extract value after equals sign
-    String value = String(equals + 1);
-    value.trim();
+    // Copy trimmed name
+    strncpy(result.name, nameStart, sizeof(result.name) - 1);
+    result.name[sizeof(result.name) - 1] = '\0';
+
+    // Extract value part (after equals)
+    const char *valueStart = equals + 1;
+    while (*valueStart && isspace(*valueStart))
+        valueStart++;
+    strncpy(result.value, valueStart, sizeof(result.value) - 1);
+    result.value[sizeof(result.value) - 1] = '\0';
+
+    // Trim trailing whitespace from value
+    char *valueEnd = result.value + strlen(result.value) - 1;
+    while (valueEnd > result.value && isspace(*valueEnd))
+        *valueEnd-- = '\0';
 
-    result.name = name;
-    result.value = value;
     return result;
 }
 
@@ -517,16 +531,16 @@ void SerialModule::processWXSerial()
                         memcpy(line, &serialBytes[lineStart], lineEnd - lineStart);
 
                         ParsedLine parsed = parseLine(line);
-                        if (parsed.name.length() > 0) {
-                            if (parsed.name == "WindDir") {
-                                strlcpy(windDir, parsed.value.c_str(), sizeof(windDir));
+                        if (strlen(parsed.name) > 0) {
+                            if (strcmp(parsed.name, "WindDir") == 0) {
+                                strlcpy(windDir, parsed.value, sizeof(windDir));
                                 double radians = GeoCoord::toRadians(strtof(windDir, nullptr));
                                 dir_sum_sin += sin(radians);
                                 dir_sum_cos += cos(radians);
                                 dirCount++;
                                 gotwind = true;
-                            } else if (parsed.name == "WindSpeed") {
-                                strlcpy(windVel, parsed.value.c_str(), sizeof(windVel));
+                            } else if (strcmp(parsed.name, "WindSpeed") == 0) {
+                                strlcpy(windVel, parsed.value, sizeof(windVel));
                                 float newv = strtof(windVel, nullptr);
                                 velSum += newv;
                                 velCount++;
@@ -534,28 +548,28 @@ void SerialModule::processWXSerial()
                                     lull = newv;
                                 }
                                 gotwind = true;
-                            } else if (parsed.name == "WindGust") {
-                                strlcpy(windGust, parsed.value.c_str(), sizeof(windGust));
+                            } else if (strcmp(parsed.name, "WindGust") == 0) {
+                                strlcpy(windGust, parsed.value, sizeof(windGust));
                                 float newg = strtof(windGust, nullptr);
                                 if (newg > gust) {
                                     gust = newg;
                                 }
                                 gotwind = true;
-                            } else if (parsed.name == "BatVoltage") {
-                                strlcpy(batVoltage, parsed.value.c_str(), sizeof(batVoltage));
+                            } else if (strcmp(parsed.name, "BatVoltage") == 0) {
+                                strlcpy(batVoltage, parsed.value, sizeof(batVoltage));
                                 batVoltageF = strtof(batVoltage, nullptr);
                                 break; // last possible data we want so break
-                            } else if (parsed.name == "CapVoltage") {
-                                strlcpy(capVoltage, parsed.value.c_str(), sizeof(capVoltage));
+                            } else if (strcmp(parsed.name, "CapVoltage") == 0) {
+                                strlcpy(capVoltage, parsed.value, sizeof(capVoltage));
                                 capVoltageF = strtof(capVoltage, nullptr);
-                            } else if (parsed.name == "GXTS04Temp" || parsed.name == "Temperature") {
-                                strlcpy(temperature, parsed.value.c_str(), sizeof(temperature));
+                            } else if (strcmp(parsed.name, "GXTS04Temp") == 0 || strcmp(parsed.name, "Temperature") == 0) {
+                                strlcpy(temperature, parsed.value, sizeof(temperature));
                                 temperatureF = strtof(temperature, nullptr);
-                            } else if (parsed.name == "RainIntSum") {
-                                strlcpy(rainStr, parsed.value.c_str(), sizeof(rainStr));
+                            } else if (strcmp(parsed.name, "RainIntSum") == 0) {
+                                strlcpy(rainStr, parsed.value, sizeof(rainStr));
                                 rainSum = int(strtof(rainStr, nullptr));
-                            } else if (parsed.name == "Rain") {
-                                strlcpy(rainStr, parsed.value.c_str(), sizeof(rainStr));
+                            } else if (strcmp(parsed.name, "Rain") == 0) {
+                                strlcpy(rainStr, parsed.value, sizeof(rainStr));
                                 rain = strtof(rainStr, nullptr);
                             }
                         }
diff --git a/src/modules/Telemetry/HealthTelemetry.cpp b/src/modules/Telemetry/HealthTelemetry.cpp
index a2a18ba03..3a735b1fa 100644
--- a/src/modules/Telemetry/HealthTelemetry.cpp
+++ b/src/modules/Telemetry/HealthTelemetry.cpp
@@ -118,22 +118,31 @@ void HealthTelemetryModule::drawFrame(OLEDDisplay *display, OLEDDisplayUiState *
     }
 
     // Display "Health From: ..." on its own
-    display->drawString(x, y, "Health From: " + String(lastSender) + "(" + String(agoSecs) + "s)");
+    char headerStr[64];
+    snprintf(headerStr, sizeof(headerStr), "Health From: %s(%ds)", lastSender, (int)agoSecs);
+    display->drawString(x, y, headerStr);
 
-    String last_temp = String(lastMeasurement.variant.health_metrics.temperature, 0) + "°C";
+    char last_temp[16];
     if (moduleConfig.telemetry.environment_display_fahrenheit) {
-        last_temp = String(UnitConversions::CelsiusToFahrenheit(lastMeasurement.variant.health_metrics.temperature), 0) + "°F";
+        snprintf(last_temp, sizeof(last_temp), "%.0f°F",
+                 UnitConversions::CelsiusToFahrenheit(lastMeasurement.variant.health_metrics.temperature));
+    } else {
+        snprintf(last_temp, sizeof(last_temp), "%.0f°C", lastMeasurement.variant.health_metrics.temperature);
     }
 
     // Continue with the remaining details
-    display->drawString(x, y += _fontHeight(FONT_SMALL), "Temp: " + last_temp);
+    char tempStr[32];
+    snprintf(tempStr, sizeof(tempStr), "Temp: %s", last_temp);
+    display->drawString(x, y += _fontHeight(FONT_SMALL), tempStr);
     if (lastMeasurement.variant.health_metrics.has_heart_bpm) {
-        display->drawString(x, y += _fontHeight(FONT_SMALL),
-                            "Heart Rate: " + String(lastMeasurement.variant.health_metrics.heart_bpm, 0) + " bpm");
+        char heartStr[32];
+        snprintf(heartStr, sizeof(heartStr), "Heart Rate: %.0f bpm", lastMeasurement.variant.health_metrics.heart_bpm);
+        display->drawString(x, y += _fontHeight(FONT_SMALL), heartStr);
     }
     if (lastMeasurement.variant.health_metrics.has_spO2) {
-        display->drawString(x, y += _fontHeight(FONT_SMALL),
-                            "spO2: " + String(lastMeasurement.variant.health_metrics.spO2, 0) + " %");
+        char spo2Str[32];
+        snprintf(spo2Str, sizeof(spo2Str), "spO2: %.0f %%", lastMeasurement.variant.health_metrics.spO2);
+        display->drawString(x, y += _fontHeight(FONT_SMALL), spo2Str);
     }
 }
 
diff --git a/src/modules/Telemetry/PowerTelemetry.cpp b/src/modules/Telemetry/PowerTelemetry.cpp
index e42d718a5..e635b022d 100644
--- a/src/modules/Telemetry/PowerTelemetry.cpp
+++ b/src/modules/Telemetry/PowerTelemetry.cpp
@@ -152,14 +152,18 @@ void PowerTelemetryModule::drawFrame(OLEDDisplay *display, OLEDDisplayUiState *s
     }
 
     // Display "Pow. From: ..."
-    display->drawString(x, compactFirstLine, "Pow. From: " + String(lastSender) + " (" + String(agoSecs) + "s)");
+    char fromStr[64];
+    snprintf(fromStr, sizeof(fromStr), "Pow. From: %s (%ds)", lastSender, agoSecs);
+    display->drawString(x, compactFirstLine, fromStr);
 
     // Display current and voltage based on ...power_metrics.has_[channel/voltage/current]... flags
     const auto &m = lastMeasurement.variant.power_metrics;
     int lineY = compactSecondLine;
 
     auto drawLine = [&](const char *label, float voltage, float current) {
-        display->drawString(x, lineY, String(label) + ": " + String(voltage, 2) + "V " + String(current, 0) + "mA");
+        char lineStr[64];
+        snprintf(lineStr, sizeof(lineStr), "%s: %.2fV %.0fmA", label, voltage, current);
+        display->drawString(x, lineY, lineStr);
         lineY += _fontHeight(FONT_SMALL);
     };
 
diff --git a/src/modules/Telemetry/Sensor/BME680Sensor.cpp b/src/modules/Telemetry/Sensor/BME680Sensor.cpp
index 0e0212bc5..fce029deb 100644
--- a/src/modules/Telemetry/Sensor/BME680Sensor.cpp
+++ b/src/modules/Telemetry/Sensor/BME680Sensor.cpp
@@ -137,17 +137,17 @@ void BME680Sensor::updateState()
 #endif
 }
 
-void BME680Sensor::checkStatus(String functionName)
+void BME680Sensor::checkStatus(const char *functionName)
 {
     if (bme680.status < BSEC_OK)
-        LOG_ERROR("%s BSEC2 code: %s", functionName.c_str(), String(bme680.status).c_str());
+        LOG_ERROR("%s BSEC2 code: %d", functionName, bme680.status);
     else if (bme680.status > BSEC_OK)
-        LOG_WARN("%s BSEC2 code: %s", functionName.c_str(), String(bme680.status).c_str());
+        LOG_WARN("%s BSEC2 code: %d", functionName, bme680.status);
 
     if (bme680.sensor.status < BME68X_OK)
-        LOG_ERROR("%s BME68X code: %s", functionName.c_str(), String(bme680.sensor.status).c_str());
+        LOG_ERROR("%s BME68X code: %d", functionName, bme680.sensor.status);
     else if (bme680.sensor.status > BME68X_OK)
-        LOG_WARN("%s BME68X code: %s", functionName.c_str(), String(bme680.sensor.status).c_str());
+        LOG_WARN("%s BME68X code: %d", functionName, bme680.sensor.status);
 }
 
 #endif
diff --git a/src/modules/Telemetry/Sensor/BME680Sensor.h b/src/modules/Telemetry/Sensor/BME680Sensor.h
index 249c4b3e7..ce1fa4f3b 100644
--- a/src/modules/Telemetry/Sensor/BME680Sensor.h
+++ b/src/modules/Telemetry/Sensor/BME680Sensor.h
@@ -34,7 +34,7 @@ class BME680Sensor : public TelemetrySensor
                                 BSEC_OUTPUT_SENSOR_HEAT_COMPENSATED_HUMIDITY};
     void loadState();
     void updateState();
-    void checkStatus(String functionName);
+    void checkStatus(const char *functionName);
 
   public:
     BME680Sensor();
diff --git a/src/nimble/NimbleBluetooth.cpp b/src/nimble/NimbleBluetooth.cpp
index 80787092d..ef834db37 100644
--- a/src/nimble/NimbleBluetooth.cpp
+++ b/src/nimble/NimbleBluetooth.cpp
@@ -109,14 +109,14 @@ class NimbleBluetoothServerCallback : public NimBLEServerCallbacks
                 display->drawString(x_offset + x, y_offset + y, "Enter this code");
 
                 display->setFont(FONT_LARGE);
-                String displayPin(btPIN);
-                String pin = displayPin.substring(0, 3) + " " + displayPin.substring(3, 6);
+                char pin[8];
+                snprintf(pin, sizeof(pin), "%.3s %.3s", btPIN, btPIN + 3);
                 y_offset = display->height() == 64 ? y_offset + FONT_HEIGHT_SMALL - 5 : y_offset + FONT_HEIGHT_SMALL + 5;
                 display->drawString(x_offset + x, y_offset + y, pin);
 
                 display->setFont(FONT_SMALL);
-                String deviceName = "Name: ";
-                deviceName.concat(getDeviceName());
+                char deviceName[64];
+                snprintf(deviceName, sizeof(deviceName), "Name: %s", getDeviceName());
                 y_offset = display->height() == 64 ? y_offset + FONT_HEIGHT_LARGE - 6 : y_offset + FONT_HEIGHT_LARGE + 5;
                 display->drawString(x_offset + x, y_offset + y, deviceName);
             });
diff --git a/src/platform/esp32/WiFiOTA.cpp b/src/platform/esp32/WiFiOTA.cpp
index eac124dda..4cf157b4c 100644
--- a/src/platform/esp32/WiFiOTA.cpp
+++ b/src/platform/esp32/WiFiOTA.cpp
@@ -80,13 +80,13 @@ bool trySwitchToOTA()
     return true;
 }
 
-String getVersion()
+const char *getVersion()
 {
     const esp_partition_t *part = getAppPartition();
-    esp_app_desc_t app_desc;
+    static esp_app_desc_t app_desc;
     if (!getAppDesc(part, &app_desc))
-        return String();
-    return String(app_desc.version);
+        return "";
+    return app_desc.version;
 }
 
 } // namespace WiFiOTA
diff --git a/src/platform/esp32/WiFiOTA.h b/src/platform/esp32/WiFiOTA.h
index 61860ed5e..5a7ee348a 100644
--- a/src/platform/esp32/WiFiOTA.h
+++ b/src/platform/esp32/WiFiOTA.h
@@ -12,7 +12,7 @@ bool isUpdated();
 void recoverConfig(meshtastic_Config_NetworkConfig *network);
 void saveConfig(meshtastic_Config_NetworkConfig *network);
 bool trySwitchToOTA();
-String getVersion();
+const char *getVersion();
 } // namespace WiFiOTA
 
 #endif // WIFIOTA_H