firmware/src/plugins/SerialPlugin.cpp

#include "SerialPlugin.h"
#include "MeshService.h"
#include "NodeDB.h"
#include "RTC.h"
#include "Router.h"
#include "configuration.h"
#include <Arduino.h>

#include <assert.h>

/*
    SerialPlugin
        An overly simplistic interface to send messages over the mesh network by sending strings
        over a serial port.

        Default is to use RX GPIO 16 and TX GPIO 17.

    Need help with this plugin? Post your question on the Meshtastic Discourse:
       https://meshtastic.discourse.group

    Basic Usage:

        1) Enable the plugin by setting SERIALPLUGIN_ENABLED to 1.
        2) Set the pins (RXD2 / TXD2) for your preferred RX and TX GPIO pins.
           On tbeam, recommend to use:
                #define RXD2 35
                #define TXD2 15
        3) Set SERIALPLUGIN_TIMEOUT to the amount of time to wait before we consider
           your packet as "done".
        4) (Optional) In SerialPlugin.h set the port to PortNum_TEXT_MESSAGE_APP if you want to
           send messages to/from the general text message channel.
        5) Connect to your device over the serial interface at 38400 8N1.
        6) Send a packet up to 240 bytes in length. This will get relayed over the mesh network.
        7) (Optional) Set SERIALPLUGIN_ECHO to 1 and any message you send out will be echoed back
           to your device.

    TODO (in this order):
        * Once protobufs regenerated with the new port, update SerialPlugin.h
        * Ensure this works on a tbeam
        * Define a verbose RX mode to report on mesh and packet infomration.
            - This won't happen any time soon.

    KNOWN PROBLEMS
        * Until the plugin is initilized by the startup sequence, the TX pin is in a floating
          state. Device connected to that pin may see this as "noise".
        * Will not work on NRF and the Linux device targets.


*/

#define RXD2 16
#define TXD2 17
#define SERIALPLUGIN_RX_BUFFER 128
#define SERIALPLUGIN_STRING_MAX Constants_DATA_PAYLOAD_LEN
#define SERIALPLUGIN_TIMEOUT 250
#define SERIALPLUGIN_BAUD 38400
#define SERIALPLUGIN_ACK 1

SerialPlugin *serialPlugin;
SerialPluginRadio *serialPluginRadio;

SerialPlugin::SerialPlugin() : concurrency::OSThread("SerialPlugin") {}

char serialStringChar[Constants_DATA_PAYLOAD_LEN];

int32_t SerialPlugin::runOnce()
{
#ifndef NO_ESP32

    /*
        Uncomment the preferences below if you want to use the plugin
        without having to configure it from the PythonAPI or WebUI.
    */

    // radioConfig.preferences.serialplugin_enabled = 1;
    // radioConfig.preferences.serialplugin_rxd = 35;
    // radioConfig.preferences.serialplugin_txd = 15;
    // radioConfig.preferences.serialplugin_timeout = 1000;

    if (radioConfig.preferences.serialplugin_enabled) {

        if (firstTime) {

            // Interface with the serial peripheral from in here.
            DEBUG_MSG("Initilizing serial peripheral interface\n");

            if (radioConfig.preferences.serialplugin_rxd && radioConfig.preferences.serialplugin_txd) {
                Serial2.begin(SERIALPLUGIN_BAUD, SERIAL_8N1, radioConfig.preferences.serialplugin_rxd,
                              radioConfig.preferences.serialplugin_txd);

            } else {
                Serial2.begin(SERIALPLUGIN_BAUD, SERIAL_8N1, RXD2, TXD2);
            }

            if (radioConfig.preferences.serialplugin_timeout) {
                Serial2.setTimeout(
                    radioConfig.preferences.serialplugin_timeout); // Number of MS to wait to set the timeout for the string.

            } else {
                Serial2.setTimeout(SERIALPLUGIN_TIMEOUT); // Number of MS to wait to set the timeout for the string.
            }

            Serial2.setRxBufferSize(SERIALPLUGIN_RX_BUFFER);

            serialPluginRadio = new SerialPluginRadio();

            firstTime = 0;

        } else {
            String serialString;

            while (Serial2.available()) {
                serialString = Serial2.readString();
                serialString.toCharArray(serialStringChar, Constants_DATA_PAYLOAD_LEN);

                serialPluginRadio->sendPayload();

                DEBUG_MSG("Received: %s\n", serialStringChar);
            }
        }

        return (10);
    } else {
        DEBUG_MSG("Serial Plugin Disabled\n");

        return (INT32_MAX);
    }

#endif
}

MeshPacket *SerialPluginRadio::allocReply()
{

    auto reply = allocDataPacket(); // Allocate a packet for sending

    return reply;
}

void SerialPluginRadio::sendPayload(NodeNum dest, bool wantReplies)
{
    MeshPacket *p = allocReply();
    p->to = dest;
    p->decoded.want_response = wantReplies;

    p->want_ack = SERIALPLUGIN_ACK;

    p->decoded.data.payload.size = strlen(serialStringChar); // You must specify how many bytes are in the reply
    memcpy(p->decoded.data.payload.bytes, serialStringChar, p->decoded.data.payload.size);

    service.sendToMesh(p);
}

bool SerialPluginRadio::handleReceived(const MeshPacket &mp)
{
#ifndef NO_ESP32

    if (radioConfig.preferences.serialplugin_enabled) {

        auto &p = mp.decoded.data;
        // DEBUG_MSG("Received text msg self=0x%0x, from=0x%0x, to=0x%0x, id=%d, msg=%.*s\n",
        //          nodeDB.getNodeNum(), mp.from, mp.to, mp.id, p.payload.size, p.payload.bytes);

        if (mp.from == nodeDB.getNodeNum()) {

            /*
             * If radioConfig.preferences.serialplugin_echo is true, then echo the packets that are sent out back to the TX
             * of the serial interface.
             */
            if (radioConfig.preferences.serialplugin_echo) {

                // For some reason, we get the packet back twice when we send out of the radio.
                //   TODO: need to find out why.
                if (lastRxID != mp.id) {
                    lastRxID = mp.id;
                    // DEBUG_MSG("* * Message came this device\n");
                    // Serial2.println("* * Message came this device");
                    Serial2.printf("%s", p.payload.bytes);
                }
            }

        } else {
            // DEBUG_MSG("* * Message came from the mesh\n");
            // Serial2.println("* * Message came from the mesh");
            Serial2.printf("%s", p.payload.bytes);
        }

    } else {
        DEBUG_MSG("Serial Plugin Disabled\n");
    }

#endif

    return true; // Let others look at this message also if they want
}