TCA8418: Interrupt based notify of new key events

src/input/TCA8418KeyboardBase.cpp

@@ -43,6 +43,18 @@ void TCA8418KeyboardBase::begin(uint8_t addr, TwoWire *wire)
     m_wire = wire;
     m_wire->begin();
     reset();
+
+#ifdef KB_INT
+    interruptInstance = this;
+    auto interruptHandler = []() {
+        interruptInstance->notifyObservers(interruptInstance);
+    };
+
+    ::pinMode(KB_INT, INPUT_PULLUP);
+    attachInterrupt(KB_INT, interruptHandler, FALLING);
+
+    enableInterrupts();
+#endif
 }
 
 void TCA8418KeyboardBase::begin(i2c_com_fptr_t r, i2c_com_fptr_t w, uint8_t addr)
@@ -157,6 +169,11 @@ void TCA8418KeyboardBase::trigger()
             released(key);
         }
     }
+
+#ifdef KB_INT
+    // Reset interrupt mask so we can receive future interrupts
+    writeRegister(TCA8418_REG_INT_STAT, 3);
+#endif
 }
 
 void TCA8418KeyboardBase::pressed(uint8_t key)
@@ -292,6 +309,8 @@ void TCA8418KeyboardBase::disableInterrupts()
     writeRegister(TCA8418_REG_CFG, value);
 };
 
+TCA8418KeyboardBase* TCA8418KeyboardBase::interruptInstance;
+
 void TCA8418KeyboardBase::enableMatrixOverflow()
 {
     uint8_t value = readRegister(TCA8418_REG_CFG);

src/input/TCA8418KeyboardBase.h

@@ -1,6 +1,7 @@
 // Based on the MPR121 Keyboard and Adafruit TCA8418 library
 #include "configuration.h"
 #include <Wire.h>
+#include "kbInterrupt.h"
 
 /**
  * @brief TCA8418KeyboardBase is the base class for TCA8418 keyboard handling.
@@ -8,7 +9,7 @@
  * and handling key states. It is designed to be extended for specific keyboard implementations.
  * It supports both I2C communication and function pointers for custom I2C operations.
  */
-class TCA8418KeyboardBase
+class TCA8418KeyboardBase : public KbInterruptObservable
 {
   public:
     enum TCA8418Key : uint8_t {
@@ -142,6 +143,7 @@ class TCA8418KeyboardBase
     // enable / disable interrupts for matrix and GPI pins
     void enableInterrupts();
     void disableInterrupts();
+    static TCA8418KeyboardBase* interruptInstance;
 
     // ignore key events when FIFO buffer is full or not.
     void enableMatrixOverflow();

src/input/kbI2cBase.cpp

@@ -46,6 +46,7 @@ uint8_t read_from_14004(TwoWire *i2cBus, uint8_t reg, uint8_t *data, uint8_t len
 
 int32_t KbI2cBase::runOnce()
 {
+    int32_t interval = 300;
     if (!i2cBus) {
         switch (cardkb_found.port) {
         case ScanI2C::WIRE1:
@@ -61,6 +62,7 @@ int32_t KbI2cBase::runOnce()
             }
             if (cardkb_found.address == TCA8418_KB_ADDR) {
                 TCAKeyboard.begin(TCA8418_KB_ADDR, &Wire1);
+                observe(&TCAKeyboard);
             }
             break;
 #endif
@@ -76,6 +78,7 @@ int32_t KbI2cBase::runOnce()
             }
             if (cardkb_found.address == TCA8418_KB_ADDR) {
                 TCAKeyboard.begin(TCA8418_KB_ADDR, &Wire);
+                observe(&TCAKeyboard);
             }
             break;
         case ScanI2C::NO_I2C:
@@ -249,6 +252,7 @@ int32_t KbI2cBase::runOnce()
         break;
     }
     case 0x84: { // Adafruit TCA8418
+        interval = 3000;  // Less polling, we have interrupts with onNotify()
         TCAKeyboard.trigger();
         InputEvent e;
         while (TCAKeyboard.hasEvent()) {
@@ -331,7 +335,6 @@ int32_t KbI2cBase::runOnce()
                 LOG_DEBUG("TCA8418 Notifying: %i Char: %c", e.inputEvent, e.kbchar);
                 this->notifyObservers(&e);
             }
-            TCAKeyboard.trigger();
         }
         break;
     }
@@ -518,5 +521,17 @@ int32_t KbI2cBase::runOnce()
     default:
         LOG_WARN("Unknown kb_model 0x%02x", kb_model);
     }
-    return 300;
+
+    // If new interrupt triggered while we were processing the previous, reinvoke with 0 interval right away
+    if (pendingInterruptCount) pendingInterruptCount--;
+    if (pendingInterruptCount) return 0;
+
+    return interval;
+}
+
+int KbI2cBase::onNotify(KbInterruptObservable* src)
+{
+    pendingInterruptCount++;
+    setInterval(0);
+    return 0;
 }

src/input/kbI2cBase.h

@@ -5,16 +5,18 @@
 #include "MPR121Keyboard.h"
 #include "Wire.h"
 #include "concurrency/OSThread.h"
+#include "kbInterrupt.h"
 
 class TCA8418KeyboardBase;
 
-class KbI2cBase : public Observable<const InputEvent *>, public concurrency::OSThread
+class KbI2cBase : public Observable<const InputEvent *>, public KbInterruptObserver, public concurrency::OSThread
 {
   public:
     explicit KbI2cBase(const char *name);
 
   protected:
     virtual int32_t runOnce() override;
+    virtual int onNotify(KbInterruptObservable* src) override;
 
   private:
     const char *_originName;
@@ -24,5 +26,6 @@ class KbI2cBase : public Observable<const InputEvent *>, public concurrency::OST
     BBQ10Keyboard Q10keyboard;
     MPR121Keyboard MPRkeyboard;
     TCA8418KeyboardBase &TCAKeyboard;
+    volatile uint8_t pendingInterruptCount = 0;
     bool is_sym = false;
 };

src/input/kbInterrupt.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include "Observer.h"
+
+class KbInterruptObservable : public Observable<KbInterruptObservable*>
+{
+};
+
+class KbInterruptObserver : public Observer<KbInterruptObservable*>
+{
+};