1. Hold KEYPAD_RST low for at least 120 us, release it high, and wait at least 120 us.
2. Initialize I2C on I2C_SDA/I2C_SCL.
3. Verify the TCA8418 responds, then configure ROW0–ROW4 and COL0–COL3 for keypad scanning.
4. Configure the keypad debounce and event/interrupt registers.
5. Configure GPIO10 for falling-edge or low-level interrupt handling.
6. Initialize ADC_POT1/ADC_POT2 and LATCH1/LATCH2.

• U2 performs matrix scanning and debounce; ESP32 firmware must not directly scan ROW1..ROW5 or COL1..COL4.
• KEYPAD_INT is active-low open-drain.
• On interrupt, read the keypad event count/FIFO, process all queued press/release events, clear the interrupt condition according to the TCA8418 register procedure, and repeat if more events remain.
• Maintain a 5×4 logical key map from TCA8418 row/column event codes to Stream Deck actions.

Cpp
#include <Wire.h>

constexpr int PIN_SDA = 8;
constexpr int PIN_SCL = 9;
constexpr int PIN_INT = 10;
constexpr int PIN_RST = 11;
constexpr int PIN_POT1 = 1;
constexpr int PIN_POT2 = 2;
constexpr int PIN_LATCH1 = 13;
constexpr int PIN_LATCH2 = 14;

volatile bool keypadPending = false;
void IRAM_ATTR keypadISR() { keypadPending = true; }

void setup() {
  pinMode(PIN_RST, OUTPUT);
  digitalWrite(PIN_RST, LOW);
  delayMicroseconds(120);
  digitalWrite(PIN_RST, HIGH);
  delayMicroseconds(120);

  Wire.begin(PIN_SDA, PIN_SCL);
  pinMode(PIN_INT, INPUT);       // external pull-up fitted
  pinMode(PIN_LATCH1, INPUT);    // external pull-up fitted
  pinMode(PIN_LATCH2, INPUT);    // external pull-up fitted
  attachInterrupt(PIN_INT, keypadISR, FALLING);
  analogReadResolution(12);

  // Configure TCA8418 keypad rows/columns, debounce, FIFO and interrupt registers here.
}

void loop() {
  if (keypadPending) {
    keypadPending = false;
    // Drain TCA8418 key-event FIFO and clear its interrupt status.
  }
  int pot1 = analogRead(PIN_POT1);
  int pot2 = analogRead(PIN_POT2);
  bool latch1Closed = digitalRead(PIN_LATCH1) == LOW;
  bool latch2Closed = digitalRead(PIN_LATCH2) == LOW;
}