#include <SPI.h>
// Wiring:
// Master RX GP16 <-> GP19 Slave TX
// Master CS GP17 <-> GP17 Slave CS
// Master CK GP18 <-> GP18 Slave CK
// Master TX GP19 <-> GP16 Slave RX
SPISettings spisettings(1000000, MSBFIRST, SPI_MODE0);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  while (!Serial) {
    delay(10);
  }
  Serial.println("Hello, Raspberry Pi Pico!");

  SPI.setRX(16);
  SPI.setCS(17);
  SPI.setSCK(18);
  SPI.setTX(19);
  SPI.begin(true);
  delay(5000);
}

int transmits = 0;

void loop() {
  char msg[42];
  memset(msg, 0, sizeof(msg));
  sprintf(msg, "What's up? This is transmission %d", transmits);
  Serial.printf("\n\nM-SEND: '%s'\n", msg);
  SPI.beginTransaction(spisettings);
  SPI.transfer(msg, sizeof(msg));
  SPI.endTransaction();
  Serial.printf("M-RECV: '%s'\n", msg);
  transmits++;
  delay(5000);
}