uint8_t *txbuf;
uint8_t *rxbuf;

bool btn1;
bool btn2;
bool btn3;
bool btn4;
bool btn5;
bool btn6;
bool btn7;
bool btn8;

// SETUP
// ------------------

void setup() {

  static uint8_t _txbuf[8] __attribute__((section(".sram2")));
  static uint8_t _rxbuf[8] __attribute__((section(".sram2")));

  txbuf = _txbuf;
  rxbuf = _rxbuf;
}

// LOOP
// ------------------

void loop() {
  chThdSleepMilliseconds(1);

  txbuf[0] = 0x42;
  txbuf[1] = 0;
  txbuf[2] = 0;
  txbuf[3] = 0;
  txbuf[4] = 0;
  txbuf[5] = 0;
  txbuf[6] = 0;
  txbuf[7] = 0;

  spiSelect(&SPID1);
  spiSend(&SPID1, 1, &txbuf[0]);
  palSetPadMode(GPIOA, 7, PAL_MODE_INPUT); // MOSI -> tristate
  spiReceive(&SPID1, 4, &rxbuf[0]);
  spiUnselect(&SPID1);
  palSetPadMode(GPIOA, 7, PAL_MODE_ALTERNATE(5)); // MOSI -> output

  btn1 = rxbuf[0] & 0x01 ? true : false;
  btn2 = rxbuf[1] & 0x01 ? true : false;
  btn3 = rxbuf[2] & 0x01 ? true : false;
  btn4 = rxbuf[3] & 0x01 ? true : false;
  btn5 = rxbuf[0] & 0x10 ? true : false;
  btn6 = rxbuf[1] & 0x10 ? true : false;
  btn7 = rxbuf[2] & 0x10 ? true : false;
  btn8 = rxbuf[3] & 0x10 ? true : false;
}

// ------------------------------------------------------------------------------------------------
// THREADS
// ------------------------------------------------------------------------------------------------

msg_t ThreadX2() {
  setup();
  while (!chThdShouldTerminate()) {
    loop();
    chThdSleepMilliseconds(1);
  }

  chThdExit((msg_t)0);
}

static msg_t ThreadX(void *arg) { ((attr_parent *)arg)->ThreadX2(); }

WORKING_AREA(waThreadX, 1024);

Thread *Thd;

Thd = chThdCreateStatic(waThreadX, sizeof(waThreadX), NORMALPRIO, ThreadX,
                        (void *)this);

btn1 = false;
btn2 = false;
btn3 = false;
btn4 = false;
btn5 = false;
btn6 = false;
btn7 = false;
btn8 = false;

outlet_button1 = btn1;
outlet_button2 = btn2;
outlet_button3 = btn3;
outlet_button4 = btn4;
outlet_button5 = btn5;
outlet_button6 = btn6;
outlet_button7 = btn7;
outlet_button8 = btn8;

chThdTerminate(Thd);
chThdWait(Thd);