I2C Slave

main.c

#include "main.h"

#define I2C_DEVICE_NODE DT_NODELABEL(i2c1)
#define UART_DEVICE_NODE DT_NODELABEL(usart1)
#define LED0_NODE DT_ALIAS(led0)

static const struct device *const i2c_dev = DEVICE_DT_GET(I2C_DEVICE_NODE);
static const struct device *const uart_dev = DEVICE_DT_GET(UART_DEVICE_NODE);
static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED0_NODE, gpios);

char fifo_tx[128];
int txlen = 0;
char fifo_rx[128];

uint8_t i2c_rx[128];
uint8_t i2c_rxlen = 0;

void serial_cb(const struct device *dev, void *user_data)
{	
	if (uart_irq_tx_ready(uart_dev)) {
		if (--txlen > 0) {
			uart_fifo_fill(uart_dev, &fifo_tx[txlen], 1);
		} else {
			uart_irq_tx_disable(uart_dev);
		}
	}

	if (uart_irq_rx_ready(uart_dev)) {
		uart_fifo_read(uart_dev, fifo_rx, 1);
	}
}

void sertx(char *dat, int len) {
	for(len; len >= 0;) {
		fifo_tx[txlen++] = dat[len--];
	}

	uart_irq_tx_enable(uart_dev);	
}

int wrreq_cb(struct i2c_target_config *config){
	gpio_pin_set_dt(&led, 1);
	i2c_rxlen = 0;
	return 0;
}

int rdreq_cb(struct i2c_target_config *config, uint8_t *val){}

int wrrec_cb(struct i2c_target_config *config, uint8_t val){
	i2c_rx[i2c_rxlen++] = val;
	return 0;
}

int rdpro_cb(struct i2c_target_config *config){}

int stop_cb(struct i2c_target_config *config){
	sertx(i2c_rx, i2c_rxlen);
	gpio_pin_set_dt(&led, 0);
	return 0;
}

struct i2c_target_callbacks i2ccb = {
	wrreq_cb,
	rdreq_cb,
	wrrec_cb,
	rdpro_cb,
	stop_cb,
};

struct i2c_target_config i2ccfg;


void main(void) {
	i2ccfg.address = 0x29;
	i2ccfg.callbacks = &i2ccb;

	uart_irq_callback_user_data_set(uart_dev, serial_cb, NULL);
	uart_irq_rx_enable(uart_dev);

	i2c_target_register(i2c_dev, &i2ccfg);

	gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE);
	while (1) {
		k_sleep(K_MSEC(1));
	}
}