main.c

#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/i2c.h>
#include <libopencm3/stm32/syscfg.h>
#include <libopencm3/stm32/usart.h>

#include "printf.h"
#include "uart.h"
#include "bq76920.h"

#define PORT_LED GPIOA
#define PIN_LED1 GPIO5
#define PIN_LED2 GPIO7

void uart_out(char *data);
void hard_fault(void);
void delay(int t);
uint8_t check_faults(uint8_t *fault_counter);

static void clock_setup(void)
{
	rcc_clock_setup(&rcc_clock_config[RCC_CLOCK_CONFIG_HSI_16MHZ]);

	rcc_periph_clock_enable(RCC_GPIOA);
	rcc_periph_clock_enable(RCC_GPIOB);
	rcc_periph_clock_enable(RCC_SYSCFG);
	rcc_periph_clock_enable(RCC_USART1);
	rcc_periph_clock_enable(RCC_USART2);
	rcc_periph_clock_enable(RCC_I2C1);
}

static void i2c_setup(void)
{
	rcc_periph_reset_pulse(RST_I2C1);

	gpio_mode_setup(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO6 | GPIO7);
	gpio_set_af(GPIOB, GPIO_AF6, GPIO6 | GPIO7);
	gpio_set_output_options(GPIOB, GPIO_OTYPE_OD, GPIO_OSPEED_HIGH,
				GPIO6 | GPIO7);

	i2c_peripheral_disable(I2C1);
	i2c_disable_stretching(I2C1);
	i2c_enable_analog_filter(I2C1);
	i2c_set_digital_filter(I2C1, 5);
	i2c_set_speed(I2C1, i2c_speed_sm_100k, 16);
	i2c_set_7bit_addr_mode(I2C1);
	i2c_peripheral_enable(I2C1);
}

static void gpio_setup(void)
{
	gpio_mode_setup(PORT_LED, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE,
			PIN_LED1 | PIN_LED2);

	// Shutdown buttons
	gpio_mode_setup(GPIOA, GPIO_MODE_INPUT, GPIO_PUPD_PULLUP, GPIO0);

	// allert
	gpio_mode_setup(GPIOB, GPIO_MODE_INPUT, GPIO_PUPD_NONE, GPIO8);
}

void delay(int t)
{
	for (int i = 0; i < t; i++) {
		__asm__("nop");
	}
}

// Fast blink hard fault
void hard_fault(void)
{
	while (1) {
		gpio_toggle(PORT_LED, PIN_LED1);
		delay(1e6);
	};
}

uint8_t check_faults(uint8_t *fault_counter)
{
	uint8_t ret = 0;

	ret = bq76920_read_reg(SYS_STAT);
	if (ret) {
		gpio_set(PORT_LED, PIN_LED1);
		delay(1e6);
		if (*fault_counter < 10) {
			bq76920_clear_faults();
			bq76920_output_enable();
			(*fault_counter)++;
		} else {
			// Shutdown
			bq76920_shutdown();
		}
	}
	return ret;
}

int main(void)
{
	uint8_t ret = 0;
	char buf[128];
	uint8_t fault_counter = 0;

	clock_setup();
	gpio_setup();

	gpio_set(PORT_LED, PIN_LED1);
	delay(1e6);
	gpio_clear(PORT_LED, PIN_LED1);

	usart1_setup(115200);
	usart2_setup(9600);
	i2c_setup();

	sprintf(buf, "Starting BMS\r\n");
	uart1_out(buf);

	// Set CC_CFG to 0x19 as per the datasheet
	bq76920_write_reg(CC_CFG, 0x19);
	ret = bq76920_read_reg(CC_CFG);
	if (ret != 0x19) {
		// Something is wrong with the chip
		hard_fault();
	}

	bq76920_init();
	bq76920_clear_faults();
	bq76920_output_enable();

	struct cells c = {};

	while (1) {
		bq76920_read_cells_v(&c);
		uint8_t bal = bq76920_balance_cells(&c);
		sprintf(buf,
			"C0: %dmV C1: %dmV C2: %dmV C3: %dmV | Balance: %d\n\r",
			c.c0, c.c1, c.c2, c.c3, bal);
		uart1_out(buf);

		ret = check_faults(&fault_counter);
		if (ret) {
			if (ret & SYS_STAT_OCD) {
				sprintf(buf, "Fault: SYS_STAT_OCD\n\r");
				uart1_out(buf);
			}
			if (ret & SYS_STAT_SCD) {
				sprintf(buf, "Fault: SYS_STAT_SCD\n\r");
				uart1_out(buf);
			}
			if (ret & SYS_STAT_OV) {
				sprintf(buf, "Fault: SYS_STAT_OV\n\r");
				uart1_out(buf);
			}
			if (ret & SYS_STAT_UV) {
				sprintf(buf, "Fault: SYS_STAT_UV\n\r");
				uart1_out(buf);
			}
			if (ret & SYS_STAT_OVRD_ALERT) {
				sprintf(buf, "Fault: SYS_STAT_OVRD_ALERT\n\r");
				uart1_out(buf);
			}
			if (ret & SYS_STAT_DEVICE_XREADY) {
				sprintf(buf,
					"Fault: SYS_STAT_DEVICE_XREADY\n\r");
				uart1_out(buf);
			}
			sprintf(buf, "Fault Counter: %d\n\r", fault_counter);
			uart1_out(buf);
		}

		if (!gpio_get(GPIOA, GPIO0) || uart_get_shutdown()) {
			sprintf(buf, "Shutting down\n\r");
			uart1_out(buf);
			bq76920_shutdown();
		}
		gpio_toggle(PORT_LED, PIN_LED2);
		delay(5e6);
	}

	return 0;
}