Basic vanilla C boilerplate for STM32L100xC (Discovery L100C). Uses GCC. This was some class project without much practical use
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1.5 KiB

#include <common.h>
#include <gpio.h>
#include <systick.h>
#include <usart.h>
static void init_gpios(void)
{
gpio_enable(GPIOA);
gpio_enable(GPIOB);
gpio_enable(GPIOC);
gpio_set_mode(GPIOC, BIT8 | BIT9 | BIT7, MODER_OUTPUT);
gpio_set_mode(GPIOA, BIT8, MODER_OUTPUT);
}
static void init_clock(void)
{
// Flash timing - 64-bit access, pre-fetch, latency = 1
FLASH_ACR |= FLASH_ACR_ACC64; // Cannot write both at once
FLASH_ACR |= FLASH_ACR_PRFTEN | FLASH_ACR_LATENCY;
// Power on HSI (runs from MSI on start)
RCC_CR |= RCC_CR_HSION;
// Wait for HSIRDY
while (!(RCC_CR & RCC_CR_HSIRDY));
// Select HSI as the core clock source
RCC_CFGR &= ~RCC_CFGR_SW;
RCC_CFGR |= RCC_CFGR_SW_HSI;
}
static void init_usart(void)
{
gpio_set_af(GPIOC, BIT10 | BIT11, AF7);
// USART at C11, C12
RCC_APB1ENR |= RCC_APB1ENR_USART3EN;
// RATE 9600Bd 104.1875 (see datasheet for reference)8.6875
//USART3_BRR = 0x00683; // 9600
USART3_BRR = 0x0008A; // 115200
// USART enable
USART3_CR1 = USART_CR1_UE | USART_CR1_RE | USART_CR1_TE;
}
/** Called before main() */
void SystemInit(void)
{
init_clock();
systick_setup(16000);
init_gpios();
init_usart();
}
static uint32_t time = 0;
/** IRQ */
void SysTick_Handler(void)
{
time++;
if (time == 500) {
time = 0;
GPIOC_ODR ^= BIT9;
}
}
void delay(void)
{
for (int i = 0; i < 800000; i++) {
__asm__("nop");
}
}
int main(void)
{
while (1) {
delay();
GPIOC_ODR ^= BIT8;
usart_tx_string(USART3, "HELLO\r\n");
}
}