STM32

STM32F103 Since I tried to get the IDE working with version 2.0+ working with linux, I had a problem. So I wanted it to work, so I started with bare metal:

/**

******************************************************************************

* @file : main.c

* @author : Sherm and STM32CubeIDE

* @brief : Main program body

******************************************************************************

* Testing fastest loop speed. found 4MHz with 8MHz crystal.. but good

******************************************************************************

#include <stdint.h>

#if !defined(__SOFT_FP__) && defined(__ARM_FP)

#warning "FPU is not initialized, but the project is compiling for an FPU. Please initialize the FPU before use."

#endif

#define RCC_BASE 0x40021000

#define RCC_CR (*((volatile unsigned int *)(RCC_BASE + 0x00)))

#define RCC_CFGR (*((volatile unsigned int *)(RCC_BASE + 0x04)))

#define FLASH_ACR (*((volatile unsigned int *)(0x40022000)))

#define GPIOC_BSRR (*((volatile unsigned int *)0x40011010))

void SetClock72MHz(void) {

// 1. Enable HSE (External Crystal)

RCC_CR |= (1 << 16);

while (!(RCC_CR & (1 << 17))); // Wait until HSE is ready

// 2. Set Flash Latency (IMPORTANT: 72MHz requires 2 wait states)

FLASH_ACR |= 0x2;

// 3. Configure PLL: HSE as source, Multiply by 9 (8MHz * 9 = 72MHz)

// PLLSRC (bit 16) = 1, PLLMUL (bits 18-21) = 0111 (7) for x9

RCC_CFGR &= ~((0xF << 18) | (1 << 16)); // Clear

RCC_CFGR |= ((0x7 << 18) | (1 << 16));

// 4. Enable PLL

RCC_CR |= (1 << 24);

while (!(RCC_CR & (1 << 25))); // Wait until PLL is locked

// 5. Select PLL as System Clock

RCC_CFGR &= ~(0x3); // Clear SW bits

RCC_CFGR |= 0x2; // Set SW to PLL

while (((RCC_CFGR >> 2) & 0x3) != 0x2); // Wait for switch

}

int main(void) {

SetClock72MHz(); // Now running at 72MHz

// Enable GPIOC clock

*((volatile unsigned int *)0x40021018) |= (1 << 4);

// Set PC13 to 50MHz Output (0x3)

*((volatile unsigned int *)0x40011004) &= ~(0xF << 20);

*((volatile unsigned int *)0x40011004) |= (0x3 << 20);

/* while(1) {

// Direct toggle (Fastest possible)

*((volatile unsigned int *)0x4001100C) ^= (1 << 13);

}*/

while(1) {

GPIOC_BSRR = (1 << 13); // Set High

GPIOC_BSRR = (1 << (13 + 16)); // Reset Low

GPIOC_BSRR = (1 << 13);