STM8L152C6 ADC minimal

// Source code under CC0 1.0
#include <stdint.h>
#include <stdio.h>

#define EVER (;;)

//ADC Registers
#define ADC1_CR1        (*(volatile uint8_t *)0x5340)
#define ADC1_CR2        (*(volatile uint8_t *)0x5341)
#define ADC1_CR3        (*(volatile uint8_t *)0x5342)

//System Configuration
#define SYSCFG_RMPCR1   (*(volatile uint8_t *)0x509E)
#define USART1TR_REMAP1 (1 << 5)
#define USART1TR_REMAP0 (1 << 4)

//Clock
#define CLK_DIVR        (*(volatile uint8_t *)0x50C0)
#define CLK_PCKENR1     (*(volatile uint8_t *)0x50C3)
#define CLK_PCKENR2     (*(volatile uint8_t *)0x50C4)

//USART
#define USART1_SR       (*(volatile uint8_t *)0x5230)
#define USART1_DR       (*(volatile uint8_t *)0x5231)
#define USART1_BRR1     (*(volatile uint8_t *)0x5232)
#define USART1_BRR2     (*(volatile uint8_t *)0x5233)
#define USART1_CR2      (*(volatile uint8_t *)0x5235)
#define USART1_CR3      (*(volatile uint8_t *)0x5236)

#define USART_CR2_TEN   (1 << 3)
#define USART_CR3_STOP2 (1 << 5)
#define USART_CR3_STOP1 (1 << 4)
#define USART_SR_TXE    (1 << 7)

// we need to provide putchar, as it is controller specific
void putchar(char c)
{
    while(!(USART1_SR & USART_SR_TXE));

    USART1_DR = c;
}

void uart_init(void)
{
    // Remap USART1 TX to PA2 and RX to PA4
    SYSCFG_RMPCR1 |= USART1TR_REMAP0;
    SYSCFG_RMPCR1 &= ~USART1TR_REMAP1;

    USART1_CR2 = USART_CR2_TEN; // Allow TX and RX
    USART1_CR3 &= ~(USART_CR3_STOP1 | USART_CR3_STOP2); // 1 stop bit
    USART1_BRR2 = 0x03; USART1_BRR1 = 0x68; // 9600 baud
}

void main(void)
{
    unsigned long i = 0;

    CLK_DIVR = 0x00; // Set the frequency to 16 MHz
    CLK_PCKENR1 |= 0xFF; //(1 << 5) & (1 << 7); // Enable peripherals UART & ADC

    uart_init();

    printf("Restarted...\r\n");

    for EVER
    {
        ADC1_CR1 = 0x01;
        printf("ADC_CR1: %X\r\n", ADC1_CR1);
        for(i = 0; i < 0xFFFFF; i++); // Sleep
    }
}