#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <stm32c0xx.h>

// 1. 极其精简的配置
Adafruit_SSD1306 d(128, 64, &Wire, -1);

void UART_Init() {
    RCC->IOPENR |= 1; 
    RCC->APBENR1 |= (1 << 17);
    GPIOA->MODER &= ~(3 << 4); GPIOA->MODER |= (2 << 4);
    GPIOA->AFR[0] &= ~(0xF << 8); GPIOA->AFR[0] |= (1 << 8);
    USART2->BRR = 417; 
    USART2->CR1 |= 9; 
}

void p(const char *s) { // 缩减函数名以节省空间
    while (*s) {
        while (!(USART2->ISR & (1 << 7)));
        USART2->TDR = *s++;
    }
}

void setup() {
    UART_Init();
    // 硬件寄存器初始化
    RCC->APBENR2 |= (1 << 20);      
    GPIOA->MODER |= 3; 
    ADC1->CHSELR |= 1; ADC1->CR |= 1;
    while (!(ADC1->ISR & 1)); 

    RCC->APBENR2 |= (1 << 11);
    GPIOA->MODER &= ~(3 << 16); GPIOA->MODER |= (2 << 16);
    GPIOA->AFR[1] &= ~0xF; GPIOA->AFR[1] |= 2;
    TIM1->PSC = 47; TIM1->ARR = 1000;
    TIM1->CCMR1 |= 0x68; TIM1->CCER |= 1;
    TIM1->BDTR |= 0x8000; TIM1->CR1 |= 1;

    d.begin(SSD1306_SWITCHCAPVCC, 0x3C);
}

void loop() {
    ADC1->CR |= 4;
    while (!(ADC1->ISR & 4));
    uint32_t v = ADC1->DR;

    TIM1->CCR1 = (v * 1000) >> 12; // 使用位移代替除法

    // 2. 极其精简的显示逻辑
    d.clearDisplay();
    d.setCursor(0, 0);
    d.setTextColor(1);
    d.print(v); // 只显示数字

    // 发送最简单的数据包
    char m[10];
    utoa(v, m, 10); // 使用更轻量的 utoa 代替 sprintf
    p(m); p("\n");

    d.display();
    for(volatile int i=0; i<50000; i++); 
}