EEPROM 掉电保存

// 保存：写 3 字节配置到 AT24C02 地址 0x10
uint8_t cfg[3] = {baud_cfg, mode_cfg, calib_cfg};
HAL_I2C_Mem_Write(&hi2c1, (0xA0 >> 1) | 0, 0x10,
                  I2C_MEMADD_SIZE_8BIT, cfg, 3, 100);
HAL_Delay(6);   // 等写周期完成

// 恢复：上电时读回
uint8_t saved[3] = {0};
HAL_I2C_Mem_Read(&hi2c1, (0xA0 >> 1) | 0, 0x10,
                 I2C_MEMADD_SIZE_8BIT, saved, 3, 100);