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【嵌入式硬件芯片开发笔记】HART协议调制解调芯片AD5700配置流程
XTAL_EN接地，CLK_CFG的两个引脚由同一个GPIO控制
初始时HART_CLK_CFG输出低电平
由RTS引脚控制调制/解调。当RTS处于高电平时，为解调（输入）；否则为调制（输出）。切换时，延时1ms
HART协议部分，符合HART物理层要求(修订版8.1)。
一个标准UART帧，该帧包含一个起始位、8位数据、一个奇偶校验和一个停止位
UART：1200波特率 1停止位 无校验 数据长度8
开始运行
- 检测HART_VDD，至少大于2.7V
- 引脚HART_CLK_CFG初始时为低电平，拉高后CLKOUT输出1.2288MHz，用定时器进行捕获，计算频率是否达标
- 最后开启调制或解调
初始化 - 使能CFG引脚，进行时钟检测
- 采用定时器捕获的方式计算频率（计算速度不够则可能算不准）
- 关闭CFG引脚
- 解调模式接收数据
- 当串口接收中断发生时，解析命令并切换调制模式，返回数据
代码例程
uint8_t UART4_RxBuffer[256]={0};
uint8_t UART4_RxFlag=0;
/*** @brief UART4 Initialization Function* @param None* @retval None*/
static void MX_UART4_Init(void)
{/* USER CODE BEGIN UART4_Init 0 *//* USER CODE END UART4_Init 0 *//* USER CODE BEGIN UART4_Init 1 *//* USER CODE END UART4_Init 1 */huart4.Instance = UART4;huart4.Init.BaudRate = 1200;huart4.Init.WordLength = UART_WORDLENGTH_8B;huart4.Init.StopBits = UART_STOPBITS_1;huart4.Init.Parity = UART_PARITY_NONE;huart4.Init.Mode = UART_MODE_TX_RX;huart4.Init.HwFlowCtl = UART_HWCONTROL_NONE;huart4.Init.OverSampling = UART_OVERSAMPLING_16;huart4.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;huart4.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;if (HAL_UART_Init(&huart4) != HAL_OK){Error_Handler();}/* USER CODE BEGIN UART4_Init 2 */HAL_UART_Receive_IT(&huart4,UART4_RxBuffer,1);/* USER CODE END UART4_Init 2 */}
/*!* @brief 初始化AD5421** @param None** @return None*/
void Init_AD5421(void)
{ uint16_t offset = 0;uint16_t gain = 0;Ctrl_AD5421(&hspi2,AD5421_RESET,0,true);delay_us(50);Ctrl_AD5421(&hspi2,AD5421_Control,0xFC00,true); offset = Ctrl_AD5421(&hspi2,AD5421_Offset_Adjust,0,false); gain = Ctrl_AD5421(&hspi2,AD5421_Gain_Adjust,0,false);Ctrl_AD5421_DAC(20,true,offset,gain);Ctrl_AD5421_ADC(1,true);Ctrl_AD5421_ADC(0,true);
}/*!* @brief 使能HART_CLK_OUT的定时器，用于输入捕获，上升沿捕获，4次有效** @param None** @return freq: 浮点型频率变量，单位为Hz*/
float Get_HART_CLK_Cycle(void)
{uint32_t Count=0;float freq=0;TIM3_CH2_Flag=0;TIM3_CH2_Overflow=0;TIM3_CH2_Count[0]=0;TIM3_CH2_Count[1]=0; TIM_RESET_CAPTUREPOLARITY(&htim3,TIM_CHANNEL_2); __HAL_TIM_SET_CAPTUREPOLARITY(&htim3, TIM_CHANNEL_2, TIM_INPUTCHANNELPOLARITY_FALLING); HAL_TIM_Base_Start_IT(&htim3);HAL_TIM_IC_Start_IT(&htim3, TIM_CHANNEL_2);while(TIM3_CH2_Flag<2);TIM3_CH2_Flag=0;Count=TIM3_CH2_Overflow*(0xFFFF+1)+TIM3_CH2_Count[1]-TIM3_CH2_Count[0]; freq=50000000.0f/Count;TIM3_CH2_Overflow=0;TIM3_CH2_Count[0]=0;TIM3_CH2_Count[1]=0;printf("[INFO] HART_CLK: %0.4f Hz\n",freq);return freq;
}/*!* @brief 操作AD5700的HART调制/解调** @param [in] dat_buf: 要写入的数据，可以填NULL* [in] size: 要写入的数据个数，单位byte* [in] WriteNotRead: true，写入（调制），发送UART数据然后通过HART发出来* false，读取（解调），接收HART数据，解调以后以中断的方式接收UART数据** @return None*/
void Ctrl_AD5700_HART(uint8_t *dat_buf,uint8_t size,bool WriteNotRead)
{if(WriteNotRead){Disable_AD5700_RTS;delay_ms(1);HAL_UART_Transmit(&huart4,dat_buf,size,0xFFFF);}else{Enable_AD5700_RTS;delay_ms(1);HAL_UART_Receive_IT(&huart4,&UART4_RxBuffer[UART4_RxFlag],1); //开启中断 填入的buf最好是HART专用的数据buf 全局变量 然后在回调里面也改成HART的buf}
}/*!* @brief 初始化AD5700** @param None** @return None*/
void Init_AD5700(void)
{//ADC检测 Enable_HART_CLK_CFG;
// //时钟检测
// Get_HART_CLK_Cycle();// Disable_HART_CLK_CFG;Ctrl_AD5700_HART(NULL,0,false);
}
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{if(huart==&huart2){ HAL_UART_Transmit(&huart2,&RxBuffer,1,0xFFFF);HAL_UART_Receive_IT(&huart2,&RxBuffer,1);}else if(huart==&huart3){ HAL_UART_Transmit(&huart3,&RxBuffer,1,0xFFFF);HAL_UART_Receive_IT(&huart3,&RxBuffer,1);}else if(huart==&huart4){
// HAL_UART_Transmit(&huart4,&UART4_RxBuffer[UART4_RxFlag],1,0xFFFF);UART4_RxFlag++;HAL_UART_Receive_IT(&huart4,&UART4_RxBuffer[UART4_RxFlag],1);}else if(huart==&huart5){ HAL_UART_Transmit(&huart5,&RxBuffer,1,0xFFFF);if((RxBuffer>>5)==6){load_dac=(RxBuffer&0x1F);}HAL_UART_Receive_IT(&huart5,&RxBuffer,1);}
}