//***************************
//		Pin assign	   	
//		STM32f407			ADS1256		
//		GPIOA_Pin_3 		<--- DRDY
//		GPIOA_Pin_1 		---> CS
//		GPIOA_Pin_5 		---> SCK
//		GPIOA_Pin_6(MISO)  <--- DOUT
//		GPIOA_Pin_7(MOSI)  ---> DIN
//***************************	
#include "ads1256.h"
#define ADS1256_GPIO GPIOA
#define ADS1256_DRDY GPIO_PIN_3
#define ADS1256_CS GPIO_PIN_1
extern SPI_HandleTypeDef hspi1;
//-----------------------------------------------------------------//
//	功    能：  SPI通信
//	入口参数: /	发送的SPI数据
//	出口参数: /	接收的SPI数据
//	全局变量: /
//	备    注: 	发送接收函数
//-----------------------------------------------------------------//
unsigned char SPI_WriteByte(unsigned char TxData)
{
  unsigned char RxData=0;
	HAL_SPI_TransmitReceive(&hspi1, &TxData, &RxData, 1, 10);
  return RxData;
}
//-----------------------------------------------------------------//
//	功    能：ADS1256 写数据
//	入口参数: /
//	出口参数: /
//	全局变量: /
//	备    注: 向ADS1256中地址为regaddr的寄存器写入一个字节databyte
//-----------------------------------------------------------------//
void ADS1256WREG(unsigned char regaddr,unsigned char databyte)  //ADS1256WREG(ADS1256_MUX,channel);		//设置通道
{
  HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_RESET);  
//	CS_0();
	while(HAL_GPIO_ReadPin (ADS1256_GPIO,ADS1256_DRDY)==1) {}	
	//当ADS1256_DRDY为低时才能写寄存器
	//向寄存器写入数据地址
	SPI_WriteByte(ADS1256_CMD_WREG | (regaddr & 0x0F));
	//写入数据的个数n-1
	SPI_WriteByte(0x00);
	//向regaddr地址指向的寄存器写入数据databyte
	SPI_WriteByte(databyte);
	HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_SET);  
}
//初始化ADS1256
float ADS1256_GAIN = 1.0f;
void ADS1256_Init(uint8_t gain) {
	//*************自校准****************
//  while(HAL_GPIO_ReadPin (ADS1256_GPIO,ADS1256_DRDY)==1);
//	HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_RESET); 
//	SPI_WriteByte(ADS1256_CMD_SELFCAL);
//	while(HAL_GPIO_ReadPin (ADS1256_GPIO,ADS1256_DRDY)==1);
//	HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_SET);  
	//**********************************
//	ADS1256WREG(ADS1256_STATUS,0x06);               // 高位在前、使用缓冲
	ADS1256WREG(ADS1256_STATUS,0x04);               // 高位在前、不使用缓冲
	ADS1256WREG(ADS1256_MUX,0x08);                  // 初始化端口A0为‘+’，AINCOM位‘-’
	if(gain == ADS1256_GAIN_1) ADS1256_GAIN = 1.0f;		// 放大倍数1 ±5V
	if(gain == ADS1256_GAIN_2) ADS1256_GAIN = 2.0f;		// 放大倍数2 ±2.5V
	if(gain == ADS1256_GAIN_4) ADS1256_GAIN = 4.0f;		// 放大倍数4 ±1.25V
	if(gain == ADS1256_GAIN_8) ADS1256_GAIN = 8.0f;		// 放大倍数8 ±0.625V
	if(gain == ADS1256_GAIN_16) ADS1256_GAIN = 16.0f;	// 放大倍数16 ±0.3125V
	if(gain == ADS1256_GAIN_32) ADS1256_GAIN = 32.0f;	// 放大倍数32 ±0.15625V
	if(gain == ADS1256_GAIN_64) ADS1256_GAIN = 64.0f;	// 放大倍数64 ±0.078125V
		ADS1256WREG(ADS1256_ADCON, gain);                // 放大倍数8 ±0.625V
//	ADS1256WREG(ADS1256_ADCON,ADS1256_GAIN_1);                // 放大倍数1 ±5V
//	ADS1256WREG(ADS1256_ADCON,ADS1256_GAIN_4);                // 放大倍数4 ±1.25V
//	ADS1256WREG(ADS1256_ADCON,ADS1256_GAIN_8);                // 放大倍数8 ±0.625V
//	ADS1256WREG(ADS1256_ADCON,ADS1256_GAIN_16);                // 放大倍数8 ±0.3125V
	ADS1256WREG(ADS1256_DRATE,ADS1256_DRATE_1000SPS);  // 数据10sps
	ADS1256WREG(ADS1256_IO,0x00);               
	//*************自校准****************
	while(HAL_GPIO_ReadPin (ADS1256_GPIO,ADS1256_DRDY)==1);
	HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_RESET); 
	SPI_WriteByte(ADS1256_CMD_SELFCAL);
	while(HAL_GPIO_ReadPin (ADS1256_GPIO,ADS1256_DRDY)==1);
	HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_SET);  
	//**********************************
}
// 微秒级延迟（纯循环）
void delay_us(uint32_t us) {
    us *= 40; // 校准值（需根据实际测试调整）
    while (us--) {
        __asm__ volatile ("nop"); // 插入空指令确保循环不被优化
    }
}
// 毫秒级延迟（基于delay_us）
void delay_ms(uint32_t ms) {
    while (ms--) {
        delay_us(1000);
    }
}
//读取AD值
unsigned char pre_channel = 0;
int ADS1256ReadData(unsigned char channel) {
  unsigned int sum=0;
	while(HAL_GPIO_ReadPin(ADS1256_GPIO,ADS1256_DRDY)==1);//当ADS1256_DRDY为低时才能写寄存器 
	if (pre_channel != channel) {
		pre_channel = channel;
		HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_RESET); 
		ADS1256WREG(ADS1256_MUX,channel);		//设置通道
		HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_SET); 
		HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_RESET);
		SPI_WriteByte(ADS1256_CMD_SYNC);
		SPI_WriteByte(ADS1256_CMD_WAKEUP);
		HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_SET);
		while (HAL_GPIO_ReadPin(ADS1256_GPIO, ADS1256_DRDY) == 1);
	}
		HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_RESET);
	SPI_WriteByte(ADS1256_CMD_RDATA);
//	HAL_Delay(1);
  delay_us(10);
		sum |= (SPI_WriteByte(0xff) << 16);
	sum |= (SPI_WriteByte(0xff) << 8);
	sum |= SPI_WriteByte(0xff);
	HAL_GPIO_WritePin(ADS1256_GPIO, ADS1256_CS, GPIO_PIN_SET); 
	if (sum>0x7FFFFF)           // if MSB=1, 
	{
		sum -= 0x1000000;       // do 2's complement
	}
    return sum;
}
double ADS1256ReadVoltage(unsigned char channel) {
	double voltage = ADS1256ReadData(channel)*(double)0.000000598;
	voltage /= ADS1256_GAIN;
	return voltage;
}