STM32-24位AD7799驅動之手冊代碼詳解,支持模擬SPI和硬件SPI

時間 2019-11-06

標籤 stm32 stm ad7799 驅動手冊代碼詳解支持模擬 spi 硬件简体版

原文原文鏈接

1.AD7799介紹函數

AD7799結構圖以下所示:測試

其中REFIN參考電壓建議爲2.5V, REFIN電壓低於0.1V時,則差分輸入ad值就沒法檢測了,以下圖所示:spa

注意:.net

若是REG_CONFIG的REF_DET開啓的話,那麼輸入AD值電壓低於0.5V時,則差分輸入ad值就沒法檢測了,以下圖所示:code

2.AD7799差分信號的輸入模式blog

以下圖所示,差分輸入電壓有3種模式:get

注意:it

單端輸入電壓(AIN-接地,只有正電壓)則支持任意範圍,好比In-Amp模式下,單端輸入若是爲10mv的話,也能檢測到.io

2.1 Unbuffered Mode非緩衝模式class

該模式可測的AD值能夠在 -30mV ~ (AVDD+30mv)範圍之間,若是開了雙極型模式(雙極型模式經過將REG_CONFIG的U/B位設0實現),則也能夠測-(AVDD+30mv)~30mV之間AD值.

也就是說假如咱們要測的AD值位於-100mV~100mV之間,則用這個模式.

該模式優缺點:可測範圍最大,可是精度偏差不是很高

2.2 Buffered Mode緩衝模式

緩衝的做用就是減小測的AD偏差,而且功耗相應地會增高點,該模式主要是測100mV~( AVDD-100mV)之間.

該模式優缺點:可測範圍比Unbuffered小一點,而且精度偏差高一點

2.3 In-Amp 高增益模式

須要將REG_CONFIG的Gain調到4及以上纔是該模式,不然的話,就會根據REG_CONFIG的BUF位來自動判斷是Buffered Mode仍是Unbuffered Mode.

而且AD值必須位於300mv~(AVDD+1100mv)之間,不然的話該模式是沒法檢測AD值的,以前筆者就是測差分輸入的正負20mV,卻一直沒有反應,後來才發現是處於這個模式的緣由.

該模式優缺點:可測範圍能夠經過設置Gain來設置測試範圍,好比VREF爲3V,Gain=4,則可測量程爲正負600mv.

注意:

當使用Buffered Mode或者In-Amp模式時,須要將REG_CONFIG的BO位開啓,介紹以下圖所示:

3.代碼效果

串口截圖以下:

經過電壓發生器不停修改AD值時,能夠看到萬用表和串口打印的數據相差不大:

PS:因爲GIF錄製的像素位數過低,因此不清晰

4.代碼實現

支持硬件SPI1或者GPIO模擬方式

代碼經過宏AD7799_INTERFACE_MODE判斷,可以支持硬件SPI1或者GPIO模擬方式,以下圖所示:

經過宏定義VREF參考電壓,以及GAIN增益值

以下圖所示,只需修改下面宏,就能夠實現轉換電壓數據自動轉換:

實現通道1和通道2來回切換

串口發送select 1,表示選擇通道1:

發送select 2,則表示選擇通道2.

4.1初始化過程

　　　　　/*ad7799初始化*/

         AD7799_gpio_init();
         while(!AD7799_Init())
         {
                          LED0 = !LED0;
                          delay_ms(50);
         }      
         LED0 = 1;
         AD7799_Calibrate();                           //通道校準

         AD7799_SetGain(AD7799_CHIP_GAIN);               
         AD7799_SetBurnoutCurren(0);                  //關閉BO
         AD7799_SetBufMode(0);                        //因爲咱們要測的電壓低於100mV,因此設置爲Unbuffered Mode
         AD7799_SetChannel(ChannelBuf[0]);            //通道設置.
         AD7799_SetMode(AD7799_MODE_CONT,5);          //默認雙極性   頻率爲5
         AD7799_SetReference(0);                      //關閉參考檢測,由於咱們的 AD7799_RefmV 參考電壓低於0.5V

4.2 上面的函數以下所示:

void AD7799_gpio_init(void) { GPIO_InitTypeDef GPIO_InitStructure; GPIO_InitStructure.GPIO_Pin = AD_CS_PIN; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(AD_CS_GPIO, &GPIO_InitStructure);                              //CS片選

#if ( AD7799_INTERFACE_MODE == AD7799_INTERFACE_SPI1 )
         //spi1 mode SPI1_Init(); SPI1_SetSpeed(SPI_BaudRatePrescaler_2); #else
         //gpio模擬spi mode GPIO_InitStructure.GPIO_Pin = AD_DI_PIN; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(AD_DI_GPIO, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = AD_SCK_PIN; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(AD_SCK_GPIO, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = AD_DO_PIN; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; GPIO_Init(AD_DO_GPIO, &GPIO_InitStructure); spi_AD7799_init(); #endif   AD7799_Reset(); } void AD7799_SetGain(unsigned long gain) { unsigned long command; command = AD7799_GetRegisterValue(AD7799_REG_CONF,2); command &= ~AD7799_CONF_GAIN(0xFF); command |= AD7799_CONF_GAIN(gain); AD7799_SetRegisterValue( AD7799_REG_CONF, command, 2 ); } void AD7799_SetBurnoutCurren(u8 enable)//設置BO { unsigned long command; command = AD7799_GetRegisterValue(AD7799_REG_CONF,2); command &= ~0X2000; if(enable) command |= 0X2000; AD7799_SetRegisterValue( AD7799_REG_CONF, command, 2 ); } void AD7799_SetBufMode(u8 enable)           //設置buf  { unsigned long command; command = AD7799_GetRegisterValue(AD7799_REG_CONF,2); command &= ~0X10;  if(enable) command |= 0X10; AD7799_SetRegisterValue( AD7799_REG_CONF, command, 2 ); } void AD7799_SetChannel(unsigned long channel) { unsigned long command; command = AD7799_GetRegisterValue(AD7799_REG_CONF,2); command &= ~AD7799_CONF_CHAN(0xFF); command |= AD7799_CONF_CHAN(channel); AD7799_SetRegisterValue( AD7799_REG_CONF, command, 2 ); } void AD7799_SetMode(unsigned long mode,u8 rate) { unsigned long command; command = AD7799_GetRegisterValue(AD7799_REG_MODE,2); command &= ~AD7799_MODE_SEL(0xFF); command |= AD7799_MODE_SEL(mode); command &= 0XFFF0; command |= rate;                   //設置頻率
 AD7799_SetRegisterValue( AD7799_REG_MODE, command, 2 ); } void AD7799_SetReference(unsigned char state) { unsigned long command = 0; command = AD7799_GetRegisterValue(AD7799_REG_CONF,2); command &= ~AD7799_CONF_REFDET(1); command |= AD7799_CONF_REFDET(state); AD7799_SetRegisterValue(AD7799_REG_CONF, command, 2); } void AD7799_SetRegisterValue(unsigned char regAddress, unsigned long regValue, unsigned char size) { unsigned char data[5] = {0x03, 0x00, 0x00, 0x00, 0x00}; data[0] = AD7799_COMM_WRITE | AD7799_COMM_ADDR(regAddress); if(size == 1) { data[1] = (unsigned char)regValue; } if(size == 2) { data[2] = (unsigned char)((regValue & 0x0000FF) >> 0); data[1] = (unsigned char)((regValue & 0x00FF00) >> 8); } if(size == 3) { data[3] = (unsigned char)((regValue & 0x0000FF) >> 0); data[2] = (unsigned char)((regValue & 0x00FF00) >> 8); data[1] = (unsigned char)((regValue & 0xFF0000) >> 16); } AD7799_CS_LOW; SPI_Write(data,(1 + size)); AD7799_CS_HIGH; } unsigned long AD7799_GetRegisterValue(unsigned char regAddress, unsigned char size) { unsigned char data[5] = {0x00, 0x00, 0x00, 0x00, 0x00}; unsigned long receivedData = 0x00; data[0] = AD7799_COMM_READ | AD7799_COMM_ADDR(regAddress); AD7799_CS_LOW; SPI_Write(data,1); SPI_Read(data,size); AD7799_CS_HIGH; if(size == 1) { receivedData += (data[0] << 0); } if(size == 2) { receivedData += (data[0] << 8); receivedData += (data[1] << 0); } if(size == 3) { receivedData += (data[0] << 16); receivedData += (data[1] << 8); receivedData += (data[2] << 0); } return receivedData; }

4.3 獲取通道電壓代碼以下所示:

　　　　　　while(1) { if(Serial_Post_ChannelValue!=0XFF)              //0:不選擇 1~2:更改通道 { CurrentChannelValue = Serial_Post_ChannelValue; Serial_Post_ChannelValue =0XFF; if(CurrentChannelValue && CurrentChannelValue<=2)        //1~2 { AD7799_SetChannel(ChannelBuf[CurrentChannelValue-1]);//通道設置. 0~1 delay_ms(10); AD7799_GetRegisterValue(AD7799_REG_DATA,3);//清空以前的AD } else if(CurrentChannelValue == 0) { printf("%s value0 0 0 \r\n",Board_Name); } } if(CurrentChannelValue)                  //選擇了通道？ { for(i=0;i<2;i++)                 //獲取每一個通道數據
                          if(CurrentChannelValue == (i+1)) { while( !AD7799_Ready())                //1~2 { delay_ms(5); } ADValues[i]=  analyzeAD7799_Data(AD7799_GetRegisterValue(AD7799_REG_DATA,3)); } else ADValues[i] = 0.0000; printf("%s 當前通道爲:%d %.3fmV %.3fmV \r\n",Board_Name,CurrentChannelValue,ADValues[0],ADValues[1]); } LED0 =!LED0; delay_ms(100); }