ADS1256+STM32程序详解_Python

ads1256是ti公司推出的微功耗、高精度、8通道、24位高性能模数转换器（adc）。该器件提供高达23比特的无噪声精度、数据速率高达30ksps（次采样/秒）、十万分之一的非线性特性以及具备众输入模拟多路开关、输入缓冲器、可编程增益放大器和可编程数字滤波器等，,有完善的自校正和系统校正系统,spi串行数据传输接口。可为设计人员带来完整而高分辨率的量测解决方，如应变计、气体分析、仪器仪表、压力传感器、血液分析、医疗科学仪器等应用，ads1256采用ssop-2封装。

ads1256特点

1、8通道输入：可同时采集8路信号。

2、测量范围广：0-5v输入电压采样

3、采集频率高，精度高：采集卡的采集速率为30k/s。

ads1256示意图

1．时序图

stm32spi可以直接连接，ads1256的cs线仅仅只是做片选使用数据输出结束需要发送一次脉冲。在sclk第一脉冲din开始接受数据输入，数据输入完毕的t6内sclk需要保持低电平，然后调制一个周期的脉冲信号，数据即可全部到达dout总线，一次读写完毕。

核心源码：

#include <stdio.h>
#include "stm32f10x_gpio.h"
#include "ads1256.h"

//***************************
//       pin assign
//           stm32           ads1256
//       gpiob_pin_11        <--- drdy
//       gpiob_pin_12        ---> cs
//       gpiob_pin_13        ---> sck
//       gpiob_pin_14(miso) <--- dout
//       gpiob_pin_15(mosi) ---> din
//***************************

#define rcc_drdy           rcc_apb2periph_gpiob
#define port_drdy           gpiob
#define pin_drdy           gpio_pin_11

#define port_cs gpiob
#define pin_cs gpio_pin_12

#define cs_0()               gpio_resetbits(port_cs, pin_cs);
#define cs_1()               gpio_setbits(port_cs, pin_cs);
#define ads1256_drdy         (port_drdy->idr & pin_drdy)

void spi2_init(void)
{
spi_inittypedef spi_initstructure;
gpio_inittypedef gpio_initstructure;
/****initial spi2******************/

/* enable spi2 and gpiob clocks */
rcc_apb2periphclockcmd(rcc_apb2periph_gpiob, enable);

rcc_apb1periphclockcmd(rcc_apb1periph_spi2, enable);
/* configure spi2 pins: nss, sck, miso and mosi */
gpio_initstructure.gpio_pin = gpio_pin_13 | gpio_pin_14 | gpio_pin_15;
gpio_initstructure.gpio_speed = gpio_speed_50mhz;
gpio_initstructure.gpio_mode = gpio_mode_af_pp;
gpio_init(gpiob, &gpio_initstructure);

/* spi2 configuration */
spi_initstructure.spi_direction = spi_direction_2lines_fullduplex; //
spi_initstructure.spi_mode = spi_mode_master;
spi_initstructure.spi_datasize = spi_datasize_8b;
spi_initstructure.spi_cpol = spi_cpol_low;
spi_initstructure.spi_cpha = spi_cpha_2edge;
spi_initstructure.spi_nss = spi_nss_soft;
spi_initstructure.spi_baudrateprescaler = spi_baudrateprescaler_256; //
spi_initstructure.spi_firstbit = spi_firstbit_msb;
spi_initstructure.spi_crcpolynomial = 7;
spi_init(spi2, &spi_initstructure);
/* enable spi2 */
spi_cmd(spi2, enable);
}

void init_ads1256_gpio(void)
{
gpio_inittypedef gpio_initstructure;
rcc_apb2periphclockcmd(rcc_drdy, enable);

   gpio_initstructure.gpio_pin = pin_drdy;
   gpio_initstructure.gpio_mode = gpio_mode_ipu;
   gpio_initstructure.gpio_speed = gpio_speed_50mhz;
   gpio_init(port_drdy, &gpio_initstructure);
   //spi2 nss
   cs_1();
gpio_initstructure.gpio_pin = pin_cs;
gpio_initstructure.gpio_speed = gpio_speed_50mhz;
gpio_initstructure.gpio_mode = gpio_mode_out_pp;
gpio_init(port_cs, &gpio_initstructure);

   spi2_init();
}

unsigned char spi_writebyte(unsigned char txdata)
{
unsigned char rxdata=0;
while(spi_i2s_getflagstatus(spi2,spi_i2s_flag_txe)==reset);
spi_i2s_senddata(spi2,txdata);
while(spi_i2s_getflagstatus(spi2,spi_i2s_flag_rxne)==reset);
rxdata=spi_i2s_receivedata(spi2);
return rxdata;
}

void ads1256wreg(unsigned char regaddr,unsigned char databyte)
{

   cs_0();
   while(ads1256_drdy);

spi_writebyte(ads1256_cmd_wreg | (regaddr & 0x0f));

spi_writebyte(0x00);

spi_writebyte(databyte);
   cs_1();
}

//³õê¼»¯ads1256
void ads1256_init(void)
{
   //*************×ôð£×¼****************
    while(ads1256_drdy);
   cs_0();
   spi_writebyte(ads1256_cmd_selfcal);
   while(ads1256_drdy);
   cs_1();
   //**********************************

ads1256wreg(ads1256_status,0x06);
// ads1256wreg(ads1256_status,0x04);

//   ads1256wreg(ads1256_mux,0x08); ¡¯
   ads1256wreg(ads1256_adcon,ads1256_gain_1);
   ads1256wreg(ads1256_drate,ads1256_drate_10sps);
   ads1256wreg(ads1256_io,0x00);

   //*************************
   while(ads1256_drdy);
   cs_0();
   spi_writebyte(ads1256_cmd_selfcal);
   while(ads1256_drdy);
   cs_1();
   //**********************************
}