Yoji KURODA / AD7490

Analog Devices 16 channels, 1MSPS, 12bit ADC with SPI interface

Analog Devices' AD7490 A/D converter chip is a great choice to increase ADC channels to mbed. I wrote a C++ class library, which allows multiple chips on the same SPI serial bus line.

main.cpp - usage of sequential mode (use 2 ADCs)

#include "mbed.h"
#include "AD7490.h"

DigitalOut myled(LED1);
SPI spi(p11,p12,p13);

int main() {

    // set up SPI interface. 
    // should be set before call AD7490 constructer
    spi.format(16,0);
    spi.frequency(1000000);

    // construct AD7490 instances
    AD7490 ad1(spi, p9);
    AD7490 ad2(spi, p10);

    // start ad conversion with sequential mode
    ad1.sequential();
    ad2.sequential();

    while(1) {
        short ad_data[32];      // user buffer area

        myled = 1;
        ad1.read(&ad_data[ 0]);  // save the first ADC data to buffer
        ad2.read(&ad_data[16]);  // save the second ADC data to buffer
        myled = 0;

        for(int i=0; i<32; i++)
            printf("ch[%2d]: %d\n", i, ad_data[i]);
        puts("");
        
        wait(1);
    }
}

API

AD7490
AD7490(SPI _spi, PinName _cs)Constructor. needs SPI instance and the Chip select pin
unsigned short convert(int ch=0)Single channel (one shot) conversion.
void convert(short data[]);All channels conversion with multiple 'one shot conversion'
unsigned short sequential(int ch=15);Start sequential mode, from channel 0 to 'ch'. ch=15 is default
void read(short buffer[]);Read data channel [0] to [ch], and copy them to user buffer area

AD7490.cpp@4:f059fdd25051, 2012-09-24 (annotated)

Committer:
ykuroda
Date:
Mon Sep 24 21:47:05 2012 +0000
Revision:
4:f059fdd25051
Parent:
2:a547c48d2152 
set destructor virtual

Who changed what in which revision?

UserRevisionLine numberNew contents of line
ykuroda 2:a547c48d2152 1 //
ykuroda 2:a547c48d2152 2 // AD7490 ... Analog Devices 16 channels, 1MSPS, 12bit ADC
ykuroda 2:a547c48d2152 3 //
ykuroda 2:a547c48d2152 4 // 2012.08.29 ... Originaly written by Yoji KURODA
ykuroda 2:a547c48d2152 5 //
ykuroda 0:95be7403a10c 6 #include "mbed.h"
ykuroda 0:95be7403a10c 7 #include "AD7490.h"
ykuroda 0:95be7403a10c 8
ykuroda 0:95be7403a10c 9 AD7490::AD7490(SPI _spi, PinName _cs)
ykuroda 0:95be7403a10c 10 : spi(_spi),
ykuroda 0:95be7403a10c 11 cs(_cs)
ykuroda 0:95be7403a10c 12 {
ykuroda 1:ac3b7f978aa3 13 unsigned short x = 0;
ykuroda 0:95be7403a10c 14
ykuroda 0:95be7403a10c 15 for(int i=0; i<3; i++){
ykuroda 0:95be7403a10c 16
ykuroda 0:95be7403a10c 17 x = 0;
ykuroda 0:95be7403a10c 18 x |= CREG_WRITE;
ykuroda 0:95be7403a10c 19 // x |= CREG_SEQ;
ykuroda 0:95be7403a10c 20 // x |= CREG_SHADOW;
ykuroda 0:95be7403a10c 21 x |= CREG_ADD3;
ykuroda 0:95be7403a10c 22 x |= CREG_ADD2;
ykuroda 0:95be7403a10c 23 x |= CREG_ADD1;
ykuroda 0:95be7403a10c 24 x |= CREG_ADD0;
ykuroda 0:95be7403a10c 25 x |= CREG_PM1;
ykuroda 0:95be7403a10c 26 x |= CREG_PM0;
ykuroda 0:95be7403a10c 27 x |= CREG_RANGE;
ykuroda 0:95be7403a10c 28 x |= CREG_CODING;
ykuroda 0:95be7403a10c 29
ykuroda 0:95be7403a10c 30 cs = 0;
ykuroda 1:ac3b7f978aa3 31 unsigned short ret = spi.write(x<<4);
ykuroda 0:95be7403a10c 32 cs = 1;
ykuroda 0:95be7403a10c 33
ykuroda 0:95be7403a10c 34 // printf("INIT: send = 0x%X, ret = 0x%X\n", x, ret);
ykuroda 0:95be7403a10c 35 }
ykuroda 0:95be7403a10c 36 }
ykuroda 0:95be7403a10c 37
ykuroda 0:95be7403a10c 38 unsigned short
ykuroda 0:95be7403a10c 39 AD7490::convert(int ch)
ykuroda 0:95be7403a10c 40 {
ykuroda 0:95be7403a10c 41 unsigned short x = 0;
ykuroda 0:95be7403a10c 42
ykuroda 0:95be7403a10c 43 x |= CREG_WRITE;
ykuroda 0:95be7403a10c 44 // x |= CREG_SEQ;
ykuroda 0:95be7403a10c 45 // x |= CREG_SHADOW;
ykuroda 0:95be7403a10c 46 // x |= CREG_ADD3;
ykuroda 0:95be7403a10c 47 // x |= CREG_ADD2;
ykuroda 0:95be7403a10c 48 // x |= CREG_ADD1;
ykuroda 0:95be7403a10c 49 x |= (CREG_ADD0|CREG_ADD1|CREG_ADD2|CREG_ADD3) & (ch<<6);
ykuroda 0:95be7403a10c 50
ykuroda 0:95be7403a10c 51 x |= CREG_PM1;
ykuroda 0:95be7403a10c 52 x |= CREG_PM0;
ykuroda 0:95be7403a10c 53 x |= CREG_RANGE;
ykuroda 0:95be7403a10c 54 x |= CREG_CODING;
ykuroda 0:95be7403a10c 55
ykuroda 0:95be7403a10c 56 cs = 0;
ykuroda 1:ac3b7f978aa3 57 unsigned short ret = spi.write(x<<4);
ykuroda 0:95be7403a10c 58 cs = 1;
ykuroda 0:95be7403a10c 59
ykuroda 0:95be7403a10c 60 // printf("send = 0x%X, ch = %2d, ret = %d\n", x, (ret>>12)&0xF, ret&0xFFF);
ykuroda 0:95be7403a10c 61
ykuroda 0:95be7403a10c 62 return ret;
ykuroda 0:95be7403a10c 63 }
ykuroda 0:95be7403a10c 64
ykuroda 0:95be7403a10c 65 void
ykuroda 0:95be7403a10c 66 AD7490::convert(short data[])
ykuroda 0:95be7403a10c 67 {
ykuroda 0:95be7403a10c 68 for(int ch=0; ch<16; ch++) data[ch]=0;
ykuroda 0:95be7403a10c 69 for(int ch=0; ch<16; ch++){
ykuroda 0:95be7403a10c 70 unsigned short ret = convert(ch);
ykuroda 0:95be7403a10c 71
ykuroda 0:95be7403a10c 72 data[ ret>>12&0xF ] = ret&0xFFF;
ykuroda 0:95be7403a10c 73 }
ykuroda 0:95be7403a10c 74 }
ykuroda 0:95be7403a10c 75
ykuroda 0:95be7403a10c 76
ykuroda 0:95be7403a10c 77 unsigned short
ykuroda 0:95be7403a10c 78 AD7490::sequential(int ch)
ykuroda 0:95be7403a10c 79 {
ykuroda 0:95be7403a10c 80 unsigned short x = 0;
ykuroda 0:95be7403a10c 81
ykuroda 0:95be7403a10c 82 x |= CREG_WRITE;
ykuroda 0:95be7403a10c 83 x |= CREG_SEQ;
ykuroda 0:95be7403a10c 84 x |= CREG_SHADOW;
ykuroda 0:95be7403a10c 85 // x |= CREG_ADD3;
ykuroda 0:95be7403a10c 86 // x |= CREG_ADD2;
ykuroda 0:95be7403a10c 87 // x |= CREG_ADD1;
ykuroda 0:95be7403a10c 88 x |= (CREG_ADD0|CREG_ADD1|CREG_ADD2|CREG_ADD3) & (ch<<6);
ykuroda 0:95be7403a10c 89
ykuroda 0:95be7403a10c 90 x |= CREG_PM1;
ykuroda 0:95be7403a10c 91 x |= CREG_PM0;
ykuroda 0:95be7403a10c 92 x |= CREG_RANGE;
ykuroda 0:95be7403a10c 93 x |= CREG_CODING;
ykuroda 0:95be7403a10c 94
ykuroda 0:95be7403a10c 95 cs = 0;
ykuroda 1:ac3b7f978aa3 96 unsigned short ret = spi.write(x<<4);
ykuroda 0:95be7403a10c 97 cs = 1;
ykuroda 0:95be7403a10c 98
ykuroda 0:95be7403a10c 99 return ret;
ykuroda 0:95be7403a10c 100 }
ykuroda 0:95be7403a10c 101
ykuroda 0:95be7403a10c 102
ykuroda 0:95be7403a10c 103
ykuroda 0:95be7403a10c 104 unsigned short
ykuroda 0:95be7403a10c 105 AD7490::read(void)
ykuroda 0:95be7403a10c 106 {
ykuroda 0:95be7403a10c 107 unsigned short x = 0;
ykuroda 0:95be7403a10c 108
ykuroda 0:95be7403a10c 109 // x |= CREG_WRITE;
ykuroda 0:95be7403a10c 110 // x |= CREG_SEQ;
ykuroda 0:95be7403a10c 111 // x |= CREG_SHADOW;
ykuroda 0:95be7403a10c 112 // x |= CREG_ADD3;
ykuroda 0:95be7403a10c 113 // x |= CREG_ADD2;
ykuroda 0:95be7403a10c 114 // x |= CREG_ADD1;
ykuroda 0:95be7403a10c 115 // x |= (CREG_ADD0|CREG_ADD1|CREG_ADD2|CREG_ADD3) & (ch<<6);
ykuroda 0:95be7403a10c 116
ykuroda 0:95be7403a10c 117 // x |= CREG_PM1;
ykuroda 0:95be7403a10c 118 // x |= CREG_PM0;
ykuroda 0:95be7403a10c 119 // x |= CREG_RANGE;
ykuroda 0:95be7403a10c 120 // x |= CREG_CODING;
ykuroda 0:95be7403a10c 121
ykuroda 0:95be7403a10c 122 cs = 0;
ykuroda 1:ac3b7f978aa3 123 unsigned short ret = spi.write(x<<4);
ykuroda 0:95be7403a10c 124 cs = 1;
ykuroda 0:95be7403a10c 125
ykuroda 0:95be7403a10c 126 // printf("send = 0x%X, ch = %2d, ret = %d\n", x, (ret>>12)&0xF, ret&0xFFF);
ykuroda 0:95be7403a10c 127
ykuroda 0:95be7403a10c 128 return ret;
ykuroda 0:95be7403a10c 129 }
ykuroda 0:95be7403a10c 130
ykuroda 0:95be7403a10c 131 void
ykuroda 0:95be7403a10c 132 AD7490::read(short data[])
ykuroda 0:95be7403a10c 133 {
ykuroda 0:95be7403a10c 134 for(int ch=0; ch<16; ch++) data[ch]=0;
ykuroda 0:95be7403a10c 135 for(int ch=0; ch<16; ch++){
ykuroda 0:95be7403a10c 136 unsigned short ret = read();
ykuroda 0:95be7403a10c 137
ykuroda 0:95be7403a10c 138 data[ ret>>12&0xF ] = ret&0xFFF;
ykuroda 0:95be7403a10c 139 }
ykuroda 0:95be7403a10c 140 }