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@2:a547c48d2152, 2012-08-29 (annotated)

Committer:
ykuroda
Date:
Wed Aug 29 14:19:06 2012 +0000
Revision:
2:a547c48d2152
Parent:
1:ac3b7f978aa3
Child:
4:f059fdd25051
Comments inserted.

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 AD7490::~AD7490()
ykuroda 0:95be7403a10c 39 {
ykuroda 0:95be7403a10c 40 }
ykuroda 0:95be7403a10c 41
ykuroda 0:95be7403a10c 42 unsigned short
ykuroda 0:95be7403a10c 43 AD7490::convert(int ch)
ykuroda 0:95be7403a10c 44 {
ykuroda 0:95be7403a10c 45 unsigned short x = 0;
ykuroda 0:95be7403a10c 46
ykuroda 0:95be7403a10c 47 x |= CREG_WRITE;
ykuroda 0:95be7403a10c 48 // x |= CREG_SEQ;
ykuroda 0:95be7403a10c 49 // x |= CREG_SHADOW;
ykuroda 0:95be7403a10c 50 // x |= CREG_ADD3;
ykuroda 0:95be7403a10c 51 // x |= CREG_ADD2;
ykuroda 0:95be7403a10c 52 // x |= CREG_ADD1;
ykuroda 0:95be7403a10c 53 x |= (CREG_ADD0|CREG_ADD1|CREG_ADD2|CREG_ADD3) & (ch<<6);
ykuroda 0:95be7403a10c 54
ykuroda 0:95be7403a10c 55 x |= CREG_PM1;
ykuroda 0:95be7403a10c 56 x |= CREG_PM0;
ykuroda 0:95be7403a10c 57 x |= CREG_RANGE;
ykuroda 0:95be7403a10c 58 x |= CREG_CODING;
ykuroda 0:95be7403a10c 59
ykuroda 0:95be7403a10c 60 cs = 0;
ykuroda 1:ac3b7f978aa3 61 unsigned short ret = spi.write(x<<4);
ykuroda 0:95be7403a10c 62 cs = 1;
ykuroda 0:95be7403a10c 63
ykuroda 0:95be7403a10c 64 // printf("send = 0x%X, ch = %2d, ret = %d\n", x, (ret>>12)&0xF, ret&0xFFF);
ykuroda 0:95be7403a10c 65
ykuroda 0:95be7403a10c 66 return ret;
ykuroda 0:95be7403a10c 67 }
ykuroda 0:95be7403a10c 68
ykuroda 0:95be7403a10c 69 void
ykuroda 0:95be7403a10c 70 AD7490::convert(short data[])
ykuroda 0:95be7403a10c 71 {
ykuroda 0:95be7403a10c 72 for(int ch=0; ch<16; ch++) data[ch]=0;
ykuroda 0:95be7403a10c 73 for(int ch=0; ch<16; ch++){
ykuroda 0:95be7403a10c 74 unsigned short ret = convert(ch);
ykuroda 0:95be7403a10c 75
ykuroda 0:95be7403a10c 76 data[ ret>>12&0xF ] = ret&0xFFF;
ykuroda 0:95be7403a10c 77 }
ykuroda 0:95be7403a10c 78 }
ykuroda 0:95be7403a10c 79
ykuroda 0:95be7403a10c 80
ykuroda 0:95be7403a10c 81 unsigned short
ykuroda 0:95be7403a10c 82 AD7490::sequential(int ch)
ykuroda 0:95be7403a10c 83 {
ykuroda 0:95be7403a10c 84 unsigned short x = 0;
ykuroda 0:95be7403a10c 85
ykuroda 0:95be7403a10c 86 x |= CREG_WRITE;
ykuroda 0:95be7403a10c 87 x |= CREG_SEQ;
ykuroda 0:95be7403a10c 88 x |= CREG_SHADOW;
ykuroda 0:95be7403a10c 89 // x |= CREG_ADD3;
ykuroda 0:95be7403a10c 90 // x |= CREG_ADD2;
ykuroda 0:95be7403a10c 91 // x |= CREG_ADD1;
ykuroda 0:95be7403a10c 92 x |= (CREG_ADD0|CREG_ADD1|CREG_ADD2|CREG_ADD3) & (ch<<6);
ykuroda 0:95be7403a10c 93
ykuroda 0:95be7403a10c 94 x |= CREG_PM1;
ykuroda 0:95be7403a10c 95 x |= CREG_PM0;
ykuroda 0:95be7403a10c 96 x |= CREG_RANGE;
ykuroda 0:95be7403a10c 97 x |= CREG_CODING;
ykuroda 0:95be7403a10c 98
ykuroda 0:95be7403a10c 99 cs = 0;
ykuroda 1:ac3b7f978aa3 100 unsigned short ret = spi.write(x<<4);
ykuroda 0:95be7403a10c 101 cs = 1;
ykuroda 0:95be7403a10c 102
ykuroda 0:95be7403a10c 103 return ret;
ykuroda 0:95be7403a10c 104 }
ykuroda 0:95be7403a10c 105
ykuroda 0:95be7403a10c 106
ykuroda 0:95be7403a10c 107
ykuroda 0:95be7403a10c 108 unsigned short
ykuroda 0:95be7403a10c 109 AD7490::read(void)
ykuroda 0:95be7403a10c 110 {
ykuroda 0:95be7403a10c 111 unsigned short x = 0;
ykuroda 0:95be7403a10c 112
ykuroda 0:95be7403a10c 113 // x |= CREG_WRITE;
ykuroda 0:95be7403a10c 114 // x |= CREG_SEQ;
ykuroda 0:95be7403a10c 115 // x |= CREG_SHADOW;
ykuroda 0:95be7403a10c 116 // x |= CREG_ADD3;
ykuroda 0:95be7403a10c 117 // x |= CREG_ADD2;
ykuroda 0:95be7403a10c 118 // x |= CREG_ADD1;
ykuroda 0:95be7403a10c 119 // x |= (CREG_ADD0|CREG_ADD1|CREG_ADD2|CREG_ADD3) & (ch<<6);
ykuroda 0:95be7403a10c 120
ykuroda 0:95be7403a10c 121 // x |= CREG_PM1;
ykuroda 0:95be7403a10c 122 // x |= CREG_PM0;
ykuroda 0:95be7403a10c 123 // x |= CREG_RANGE;
ykuroda 0:95be7403a10c 124 // x |= CREG_CODING;
ykuroda 0:95be7403a10c 125
ykuroda 0:95be7403a10c 126 cs = 0;
ykuroda 1:ac3b7f978aa3 127 unsigned short ret = spi.write(x<<4);
ykuroda 0:95be7403a10c 128 cs = 1;
ykuroda 0:95be7403a10c 129
ykuroda 0:95be7403a10c 130 // printf("send = 0x%X, ch = %2d, ret = %d\n", x, (ret>>12)&0xF, ret&0xFFF);
ykuroda 0:95be7403a10c 131
ykuroda 0:95be7403a10c 132 return ret;
ykuroda 0:95be7403a10c 133 }
ykuroda 0:95be7403a10c 134
ykuroda 0:95be7403a10c 135 void
ykuroda 0:95be7403a10c 136 AD7490::read(short data[])
ykuroda 0:95be7403a10c 137 {
ykuroda 0:95be7403a10c 138 for(int ch=0; ch<16; ch++) data[ch]=0;
ykuroda 0:95be7403a10c 139 for(int ch=0; ch<16; ch++){
ykuroda 0:95be7403a10c 140 unsigned short ret = read();
ykuroda 0:95be7403a10c 141
ykuroda 0:95be7403a10c 142 data[ ret>>12&0xF ] = ret&0xFFF;
ykuroda 0:95be7403a10c 143 }
ykuroda 0:95be7403a10c 144 }