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.h
- Committer:
- ykuroda
- Date:
- 2012-08-29
- Revision:
- 2:a547c48d2152
- Parent:
- 1:ac3b7f978aa3
- Child:
- 3:b7e72acaade2
File content as of revision 2:a547c48d2152:
// // AD7490 ... Analog Devices 16 channels, 1MSPS, 12bit ADC // // 2012.08.29 ... Originaly written by Yoji KURODA // #ifndef _AD7490_H #define _AD7490_H class AD7490 { protected: enum CREG { CREG_WRITE = 0x800, CREG_SEQ = 0x400, CREG_ADD3 = 0x200, CREG_ADD2 = 0x100, CREG_ADD1 = 0x080, CREG_ADD0 = 0x040, CREG_PM1 = 0x020, CREG_PM0 = 0x010, CREG_SHADOW = 0x008, CREG_WEAK = 0x004, CREG_RANGE = 0x002, CREG_CODING = 0x001 }; SPI spi; DigitalOut cs; public: AD7490(SPI _spi, PinName _cs); ~AD7490(); unsigned short convert(int ch=0); void convert(short data[]); unsigned short sequential(int ch=15); unsigned short read(void); void read(short data[]); }; #endif // _AD7490_H