Tyari Taylor / Mbed OS SPI_MCP3002_OS

operational SPI with OS5

main.cpp@67:f141b2ad5fcd, 2018-08-23 (annotated)

Committer:
Tyari21
Date:
Thu Aug 23 14:07:02 2018 +0000
Revision:
67:f141b2ad5fcd
Parent:
66:0a43d8aeeb76 
operational SPI with OS5

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Jonathan Austin 0:2757d7abb7d9 1 #include "mbed.h"
Tyari21 67:f141b2ad5fcd 2 // Bits are: Start (1), SGL/DIFF (1 for single), ODD/SIGN (0 for channel 0), MSBF (1 for MSB first)
Tyari21 67:f141b2ad5fcd 3 #define MCP3002_CH0 0x68 // 0110 1000
Tyari21 67:f141b2ad5fcd 4 #define MCP3002_CH1 0x78 // 0111 1000
Jonathan Austin 0:2757d7abb7d9 5
Tyari21 67:f141b2ad5fcd 6 Serial pc(USBTX, USBRX);
Tyari21 67:f141b2ad5fcd 7 SPI spi(p5, p6, p7); // mosi, miso, sclk
Tyari21 67:f141b2ad5fcd 8 DigitalOut cs(p20); // Chip select, active low
Tyari21 67:f141b2ad5fcd 9 AnalogOut aout(p18);
Jonathan Austin 0:2757d7abb7d9 10
Tyari21 67:f141b2ad5fcd 11 // Note that using CS means that the chip itself has no address
Tyari21 67:f141b2ad5fcd 12
Jonathan Austin 0:2757d7abb7d9 13 int main() {
Tyari21 67:f141b2ad5fcd 14 pc.printf("Starting program \r\n");
Tyari21 67:f141b2ad5fcd 15 // Chip must be deselected
Tyari21 67:f141b2ad5fcd 16 cs = 1;
Tyari21 67:f141b2ad5fcd 17 // Setup the spi for 8 bit data, CPOL = 0, CPHA = 0
Tyari21 67:f141b2ad5fcd 18 // with a 10KHz clock rate
Tyari21 67:f141b2ad5fcd 19 spi.format(8,0);
Tyari21 67:f141b2ad5fcd 20 spi.frequency(10000);
Tyari21 67:f141b2ad5fcd 21 int data1, data2, mask, channel;
Tyari21 67:f141b2ad5fcd 22 // Supply voltage is nominally 3.3V
Tyari21 67:f141b2ad5fcd 23 float VCC=3.3, vIn;
Tyari21 67:f141b2ad5fcd 24 while(1) {
Tyari21 67:f141b2ad5fcd 25 for (channel = 0; channel<2; channel++){
Tyari21 67:f141b2ad5fcd 26 if(channel == 0){
Tyari21 67:f141b2ad5fcd 27 mask = MCP3002_CH0;
Tyari21 67:f141b2ad5fcd 28 }else{
Tyari21 67:f141b2ad5fcd 29 mask = MCP3002_CH1;
Tyari21 67:f141b2ad5fcd 30 }
Tyari21 67:f141b2ad5fcd 31 cs = 0;
Tyari21 67:f141b2ad5fcd 32 data1 = spi.write(mask);
Tyari21 67:f141b2ad5fcd 33 data2 = spi.write(0);
Tyari21 67:f141b2ad5fcd 34 cs = 1;
Tyari21 67:f141b2ad5fcd 35 // Format for MSB set
Tyari21 67:f141b2ad5fcd 36 data1 &= 0x03; // keep only three bits
Tyari21 67:f141b2ad5fcd 37 data2 |= data1 << 8 ; // shift and add to LSB
Tyari21 67:f141b2ad5fcd 38 // data2 ranges from 0 to 1023 for voltage from 0 to VCC
Tyari21 67:f141b2ad5fcd 39 vIn = VCC*data2/1000.;
Tyari21 67:f141b2ad5fcd 40 pc.printf("Channel %i Voltage is %f \r\n",channel,vIn);
Tyari21 67:f141b2ad5fcd 41 }
Tyari21 67:f141b2ad5fcd 42 wait(1);
Jonathan Austin 0:2757d7abb7d9 43 }
Jonathan Austin 0:2757d7abb7d9 44 }