David Summers / Mbed 2 deprecated MS5611

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Dependencies:   mbed

main.cpp@2:b6a0d4ba24a1, 2018-03-15 (annotated)

Committer:
summers
Date:
Thu Mar 15 17:07:42 2018 +0000
Revision:
2:b6a0d4ba24a1
Parent:
1:3295382ddc81
Child:
3:a8c38c3fe967
First Draft of SPI interface to MS5611 pressure sensor

Who changed what in which revision?

UserRevisionLine numberNew contents of line
summers 0:9146d1e52be0 1 #include "mbed.h"
summers 1:3295382ddc81 2 #include "main.h"
summers 0:9146d1e52be0 3
summers 1:3295382ddc81 4 Serial pc(SERIAL_TX, SERIAL_RX, 115200); // tx, rx
summers 1:3295382ddc81 5 //DigitalOut led(LED_RED);
summers 1:3295382ddc81 6 //SPI spi(PTC6,PTC7,PTD1,PTC0);
summers 1:3295382ddc81 7 //SPI spi(PTC6,PTC7,PTD1); // my prefered, but mixed
summers 1:3295382ddc81 8 SPI spi(PTC6,PTC7,PTC5); // PTC5 - the LED
summers 1:3295382ddc81 9 //SPI spi(PTD2,PTD3,PTD1);
summers 1:3295382ddc81 10 DigitalOut cs(PTC0);
summers 0:9146d1e52be0 11
summers 0:9146d1e52be0 12 int main()
summers 0:9146d1e52be0 13 {
summers 1:3295382ddc81 14 int PROM[8];
summers 2:b6a0d4ba24a1 15 uint32_t D1,D2;
summers 2:b6a0d4ba24a1 16 double T,P;
summers 1:3295382ddc81 17 cs.write(1); // disable all SPI
summers 2:b6a0d4ba24a1 18 pc.printf("Hello World!\r\n");
summers 1:3295382ddc81 19 MS5611_init(PROM);
summers 1:3295382ddc81 20 for (int i=0; i<8; i++) {
summers 2:b6a0d4ba24a1 21 pc.printf("Prom(%i): %i\r\n",i,PROM[i]);
summers 1:3295382ddc81 22 }
summers 2:b6a0d4ba24a1 23 // the third paramater gives over samping
summers 2:b6a0d4ba24a1 24 // 0 - 256
summers 2:b6a0d4ba24a1 25 // 1 - 512
summers 2:b6a0d4ba24a1 26 // 2 - 1024
summers 2:b6a0d4ba24a1 27 // 3 - 2048
summers 2:b6a0d4ba24a1 28 // 4 - 4096
summers 2:b6a0d4ba24a1 29 MS5611(&D1,&D2,4);
summers 2:b6a0d4ba24a1 30 pc.printf("D1 = %i\r\nD2 = %i\r\n",D1,D2);
summers 2:b6a0d4ba24a1 31
summers 2:b6a0d4ba24a1 32 MS5611_phys(D1,D2,PROM,&T,&P);
summers 2:b6a0d4ba24a1 33
summers 2:b6a0d4ba24a1 34 pc.printf("Temperature = %f deg C\r\n",T/100.0);
summers 2:b6a0d4ba24a1 35 pc.printf("Pressure = %f mbar\r\n",P/100.0);
summers 2:b6a0d4ba24a1 36
summers 1:3295382ddc81 37 }
summers 1:3295382ddc81 38
summers 1:3295382ddc81 39 void MS5611_init(int *PROM)
summers 1:3295382ddc81 40 {
summers 2:b6a0d4ba24a1 41 long crc=0;
summers 1:3295382ddc81 42 spi.format(8,0); // 8 bit mode 0 - this is default anyway but good to code.
summers 1:3295382ddc81 43 spi.frequency(1000000); // 1MHz is this the minimum?
summers 1:3295382ddc81 44 cs.write(0); // Enable the MS5611 intercae
summers 2:b6a0d4ba24a1 45 if (spi.write(0x1E)!=0xfe) {
summers 2:b6a0d4ba24a1 46 pc.printf("Error reseting the device\r\n");
summers 2:b6a0d4ba24a1 47 }
summers 1:3295382ddc81 48 wait_ms(3); // give time for ROM to reload 2.8ms by the spec
summers 2:b6a0d4ba24a1 49 cs.write(1); // close the connection - does it finish the command?
summers 2:b6a0d4ba24a1 50 wait_us(10); // Pause after putting CSB high
summers 1:3295382ddc81 51 for (int i=0; i<8; i++) {
summers 2:b6a0d4ba24a1 52 cs.write(0); // enable the SC to start a command.
summers 2:b6a0d4ba24a1 53 if (spi.write(0xA0|(i<<1))!=0xfe) {
summers 2:b6a0d4ba24a1 54 pc.printf("Error reading prom(%i)\r\n",i);
summers 2:b6a0d4ba24a1 55 }
summers 1:3295382ddc81 56 register uint8_t promh=spi.write(0x00);
summers 1:3295382ddc81 57 register uint8_t proml=spi.write(0x00);
summers 2:b6a0d4ba24a1 58 cs.write(1); // disable CS to finish the command
summers 1:3295382ddc81 59 PROM[i]=((promh<<8)|(proml));
summers 2:b6a0d4ba24a1 60 crc|=(i==7)?(PROM[i]&0xff00):PROM[i];
summers 2:b6a0d4ba24a1 61 for (int j=0; j<16; j++) {
summers 2:b6a0d4ba24a1 62 crc=crc<<1;
summers 2:b6a0d4ba24a1 63 if (crc&0x1000000) { // implimt the CRC4 algorithm 0x13 -
summers 2:b6a0d4ba24a1 64 crc^=0x1300000; // to my mind this is implimented wrong - but its how the MS5611 does it
summers 2:b6a0d4ba24a1 65 }
summers 2:b6a0d4ba24a1 66 }
summers 2:b6a0d4ba24a1 67 wait_us(10); // Pause probably not stricly needed, but after switching CSB high give a bit of time.
summers 1:3295382ddc81 68 }
summers 2:b6a0d4ba24a1 69 if ((crc>>20)!=(PROM[7]&0xf))
summers 2:b6a0d4ba24a1 70 pc.printf("CRC check sum: %x vs recorded %x\r\n",crc>>20,PROM[7]&0xf);
summers 1:3295382ddc81 71 }
summers 1:3295382ddc81 72
summers 2:b6a0d4ba24a1 73 void MS5611(uint32_t *D1, uint32_t *D2, int os)
summers 1:3295382ddc81 74 {
summers 1:3295382ddc81 75 // cs.write(0);
summers 1:3295382ddc81 76 spi.format(8,0);
summers 1:3295382ddc81 77 spi.frequency(1000000);
summers 2:b6a0d4ba24a1 78 cs.write(0); // Enable the MS5611 intercae
summers 2:b6a0d4ba24a1 79 if (spi.write(0x1E)!=0xfe) { // and reset the device
summers 2:b6a0d4ba24a1 80 pc.printf("Error reseting the device\r\n");
summers 2:b6a0d4ba24a1 81 }
summers 2:b6a0d4ba24a1 82 wait_ms(3); // give time for ROM to reload 2.8ms by the spec
summers 2:b6a0d4ba24a1 83 cs.write(1); // close the connection - does it finish the command?
summers 2:b6a0d4ba24a1 84 wait_us(10); // Pause after putting CSB high
summers 2:b6a0d4ba24a1 85 cs.write(0); // Enable the MS5611 intercae
summers 2:b6a0d4ba24a1 86 if (spi.write(0x40|(os<<1))!=0xfe) { // D1 please
summers 2:b6a0d4ba24a1 87 pc.printf("Error asking for D1\r\n");
summers 2:b6a0d4ba24a1 88 }
summers 2:b6a0d4ba24a1 89 cs.write(1); // Disable the MS5611 intercae
summers 2:b6a0d4ba24a1 90 wait_us(600*(1<<os)); // pause for read, longer when oversampling
summers 2:b6a0d4ba24a1 91 cs.write(0); // Enable the MS5611 intercae
summers 2:b6a0d4ba24a1 92 register uint8_t d1h=spi.write(0x00);
summers 2:b6a0d4ba24a1 93 register uint8_t d1m=spi.write(0x00);
summers 2:b6a0d4ba24a1 94 register uint8_t d1l=spi.write(0x00);
summers 2:b6a0d4ba24a1 95 cs.write(1); // and terminate the command
summers 2:b6a0d4ba24a1 96 wait_us(10); // Pause after putting CSB high
summers 2:b6a0d4ba24a1 97 cs.write(0); // Enable the MS5611 intercae
summers 2:b6a0d4ba24a1 98 if (spi.write(0x50|(os<<1))!=0xfe) { // D2 please
summers 2:b6a0d4ba24a1 99 pc.printf("Error asking for D2\r\n");
summers 2:b6a0d4ba24a1 100 }
summers 2:b6a0d4ba24a1 101 cs.write(1); // Disable the MS5611 intercae
summers 2:b6a0d4ba24a1 102 wait_us(600*(1<<os)); // pause for read, longer when oversampling
summers 2:b6a0d4ba24a1 103 cs.write(0); // Enable the MS5611 intercae
summers 2:b6a0d4ba24a1 104 register uint8_t d2h=spi.write(0x00);
summers 2:b6a0d4ba24a1 105 register uint8_t d2m=spi.write(0x00);
summers 2:b6a0d4ba24a1 106 register uint8_t d2l=spi.write(0x00);
summers 2:b6a0d4ba24a1 107 cs.write(1); // and terminate the command
summers 2:b6a0d4ba24a1 108 *D1=((uint32_t) d1h<<16)|((uint32_t) d1m<<8)|((uint32_t) d1l);
summers 2:b6a0d4ba24a1 109 *D2=((uint32_t) d2h<<16)|((uint32_t) d2m<<8)|((uint32_t) d2l);
summers 2:b6a0d4ba24a1 110 }
summers 2:b6a0d4ba24a1 111
summers 2:b6a0d4ba24a1 112 void MS5611_phys(uint32_t D1,uint32_t D2, int *PROM, double *T, double *P)
summers 2:b6a0d4ba24a1 113 {
summers 2:b6a0d4ba24a1 114 int64_t dt=D2-(PROM[5]<<8);
summers 2:b6a0d4ba24a1 115 *T=2000.0+((double) dt*PROM[6])/8388608.0;
summers 2:b6a0d4ba24a1 116 int64_t off128=(PROM[2]<<23)+PROM[4]*dt;
summers 2:b6a0d4ba24a1 117 int64_t sens256=(PROM[1]<<23)+PROM[3]*dt;
summers 2:b6a0d4ba24a1 118 *P=(((double) D1*sens256)/536870912.0-((double) off128)/128.0)/ 4194304.0;
summers 0:9146d1e52be0 119 }