Andreas Steffen / Mbed 2 deprecated PIservo

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Dependencies:   mbed

main.cpp@3:1a4ad4c82046, 2012-08-07 (annotated)

Committer:
Reignbow
Date:
Tue Aug 07 13:41:11 2012 +0000
Revision:
3:1a4ad4c82046
Parent:
2:6d472c554758
Child:
4:c38f7e4e8fda
SPI reads over registers (faster). All calculations as int.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Reignbow 0:3e6ae21a6bb1 1 /* PIservo
Reignbow 0:3e6ae21a6bb1 2 implement a PI controller with USB serial gain setting to stabilize dipole trap power.
Reignbow 0:3e6ae21a6bb1 3 Two analog inputs (control and sensor), one analog output (to RF VCA).
Reignbow 0:3e6ae21a6bb1 4
Reignbow 0:3e6ae21a6bb1 5 20120806 Andreas Steffen
Reignbow 0:3e6ae21a6bb1 6 */
Reignbow 0:3e6ae21a6bb1 7
Reignbow 0:3e6ae21a6bb1 8
Reignbow 0:3e6ae21a6bb1 9 #include "mbed.h"
Reignbow 0:3e6ae21a6bb1 10
Reignbow 1:dc799997391e 11 DigitalOut adcCS(p8);
Reignbow 2:6d472c554758 12 DigitalOut cyc(p10);
Reignbow 0:3e6ae21a6bb1 13 AnalogOut vca(p18);
Reignbow 3:1a4ad4c82046 14 SPI adc(p5,p6,p7); //talk to ad7921
Reignbow 0:3e6ae21a6bb1 15 Serial pc(USBTX, USBRX);
Reignbow 0:3e6ae21a6bb1 16
Reignbow 0:3e6ae21a6bb1 17
Reignbow 0:3e6ae21a6bb1 18 Timer t;
Reignbow 0:3e6ae21a6bb1 19 Ticker commTick;
Reignbow 0:3e6ae21a6bb1 20 Ticker intTick;
Reignbow 0:3e6ae21a6bb1 21
Reignbow 3:1a4ad4c82046 22 int pGain = 1;
Reignbow 3:1a4ad4c82046 23 int iGain = 100;
Reignbow 3:1a4ad4c82046 24 int integrator = 0; //the building up integrator value
Reignbow 0:3e6ae21a6bb1 25
Reignbow 0:3e6ae21a6bb1 26 void serialComm(){
Reignbow 0:3e6ae21a6bb1 27 char c;
Reignbow 3:1a4ad4c82046 28 int i;
Reignbow 0:3e6ae21a6bb1 29
Reignbow 0:3e6ae21a6bb1 30 if (pc.readable()) {
Reignbow 0:3e6ae21a6bb1 31 c = pc.getc();
Reignbow 3:1a4ad4c82046 32 pc.scanf("%i", &i);
Reignbow 0:3e6ae21a6bb1 33 switch (c) {
Reignbow 0:3e6ae21a6bb1 34 case 'p':
Reignbow 3:1a4ad4c82046 35 pGain = i;
Reignbow 3:1a4ad4c82046 36 pc.printf("Changed p gain to %i.\n",pGain);
Reignbow 0:3e6ae21a6bb1 37 break;
Reignbow 0:3e6ae21a6bb1 38 case 'i':
Reignbow 3:1a4ad4c82046 39 iGain = i;
Reignbow 3:1a4ad4c82046 40 pc.printf("Changed i gain to %i.\n",iGain);
Reignbow 3:1a4ad4c82046 41 if (i==0)
Reignbow 3:1a4ad4c82046 42 integrator = 0;
Reignbow 0:3e6ae21a6bb1 43 break;
Reignbow 0:3e6ae21a6bb1 44 default:
Reignbow 0:3e6ae21a6bb1 45 pc.printf("Command not understood.\n",iGain);
Reignbow 3:1a4ad4c82046 46 pc.printf("Read %c and %i.\n",c,i);
Reignbow 0:3e6ae21a6bb1 47 break;
Reignbow 0:3e6ae21a6bb1 48 }
Reignbow 0:3e6ae21a6bb1 49 }
Reignbow 0:3e6ae21a6bb1 50 }
Reignbow 0:3e6ae21a6bb1 51
Reignbow 0:3e6ae21a6bb1 52
Reignbow 0:3e6ae21a6bb1 53 int main() {
Reignbow 1:dc799997391e 54 int ctl=0;
Reignbow 3:1a4ad4c82046 55 int pd=0;
Reignbow 3:1a4ad4c82046 56 int err=0;
Reignbow 0:3e6ae21a6bb1 57 pc.printf("mbed restarted!\n");
Reignbow 0:3e6ae21a6bb1 58
Reignbow 3:1a4ad4c82046 59 adc.format(16,2);
Reignbow 3:1a4ad4c82046 60 adc.frequency(5000000);
Reignbow 1:dc799997391e 61
Reignbow 3:1a4ad4c82046 62 commTick.attach(&serialComm,0.5); //check serial every half second
Reignbow 2:6d472c554758 63 cyc = 0;
Reignbow 0:3e6ae21a6bb1 64
Reignbow 0:3e6ae21a6bb1 65 while(1) {
Reignbow 3:1a4ad4c82046 66 cyc = cyc^1; //toggle debug pin
Reignbow 2:6d472c554758 67
Reignbow 3:1a4ad4c82046 68 //stagger read and output
Reignbow 3:1a4ad4c82046 69 //The SPI read takes a long time, so start it by writing to the data
Reignbow 3:1a4ad4c82046 70 //register, do sth. else (create new output), then get the value
Reignbow 3:1a4ad4c82046 71 //and start the read from the other channel
Reignbow 3:1a4ad4c82046 72
Reignbow 3:1a4ad4c82046 73 //begin SPI transfer
Reignbow 1:dc799997391e 74 adcCS = 0;
Reignbow 3:1a4ad4c82046 75 LPC_SSP1->DR = 3<<13; //initialize SSP1 transfer by writing to data register; select ch 1
Reignbow 3:1a4ad4c82046 76
Reignbow 3:1a4ad4c82046 77 err = ctl - pd; //convert to volt
Reignbow 3:1a4ad4c82046 78 integrator += err*iGain;
Reignbow 3:1a4ad4c82046 79 t.reset(); //reset timer to get next integration time
Reignbow 3:1a4ad4c82046 80 vca.write_u16( (err * pGain + integrator)>>10 ); //analog output
Reignbow 3:1a4ad4c82046 81
Reignbow 3:1a4ad4c82046 82 //read SPI transfer results
Reignbow 3:1a4ad4c82046 83 while(!(LPC_SSP1->SR & 0x04)) {}
Reignbow 3:1a4ad4c82046 84 pd = LPC_SSP1->DR & 0xFFF; //last 12 bits are data
Reignbow 3:1a4ad4c82046 85 adcCS = 1;
Reignbow 1:dc799997391e 86
Reignbow 3:1a4ad4c82046 87 //begin transfer from other channel
Reignbow 3:1a4ad4c82046 88 adcCS = 0;
Reignbow 3:1a4ad4c82046 89 LPC_SSP1->DR = 1; //initialize SSP1 transfer by writing to data register; select ch 0
Reignbow 3:1a4ad4c82046 90
Reignbow 3:1a4ad4c82046 91 err = ctl-pd; //convert to volt
Reignbow 3:1a4ad4c82046 92 integrator += err*iGain;
Reignbow 3:1a4ad4c82046 93 vca.write_u16( (err * pGain + integrator)>>10 ); //analog output
Reignbow 3:1a4ad4c82046 94
Reignbow 3:1a4ad4c82046 95 //read SPI transfer results
Reignbow 3:1a4ad4c82046 96 while(!(LPC_SSP1->SR & 0x04)) {}
Reignbow 3:1a4ad4c82046 97 ctl = LPC_SSP1->DR & 0xFFF; //last 12 bits are data
Reignbow 3:1a4ad4c82046 98 adcCS = 1;
Reignbow 3:1a4ad4c82046 99
Reignbow 3:1a4ad4c82046 100 //pc.printf("Measuring ctl=%i and pd=%i, err=%i, integrator= %i\n",ctl,pd,err,integrator);
Reignbow 2:6d472c554758 101
Reignbow 0:3e6ae21a6bb1 102 }
Reignbow 0:3e6ae21a6bb1 103 }