Rob Toulson / Mbed 2 deprecated PE_14-05_ADCInput

by Rob Toulson and Tim Wilmshurst from textbook "Fast and Effective Embedded Systems Design: Applying the ARM mbed"

Dependencies:   mbed

main.cpp@0:dd98f6992fa6, 2013-06-16 (annotated)

Committer:
robt
Date:
Sun Jun 16 15:42:09 2013 +0000
Revision:
0:dd98f6992fa6
by Rob Toulson and Tim Wilmshurst from textbook "Fast and Effective Embedded Systems Design: Applying the ARM mbed"

Who changed what in which revision?

UserRevisionLine numberNew contents of line
robt 0:dd98f6992fa6 1 /* Program Example 14.5: A bar graph meter for ADC input, using control registers to set up ADC and digital I/O
robt 0:dd98f6992fa6 2 */
robt 0:dd98f6992fa6 3 // variable declarations
robt 0:dd98f6992fa6 4 char ADC_channel=1; // ADC channel 1
robt 0:dd98f6992fa6 5 int ADCdata; //this will hold the result of the conversion
robt 0:dd98f6992fa6 6 int DigOutData=0; //a buffer for the output display pattern
robt 0:dd98f6992fa6 7
robt 0:dd98f6992fa6 8 // function prototype
robt 0:dd98f6992fa6 9 void delay(void);
robt 0:dd98f6992fa6 10
robt 0:dd98f6992fa6 11 //define addresses of control registers, as pointers to volatile data
robt 0:dd98f6992fa6 12 //(i.e. the memory contents)
robt 0:dd98f6992fa6 13 #define PINSEL1 (*(volatile unsigned long *)(0x4002C004))
robt 0:dd98f6992fa6 14 #define PCONP (*(volatile unsigned long *)(0x400FC0C4))
robt 0:dd98f6992fa6 15 #define AD0CR (*(volatile unsigned long *)(0x40034000))
robt 0:dd98f6992fa6 16 #define AD0GDR (*(volatile unsigned long *)(0x40034004))
robt 0:dd98f6992fa6 17 #define FIO2DIR0 (*(volatile unsigned char *)( 0x2009C040))
robt 0:dd98f6992fa6 18 #define FIO2PIN0 (*(volatile unsigned char *)( 0x2009C054))
robt 0:dd98f6992fa6 19
robt 0:dd98f6992fa6 20 int main() {
robt 0:dd98f6992fa6 21 FIO2DIR0=0xFF;// set lower byte of Port 2 to output, this drives bar graph
robt 0:dd98f6992fa6 22
robt 0:dd98f6992fa6 23 //initialise the ADC
robt 0:dd98f6992fa6 24 PINSEL1=0x00010000; //set bits 17-16 to 01 to enable AD0.1 (mbed pin 16)
robt 0:dd98f6992fa6 25 PCONP |= (1 << 12); // enable ADC clock
robt 0:dd98f6992fa6 26 AD0CR = (1 << ADC_channel) // select channel 1
robt 0:dd98f6992fa6 27 | (4 << 8) // Divide incoming clock by (4+1), giving 4.8MHz
robt 0:dd98f6992fa6 28 | (0 << 16) // BURST = 0, conversions under software control
robt 0:dd98f6992fa6 29 | (1 << 21) // PDN = 1, enables power
robt 0:dd98f6992fa6 30 | (1 << 24); // START = 1, start A/D conversion now
robt 0:dd98f6992fa6 31
robt 0:dd98f6992fa6 32 while(1) { // infinite loop
robt 0:dd98f6992fa6 33 AD0CR = AD0CR | 0x01000000; //start conversion by setting bit 24 to 1,
robt 0:dd98f6992fa6 34 //by ORing
robt 0:dd98f6992fa6 35 // wait for it to finish by polling the ADC DONE bit
robt 0:dd98f6992fa6 36 while ((AD0GDR & 0x80000000) == 0) { //test DONE bit, wait till it’s 1
robt 0:dd98f6992fa6 37 }
robt 0:dd98f6992fa6 38 ADCdata = AD0GDR; // get the data from AD0GDR
robt 0:dd98f6992fa6 39 AD0CR &= 0xF8FFFFFF; //stop ADC by setting START bits to zero
robt 0:dd98f6992fa6 40 // Shift data 4 bits to right justify, and 2 more to give 10-bit ADC
robt 0:dd98f6992fa6 41 // value - this gives convenient range of just over one thousand.
robt 0:dd98f6992fa6 42 ADCdata=(ADCdata>>6)&0x03FF; //and mask
robt 0:dd98f6992fa6 43 DigOutData=0x00; //clear the output buffer
robt 0:dd98f6992fa6 44 //display the data
robt 0:dd98f6992fa6 45 if (ADCdata>200)
robt 0:dd98f6992fa6 46 DigOutData=(DigOutData|0x01); //set the lsb by ORing with 1
robt 0:dd98f6992fa6 47 if (ADCdata>400)
robt 0:dd98f6992fa6 48 DigOutData=(DigOutData|0x02); //set the next lsb by ORing with 1
robt 0:dd98f6992fa6 49 if (ADCdata>600)
robt 0:dd98f6992fa6 50 DigOutData=(DigOutData|0x04);
robt 0:dd98f6992fa6 51 if (ADCdata>800)
robt 0:dd98f6992fa6 52 DigOutData=(DigOutData|0x08);
robt 0:dd98f6992fa6 53 if (ADCdata>1000)
robt 0:dd98f6992fa6 54 DigOutData=(DigOutData|0x10);
robt 0:dd98f6992fa6 55
robt 0:dd98f6992fa6 56 FIO2PIN0 = DigOutData; // set port 2 to Digoutdata
robt 0:dd98f6992fa6 57 delay(); // pause
robt 0:dd98f6992fa6 58 }
robt 0:dd98f6992fa6 59 }
robt 0:dd98f6992fa6 60
robt 0:dd98f6992fa6 61 void delay(void){ //delay function.
robt 0:dd98f6992fa6 62 int j; //loop variable j
robt 0:dd98f6992fa6 63 for (j=0; j<1000000; j++) {
robt 0:dd98f6992fa6 64 j++;
robt 0:dd98f6992fa6 65 j--; //waste time
robt 0:dd98f6992fa6 66 }
robt 0:dd98f6992fa6 67 }