Natalia Govor / Mbed OS lab3_ADC

Analog to digital conversion. Reads voltage and prints it in the terminal. Switches on/off the leads depending on the voltage threashold. Uses button for voltage callibration.

Fork of ADCandticker_sample by William Marsh

main.cpp@2:26893e7c0068, 2018-02-09 (annotated)

Committer:
natgovor
Date:
Fri Feb 09 16:31:44 2018 +0000
Revision:
2:26893e7c0068
Parent:
1:126dd2f5fc2d 
Analog to digital conversion. Reads voltage and displays it in the terminal.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
WilliamMarshQMUL 0:ad3cdc525b99 1
WilliamMarshQMUL 0:ad3cdc525b99 2 // LAB 3 SAMPLE PROGRAM 1
WilliamMarshQMUL 1:126dd2f5fc2d 3 // Revised for mbed 5
WilliamMarshQMUL 0:ad3cdc525b99 4
WilliamMarshQMUL 0:ad3cdc525b99 5 #include "mbed.h"
WilliamMarshQMUL 1:126dd2f5fc2d 6
WilliamMarshQMUL 0:ad3cdc525b99 7
WilliamMarshQMUL 0:ad3cdc525b99 8 Ticker tick; // Ticker for reading analog
WilliamMarshQMUL 0:ad3cdc525b99 9 AnalogIn ain(A0) ; // Analog input
natgovor 2:26893e7c0068 10
natgovor 2:26893e7c0068 11 const int states_number = 6; // number of leds + 1
natgovor 2:26893e7c0068 12 DigitalOut leds[5] = { PTA13, PTD5, PTD0, PTD2, PTD3 };
natgovor 2:26893e7c0068 13
natgovor 2:26893e7c0068 14 // button setup
natgovor 2:26893e7c0068 15 DigitalIn button(PTE1, PullUp);
natgovor 2:26893e7c0068 16 enum buttonPos { up, down, bounce }; // Button positions
natgovor 2:26893e7c0068 17 buttonPos pos = up ;
natgovor 2:26893e7c0068 18 int bcounter = 0 ;
WilliamMarshQMUL 0:ad3cdc525b99 19
WilliamMarshQMUL 0:ad3cdc525b99 20 Serial pc(USBTX, USBRX); // tx, rx, for debugging
WilliamMarshQMUL 0:ad3cdc525b99 21
WilliamMarshQMUL 0:ad3cdc525b99 22 // Message type
WilliamMarshQMUL 0:ad3cdc525b99 23 typedef struct {
WilliamMarshQMUL 0:ad3cdc525b99 24 uint16_t analog; /* Analog input value */
natgovor 2:26893e7c0068 25 bool buttonPressed;
WilliamMarshQMUL 0:ad3cdc525b99 26 } message_t;
WilliamMarshQMUL 0:ad3cdc525b99 27
WilliamMarshQMUL 0:ad3cdc525b99 28 // Mail box
WilliamMarshQMUL 0:ad3cdc525b99 29 Mail<message_t, 2> mailbox;
WilliamMarshQMUL 0:ad3cdc525b99 30
WilliamMarshQMUL 0:ad3cdc525b99 31 // Function called every 10ms to read ADC
WilliamMarshQMUL 0:ad3cdc525b99 32 // Low pass filter
WilliamMarshQMUL 0:ad3cdc525b99 33 // Every 10th value is sent to mailbox
WilliamMarshQMUL 0:ad3cdc525b99 34 volatile int samples = 0 ;
WilliamMarshQMUL 0:ad3cdc525b99 35 volatile uint16_t smoothed = 0 ;
natgovor 2:26893e7c0068 36 volatile bool pressEvent = false;
WilliamMarshQMUL 0:ad3cdc525b99 37 void readA0() {
natgovor 2:26893e7c0068 38 // Check button state
natgovor 2:26893e7c0068 39 switch (pos) {
natgovor 2:26893e7c0068 40 case up :
natgovor 2:26893e7c0068 41 if (!button.read()) { // now down
natgovor 2:26893e7c0068 42 pressEvent = true;
natgovor 2:26893e7c0068 43 pos = down ;
natgovor 2:26893e7c0068 44 }
natgovor 2:26893e7c0068 45 break ;
natgovor 2:26893e7c0068 46 case down :
natgovor 2:26893e7c0068 47 if (button == 1) { // no longer down
natgovor 2:26893e7c0068 48 bcounter = 3 ; // wait four cycles
natgovor 2:26893e7c0068 49 pos = bounce ;
natgovor 2:26893e7c0068 50 }
natgovor 2:26893e7c0068 51 break ;
natgovor 2:26893e7c0068 52 case bounce :
natgovor 2:26893e7c0068 53 if (button == 0) { // down again - button has bounced
natgovor 2:26893e7c0068 54 pos = down ; // no event
natgovor 2:26893e7c0068 55 } else if (bcounter == 0) {
natgovor 2:26893e7c0068 56 pos = up ; // delay passed - reset to up
natgovor 2:26893e7c0068 57 } else {
natgovor 2:26893e7c0068 58 bcounter-- ; // continue waiting
natgovor 2:26893e7c0068 59 }
natgovor 2:26893e7c0068 60 break ;
natgovor 2:26893e7c0068 61 }
natgovor 2:26893e7c0068 62
WilliamMarshQMUL 0:ad3cdc525b99 63 smoothed = (smoothed >> 1) + (ain.read_u16() >> 1) ;
WilliamMarshQMUL 0:ad3cdc525b99 64 samples++ ;
WilliamMarshQMUL 0:ad3cdc525b99 65 if (samples == 10) {
WilliamMarshQMUL 0:ad3cdc525b99 66 // send to thread
WilliamMarshQMUL 0:ad3cdc525b99 67 message_t *mess = mailbox.alloc() ; // may fail but does not block
WilliamMarshQMUL 0:ad3cdc525b99 68 if (mess) {
WilliamMarshQMUL 0:ad3cdc525b99 69 mess->analog = smoothed ;
natgovor 2:26893e7c0068 70 mess->buttonPressed = pressEvent;
WilliamMarshQMUL 0:ad3cdc525b99 71 mailbox.put(mess); // fails but does not block if full
WilliamMarshQMUL 0:ad3cdc525b99 72 }
WilliamMarshQMUL 0:ad3cdc525b99 73 samples = 0;
natgovor 2:26893e7c0068 74 pressEvent = false;
WilliamMarshQMUL 0:ad3cdc525b99 75 }
WilliamMarshQMUL 0:ad3cdc525b99 76 }
WilliamMarshQMUL 0:ad3cdc525b99 77
WilliamMarshQMUL 0:ad3cdc525b99 78 // Write voltage digits
WilliamMarshQMUL 0:ad3cdc525b99 79 // v Voltage as scale int, e.g. 3.30 is 330
WilliamMarshQMUL 0:ad3cdc525b99 80 void vToString(int v, char* s) {
WilliamMarshQMUL 0:ad3cdc525b99 81 s[3] = '0' + (v % 10) ;
WilliamMarshQMUL 0:ad3cdc525b99 82 v = v / 10 ;
WilliamMarshQMUL 0:ad3cdc525b99 83 s[2] = '0' + (v % 10) ;
WilliamMarshQMUL 0:ad3cdc525b99 84 v = v / 10 ;
WilliamMarshQMUL 0:ad3cdc525b99 85 s[0] = '0' + (v % 10) ;
WilliamMarshQMUL 0:ad3cdc525b99 86 }
WilliamMarshQMUL 0:ad3cdc525b99 87
natgovor 2:26893e7c0068 88 void lightLeds(int threshold_index) {
natgovor 2:26893e7c0068 89 int leds_number = states_number - 1;
natgovor 2:26893e7c0068 90 for (int i=0; i<leds_number; i++) {
natgovor 2:26893e7c0068 91 if (i <= threshold_index - 1) {
natgovor 2:26893e7c0068 92 leds[i] = 1;
natgovor 2:26893e7c0068 93 } else {
natgovor 2:26893e7c0068 94 leds[i] = 0;
natgovor 2:26893e7c0068 95 }
natgovor 2:26893e7c0068 96 }
natgovor 2:26893e7c0068 97 }
natgovor 2:26893e7c0068 98
natgovor 2:26893e7c0068 99 void calculate_thresholds(int max_voltage, int* threshold) {
natgovor 2:26893e7c0068 100 int interval = max_voltage / states_number;
natgovor 2:26893e7c0068 101 for (int i = 0; i < states_number; i++) {
natgovor 2:26893e7c0068 102 if (i == 0) {
natgovor 2:26893e7c0068 103 threshold[i] = interval;
natgovor 2:26893e7c0068 104 } else {
natgovor 2:26893e7c0068 105 threshold[i] = threshold[i-1] + interval;
natgovor 2:26893e7c0068 106 }
natgovor 2:26893e7c0068 107 }
natgovor 2:26893e7c0068 108 }
natgovor 2:26893e7c0068 109
WilliamMarshQMUL 0:ad3cdc525b99 110 // Main program
WilliamMarshQMUL 0:ad3cdc525b99 111 // Initialise variables
WilliamMarshQMUL 0:ad3cdc525b99 112 // Attach ISR for ticker
WilliamMarshQMUL 0:ad3cdc525b99 113 // Procss messages from mailbox
WilliamMarshQMUL 0:ad3cdc525b99 114 int main() {
WilliamMarshQMUL 0:ad3cdc525b99 115 int volts = 0 ;
WilliamMarshQMUL 0:ad3cdc525b99 116 int counter = 0 ;
WilliamMarshQMUL 0:ad3cdc525b99 117 char vstring[] = "X.XX\r\n" ;
natgovor 2:26893e7c0068 118
natgovor 2:26893e7c0068 119 //int max_voltage = 330;
natgovor 2:26893e7c0068 120 int threshold[states_number];
natgovor 2:26893e7c0068 121
natgovor 2:26893e7c0068 122 calculate_thresholds(330, threshold);
WilliamMarshQMUL 0:ad3cdc525b99 123
WilliamMarshQMUL 0:ad3cdc525b99 124 tick.attach_us(callback(&readA0), 10000); // ticks every 10ms
WilliamMarshQMUL 0:ad3cdc525b99 125 while (true) {
WilliamMarshQMUL 0:ad3cdc525b99 126 osEvent evt = mailbox.get(); // wait for mail
WilliamMarshQMUL 0:ad3cdc525b99 127 if (evt.status == osEventMail) {
WilliamMarshQMUL 0:ad3cdc525b99 128 message_t* mess = (message_t*)evt.value.p ;
natgovor 2:26893e7c0068 129 bool pressEvent = mess->buttonPressed;
natgovor 2:26893e7c0068 130 if (pressEvent) {
natgovor 2:26893e7c0068 131 // recalculate treshold
natgovor 2:26893e7c0068 132 calculate_thresholds(volts, threshold);
natgovor 2:26893e7c0068 133 }
WilliamMarshQMUL 0:ad3cdc525b99 134 volts = (mess->analog * 330) / 0xffff ;
WilliamMarshQMUL 0:ad3cdc525b99 135 mailbox.free(mess) ; // free the message space
natgovor 2:26893e7c0068 136
natgovor 2:26893e7c0068 137 if (volts < threshold[0]) {
natgovor 2:26893e7c0068 138 lightLeds(0);
natgovor 2:26893e7c0068 139 } else if (volts > threshold[0] && volts < threshold[1]) {
natgovor 2:26893e7c0068 140 lightLeds(1);
natgovor 2:26893e7c0068 141 } else if (volts > threshold[1] && volts < threshold[2]) {
natgovor 2:26893e7c0068 142 lightLeds(2);
natgovor 2:26893e7c0068 143 } else if (volts > threshold[2] && volts < threshold[3]) {
natgovor 2:26893e7c0068 144 lightLeds(3);
natgovor 2:26893e7c0068 145 } else if (volts > threshold[3] && volts < threshold[4]) {
natgovor 2:26893e7c0068 146 lightLeds(4);
natgovor 2:26893e7c0068 147 } else if (volts > threshold[4]) {
natgovor 2:26893e7c0068 148 lightLeds(5);
natgovor 2:26893e7c0068 149 }
natgovor 2:26893e7c0068 150
WilliamMarshQMUL 0:ad3cdc525b99 151 vToString(volts, vstring) ;
WilliamMarshQMUL 0:ad3cdc525b99 152 counter++ ;
WilliamMarshQMUL 0:ad3cdc525b99 153 if (counter == 10) { // limit bandwidth of serial
WilliamMarshQMUL 0:ad3cdc525b99 154 pc.printf(vstring) ;
WilliamMarshQMUL 0:ad3cdc525b99 155 counter = 0 ;
WilliamMarshQMUL 0:ad3cdc525b99 156 }
WilliamMarshQMUL 0:ad3cdc525b99 157 }
WilliamMarshQMUL 0:ad3cdc525b99 158
WilliamMarshQMUL 0:ad3cdc525b99 159 }
WilliamMarshQMUL 0:ad3cdc525b99 160 }