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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
main.cpp@0:ad3cdc525b99, 2017-01-31 (annotated)
- Committer:
- WilliamMarshQMUL
- Date:
- Tue Jan 31 23:02:02 2017 +0000
- Revision:
- 0:ad3cdc525b99
- Child:
- 1:126dd2f5fc2d
First complete version
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
WilliamMarshQMUL | 0:ad3cdc525b99 | 1 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 2 | // LAB 3 SAMPLE PROGRAM 1 |
WilliamMarshQMUL | 0:ad3cdc525b99 | 3 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 4 | #include "mbed.h" |
WilliamMarshQMUL | 0:ad3cdc525b99 | 5 | #include "rtos.h" |
WilliamMarshQMUL | 0:ad3cdc525b99 | 6 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 7 | Ticker tick; // Ticker for reading analog |
WilliamMarshQMUL | 0:ad3cdc525b99 | 8 | AnalogIn ain(A0) ; // Analog input |
WilliamMarshQMUL | 0:ad3cdc525b99 | 9 | DigitalOut led1(LED_RED); // Red LED |
WilliamMarshQMUL | 0:ad3cdc525b99 | 10 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 11 | Serial pc(USBTX, USBRX); // tx, rx, for debugging |
WilliamMarshQMUL | 0:ad3cdc525b99 | 12 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 13 | // Message type |
WilliamMarshQMUL | 0:ad3cdc525b99 | 14 | typedef struct { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 15 | uint16_t analog; /* Analog input value */ |
WilliamMarshQMUL | 0:ad3cdc525b99 | 16 | } message_t; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 17 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 18 | // Mail box |
WilliamMarshQMUL | 0:ad3cdc525b99 | 19 | Mail<message_t, 2> mailbox; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 20 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 21 | // Function called every 10ms to read ADC |
WilliamMarshQMUL | 0:ad3cdc525b99 | 22 | // Low pass filter |
WilliamMarshQMUL | 0:ad3cdc525b99 | 23 | // Every 10th value is sent to mailbox |
WilliamMarshQMUL | 0:ad3cdc525b99 | 24 | volatile int samples = 0 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 25 | volatile uint16_t smoothed = 0 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 26 | void readA0() { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 27 | smoothed = (smoothed >> 1) + (ain.read_u16() >> 1) ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 28 | samples++ ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 29 | if (samples == 10) { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 30 | // send to thread |
WilliamMarshQMUL | 0:ad3cdc525b99 | 31 | message_t *mess = mailbox.alloc() ; // may fail but does not block |
WilliamMarshQMUL | 0:ad3cdc525b99 | 32 | if (mess) { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 33 | mess->analog = smoothed ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 34 | mailbox.put(mess); // fails but does not block if full |
WilliamMarshQMUL | 0:ad3cdc525b99 | 35 | } |
WilliamMarshQMUL | 0:ad3cdc525b99 | 36 | samples = 0; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 37 | } |
WilliamMarshQMUL | 0:ad3cdc525b99 | 38 | } |
WilliamMarshQMUL | 0:ad3cdc525b99 | 39 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 40 | // Write voltage digits |
WilliamMarshQMUL | 0:ad3cdc525b99 | 41 | // v Voltage as scale int, e.g. 3.30 is 330 |
WilliamMarshQMUL | 0:ad3cdc525b99 | 42 | void vToString(int v, char* s) { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 43 | s[3] = '0' + (v % 10) ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 44 | v = v / 10 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 45 | s[2] = '0' + (v % 10) ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 46 | v = v / 10 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 47 | s[0] = '0' + (v % 10) ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 48 | } |
WilliamMarshQMUL | 0:ad3cdc525b99 | 49 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 50 | // Main program |
WilliamMarshQMUL | 0:ad3cdc525b99 | 51 | // Initialise variables |
WilliamMarshQMUL | 0:ad3cdc525b99 | 52 | // Attach ISR for ticker |
WilliamMarshQMUL | 0:ad3cdc525b99 | 53 | // Procss messages from mailbox |
WilliamMarshQMUL | 0:ad3cdc525b99 | 54 | int main() { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 55 | led1 = 1 ; // turn off |
WilliamMarshQMUL | 0:ad3cdc525b99 | 56 | int volts = 0 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 57 | const int threshold = 100 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 58 | int counter = 0 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 59 | char vstring[] = "X.XX\r\n" ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 60 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 61 | tick.attach_us(callback(&readA0), 10000); // ticks every 10ms |
WilliamMarshQMUL | 0:ad3cdc525b99 | 62 | while (true) { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 63 | osEvent evt = mailbox.get(); // wait for mail |
WilliamMarshQMUL | 0:ad3cdc525b99 | 64 | if (evt.status == osEventMail) { |
WilliamMarshQMUL | 0:ad3cdc525b99 | 65 | message_t* mess = (message_t*)evt.value.p ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 66 | volts = (mess->analog * 330) / 0xffff ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 67 | mailbox.free(mess) ; // free the message space |
WilliamMarshQMUL | 0:ad3cdc525b99 | 68 | if (volts > threshold) led1 = 0 ; else led1 = 1 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 69 | vToString(volts, vstring) ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 70 | counter++ ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 71 | if (counter == 10) { // limit bandwidth of serial |
WilliamMarshQMUL | 0:ad3cdc525b99 | 72 | pc.printf(vstring) ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 73 | counter = 0 ; |
WilliamMarshQMUL | 0:ad3cdc525b99 | 74 | } |
WilliamMarshQMUL | 0:ad3cdc525b99 | 75 | } |
WilliamMarshQMUL | 0:ad3cdc525b99 | 76 | |
WilliamMarshQMUL | 0:ad3cdc525b99 | 77 | } |
WilliamMarshQMUL | 0:ad3cdc525b99 | 78 | } |