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Lab 3 ADC
Fork of ADCandticker_sample by
main.cpp
- Committer:
- WilliamMarshQMUL
- Date:
- 2017-01-31
- Revision:
- 0:ad3cdc525b99
- Child:
- 1:126dd2f5fc2d
File content as of revision 0:ad3cdc525b99:
// LAB 3 SAMPLE PROGRAM 1 #include "mbed.h" #include "rtos.h" Ticker tick; // Ticker for reading analog AnalogIn ain(A0) ; // Analog input DigitalOut led1(LED_RED); // Red LED Serial pc(USBTX, USBRX); // tx, rx, for debugging // Message type typedef struct { uint16_t analog; /* Analog input value */ } message_t; // Mail box Mail<message_t, 2> mailbox; // Function called every 10ms to read ADC // Low pass filter // Every 10th value is sent to mailbox volatile int samples = 0 ; volatile uint16_t smoothed = 0 ; void readA0() { smoothed = (smoothed >> 1) + (ain.read_u16() >> 1) ; samples++ ; if (samples == 10) { // send to thread message_t *mess = mailbox.alloc() ; // may fail but does not block if (mess) { mess->analog = smoothed ; mailbox.put(mess); // fails but does not block if full } samples = 0; } } // Write voltage digits // v Voltage as scale int, e.g. 3.30 is 330 void vToString(int v, char* s) { s[3] = '0' + (v % 10) ; v = v / 10 ; s[2] = '0' + (v % 10) ; v = v / 10 ; s[0] = '0' + (v % 10) ; } // Main program // Initialise variables // Attach ISR for ticker // Procss messages from mailbox int main() { led1 = 1 ; // turn off int volts = 0 ; const int threshold = 100 ; int counter = 0 ; char vstring[] = "X.XX\r\n" ; tick.attach_us(callback(&readA0), 10000); // ticks every 10ms while (true) { osEvent evt = mailbox.get(); // wait for mail if (evt.status == osEventMail) { message_t* mess = (message_t*)evt.value.p ; volts = (mess->analog * 330) / 0xffff ; mailbox.free(mess) ; // free the message space if (volts > threshold) led1 = 0 ; else led1 = 1 ; vToString(volts, vstring) ; counter++ ; if (counter == 10) { // limit bandwidth of serial pc.printf(vstring) ; counter = 0 ; } } } }