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LAB 3 DAC
Fork of DACandticker_sample by
name.cpp
- Committer:
- Bossman
- Date:
- 2018-02-15
- Revision:
- 4:dc6e0fdcf6b4
File content as of revision 4:dc6e0fdcf6b4:
// Revised for mbed 5 #include "mbed.h" #include "sineTable.h" Ticker tickout ; // Creates periodic interrupt AnalogOut ao(PTE30) ; // Analog output Ticker tick; // Ticker for reading analog AnalogIn ain(A0) ; // Analog input DigitalOut led1(LED_RED); 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) ; } volatile int index = 0 ; // index into array of sin values void writeAout() { ao.write_u16(sine[index]) ; index = (index + 1) % 64 ; } // Main program // Initialise variables // Attach ISR for ticker // Procss messages from mailbox int main() { int update_us = 1000 ; int volts = 0; led1 = 1 ; // turn off // 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 update_us = 1000000/((1+(49*volts/330))*64) ; tickout.detach() ; tickout.attach_us(callback(&writeAout), update_us); } } }