Creates square-wave frequency output on pin p22. Custom frequency between 1Hz and 48 MHz. (LPC 1768)
Creates square-wave frequency output on pin22 with custom frequency.
Tested for frequencies from 1Hz to 48MHz. The accuracy depends heavily on the frequency - at 12, 24, 48 MHz the frequency deviation is less than 1%, but at 20 MHz it is about 20%.
Uses Library FastPWM ( http://mbed.org/users/Sissors/code/FastPWM/ ). For LPC 1768.
How to use this Library:
#include "mbed.h" #include "PwmOscillator.h" PwmOscillator oscillator; DigitalOut led1(LED1); int main() { oscillator.initWithFrequency(8000000); // initialize oscillator instance (pin p22) with custom frequency, here: 8MHz led1=1; // optional: indicator LED shows that oscillator is running oscillator.start(); // start oscillator wait(5); // optional: oscillator is running 5 seconds oscillator.stop(); // stop oscillator led1=0; }
PwmOscillator.h
- Committer:
- geotec
- Date:
- 2012-12-14
- Revision:
- 0:9e0f295a55a4
- Child:
- 1:4bbb380a1089
File content as of revision 0:9e0f295a55a4:
#include "mbed.h" /** Creates square-wave frequency output on pin22 with custom frequency. Tested for frequency range from 1Hz to 48MHz. * The accuracy is depends on the frequency - at 12, 24, 48 MHz the frequency deviation is less than 1% but at 20 MHz it is about 20%. * Uses Library FastPWM ( http://mbed.org/users/Sissors/code/FastPWM/ ). */ class PwmOscillator { public: /** Initialize PwmOscillator instance with frequency [Hz]. * @param frequencyHz = frequency in Hz (1 ... 48000000) */ void initWithFrequency(int frequencyHz); /** Start oscillator */ void start(); /** Stop oscillator */ void stop(); };