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; }
Diff: PwmOscillator.h
- Revision:
- 0:9e0f295a55a4
- Child:
- 1:4bbb380a1089
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/PwmOscillator.h Fri Dec 14 14:34:22 2012 +0000 @@ -0,0 +1,22 @@ +#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(); +};