Capacitor help (sawtooth signal)

[danielclark]

Hi guys, I am using a PIC Micro to generate a signal of 11hz per second (i.e. it pulses 0 and 1 eleven times per second), which will generate a squarewave signal.
I want to modify the signal to output a 'sawtooth' signal. How do I calculate the capacitor value to use?

Is there a formula to use where I input Voltage, frequency etc.

Thanks

[Steve Conner]

If you want to convert a square wave to a sawtooth, you need more than just a capacitor, you need an integrator with a reset switch.

Go and look at the schematics for a Roland JX-3P or whatever, these have square wave oscillators that are converted to sawtooth by an analog circuit.

If a somewhat misshapen sawtooth is acceptable, you can use a RC network with a diode across the resistor to sharpen the falling edge of what would otherwise be a misshapen triangle wave, and adjust the duty cycle of your PIC output to suit. The time constant R*C should be about 5-10 times longer than the period of your wave.