Increasing the frequency to GP32 (Sample at 4Mhz or higher)

Johanny — Sat, 14 Apr 2007 05:39:51 GMT

I wish to sample a video signal to high frequency and the bus frequency in this case (GP32) is 4.9152 Mhz/4 (aprox 1Mhz) therefore i need a way to increse this frequency.

I hope your opinions...

PSD: I can´t change this device (neither camera or microcontroller)

Thank You!!

Re: Increasing the frequency to GP32 (Sample at 4Mhz or higher)

rocco — Sat, 14 Apr 2007 07:02:00 GMT

Hi, Johanny:

I don't quite understand what you mean when you refer to your clock.

Are you saying that the clock that is coming in to the chip is 4.9152 MHz? or is it 4.9152/4, or 1.2288 MHz?

If it is the former, there is not much you can do, outside of changing the clock. It is too fast to use the phase-lock-loop to generate your bus clock.

If the input clock frequency is 1.2288 MHz, then you can use the phase-lock -loop to generate a bus clock of darn-near 8 MHz, which is as fast as a GP32 can go.

To use the phase-lock-loop, you would need the filter components on your board. They consist of a resistor and two capacitors, hooked up to pin 42 (qfp). If you don't have them, it may be easier to change the oscillator to 32 MHz, which will give you an 8 MHz bus clock.

I'm still not sure if it will be fast enough to sample video, however. How do you intend on sampling? With the ADC (which is limited to about 59 KHz) or with external circuitry?

topic Increasing the frequency to GP32 (Sample at 4Mhz or higher) in 8-bit Microcontrollers

Increasing the frequency to GP32 (Sample at 4Mhz or higher)

Re: Increasing the frequency to GP32 (Sample at 4Mhz or higher)