Clock circuit issues

[DerpymanMT]

Hey all! I’ve just gotten my parts, but now I’m in more of a doozy, I have check Garth’s primer as everyone suggests to, and the clock circuit needs a 68pf capacitor and a 5.6k resistor, but with the limited budget and me forgetting to get it, I don’t have it, I have a 1mhz 4 pin crystal oscillator but it just won’t output clock for the w65c02s and I was told that the CPU can take that. I have also seen Ben Eater’s video and saw his wiring.
The resistors that I have only go up to 3k and my capacitors say 22 and 104. If the primer was asking for electrolytic capacitors, are only 100uf and 10uf is there anything I could do to remedy this situation, I do have things I could take parts out of but I wouldn’t count on it...

[GARTHWILSON]

DerpymanMT wrote:

Hey all! I’ve just gotten my parts, but now I’m in more of a doozy, I have check Garth’s primer as everyone suggests to, and the clock circuit needs a 68pf capacitor and a 5.6k resistor, but with the limited budget and me forgetting to get it, I don’t have it, I have a 1mhz 4 pin crystal oscillator but it just won’t output clock for the w65c02s and I was told that the CPU can take that.

Be sure to read the notes under the circuit there at the top of the circuit potpourri page. There are several clock options. The 68pF and 5.6K are only for if you're using an RxC clock. You won't want them if you're using a crystal oscillator.

Quote:

The resistors that I have only go up to 3k and my capacitors say 22 and 104. If the primer was asking for electrolytic capacitors, are only 100uf and 10uf is there anything I could do to remedy this situation, I do have things I could take parts out of but I wouldn’t count on it...

If you have a 5V regulator right near the computer circuit, you probably won't need the electrolytics. Their value is not critical anyway, and you stray quite a ways in either direction and not notice any effect. (That's not the case with the 68pF above though. If you use the RxC oscillator (which WDC no longer recommends), the frequency will be approximately inversely proportional to the value of that capacitor.)

[DerpymanMT]

Ok I think I got it and just to be sure I had hooked up some leds to the cpu and voila! It is just flickering pretty fast btw is it supposed to be that fast because in Eaters video it was pretty slow, or was that just because of his clock speed settings? Anyways I really need to read the whole thing before asking, but that is what this forum is for asking for help!

I added the LEDs to the address pins and it is just flickering on and off really fast!


Sorry for bothering ya!

-EAS

[Chromatix]

With a 1MHz clock, the 6502 will execute 500,000 NOPs per second, iterating through the 64KB address space 7.6 times a second. So yes, you should see the A15 line flash very quickly but regularly.

[drogon]

DerpymanMT wrote:

Hey all! I’ve just gotten my parts, but now I’m in more of a doozy, I have check Garth’s primer as everyone suggests to, and the clock circuit needs a 68pf capacitor and a 5.6k resistor, but with the limited budget and me forgetting to get it, I don’t have it, I have a 1mhz 4 pin crystal oscillator but it just won’t output clock for the w65c02s and I was told that the CPU can take that. I have also seen Ben Eater’s video and saw his wiring.
The resistors that I have only go up to 3k and my capacitors say 22 and 104. If the primer was asking for electrolytic capacitors, are only 100uf and 10uf is there anything I could do to remedy this situation, I do have things I could take parts out of but I wouldn’t count on it...

Sounds like you're going now, but personally, I'd stick to the can oscillator wherever possible. It's a bit more expensive and can take up a little more board space, but they "just work". It's what I've used on all my systems - AVR and 6502. (and WDC 65C02).

-Gordon