Search found 12 matches

by River-of-Dust
01 Sep 2022, 09:05
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

Hi! Huh, I see. Well, I tried setting it up to trigger on PH_B transitioning to Low, but it just triggers right as soon as I plug it in. Perhaps this is an artefact of plugging it in? Is there a way to bodge in an actual RESET button? I'm not sure what to do at this point, as it seems that some part...
by River-of-Dust
25 Aug 2022, 09:47
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

Hi! Interesting! Well, the odd thing is that it's not as consistent as I thought. The blinkenlights always freeze, and they usually freeze with all four illuminated, but sometimes with only two, and (rarely) with none of them illuminated. Further, I have just discovered that even when the same light...
by River-of-Dust
23 Aug 2022, 09:21
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

Hi! Thank you for the additional information! Today, I ran some more tests with the logic analyzer probes connected as you suggested, and I found three interesting things: (1) The program counter does NOT seem to be following the 5a ROM code properly, as far as I can tell. It does for a bit, then ju...
by River-of-Dust
08 Aug 2022, 10:45
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

OK, here I realize just how much of a novice I am at electrical engineering. As a computer science graduate, I understand the concept of what you want me to check, but as a guy who also picked up a soldering iron, I'm having to learn a lot more to figure out how to suss out exactly where the fault i...
by River-of-Dust
14 Jul 2022, 05:54
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

Okay, I ended up thinking that rolling my own logic analyzer with an Arduino might be more than I have time for right now, and why re-invent the wheel. So, I googled around and was shocked to find that cheap logic analyzers are actually around $10-15! If I had known that, I would've gotten one earli...
by River-of-Dust
27 Jun 2022, 03:59
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

5) Okay, I found time to test the resistors, and I measured the following (all okay, basically): R1 = 0.997M R2 = 1.004K R3 = 2.218K R6 = 2.216K R7 = 2.218K R10 = 2.195K R19 = 2.211K Now, I'll need to find the time to write a sketch for my Arduino Mega (well, Keyestudio Mega Plus, but same thing) to...
by River-of-Dust
22 Jun 2022, 08:07
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

Thanks! Here's what I've found time for so far: 1) I ordered another oscilloscope probe and finally got some time to try it out. I captured the attached pictures when the probes and scope were all set to 10x. (I'm still new to using an oscilloscope, and I'm still puzzled why the ground wires of near...
by River-of-Dust
15 Jun 2022, 00:39
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

Oh, and that last scope capture was of U3 pin 11, I believe. Looks like my camera caught it just as the signal was jumping a bit. It was mostly stable, but it did jump around a little bit, as if the signal was changing in some way. Staying on a 1 or a 0 longer, I guess. -Derek Need to head out so I'...
by River-of-Dust
13 Jun 2022, 04:42
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

Need to head out so I'll keep this short. Refer to page 3 of the Gigatron schematic. Are you comfortable pulling U1 and connecting CLK1 (output)/RST_B (input)/PL_B (input)/PH_B (input)/PC[15:0] (input) to your Arduino and single step through the entire PC incrementing per https://raw.githubusercont...
by River-of-Dust
12 Jun 2022, 09:57
Forum: Support
Topic: Not functional; Blinkenlights static
Replies: 21
Views: 1533

Re: Not functional; Blinkenlights static

1) You're going to want to look at the clock visually on an oscilloscope to make sure it has the right voltage levels and a monotonic rising edge. Do you have access to one? 2) If you're measuring 5V at U3-11, I was hoping that meant PC3 was stuck high. It's not clear to me if your Gigatron is just...