Search found 234 matches

by prophet36
Sat Apr 22, 2017 11:02 am
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

I'm going to make a board with diodes Thank you so much for all your hard work so far on diagnostics. Thanks to you we now have a much better understanding of why some MD models suffer problems, and others don't. Also, thanks in advance for your work on this alternative bridge-board (irrespective o...
by prophet36
Mon Apr 17, 2017 1:19 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

One thing I don't understand is if the rapid-switching of the buffer conveying the address-lines is causing /OE to also switch, that implies that /OE is not being actively driven. But if that were the case, then putting a 4K7 pull-up to +5V on /OE on the MD side would fix the problem, but when you t...
by prophet36
Mon Apr 17, 2017 11:36 am
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

This is getting way out of my depth (as I said before, I'm no electronic engineer; I deal in 1s and 0s, not voltages and currents). Is it possible to check to see whether or not this address-line contention happens during Z80 arbitration even with a regular (i.e non-UMDK) cart? What about replacing ...
by prophet36
Mon Apr 17, 2017 9:14 am
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

Still no better. [...] This behaviour of the buffer is undefined at this voltage and it seems to flip between high and low, and I reckon that's whats causing the noise on CAS0. I agree. Unfortunately, if this is the case, then the problem cannot be fixed properly without significant changes to the ...
by prophet36
Fri Apr 14, 2017 3:46 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

OK, try this new FPGA binary. It stops driving the data bus soon after /OE deasserts, and it refuses to return the state-machine to the idle state until /OE has been deasserted for four consecutive cycles.
by prophet36
Thu Apr 13, 2017 9:46 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

How really controls VDxx bus? It's controlled by the state-machine in the bus-arbiter . It's the std_logic_vector "mdData_io". Normally it's tri-stated, but several states drive it with a signal registered from the last word read from the SDRAM controller. If it UMDK side, I have some questions. Is...
by prophet36
Wed Apr 12, 2017 9:46 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

How consistent is the time between the /OE assert and the rising-edge of the first spurious spike? I'm thinking of putting an output (maybe on the spare unused output currently labelled mdDTACK_out) to identify the Sonic1 PCM range, so we can see that alongside /OE. Regarding the address-line drift,...
by prophet36
Wed Apr 12, 2017 2:04 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

If you correlate the logic analyzer output with an instruction-trace from the UMDK, you'll get a better idea of where the R/W foo is coming from: $ loader -w $HOME/sonic1.bin:0 -x 2 -t trace.bin:1024 UMDKv2 Loader Copyright (C) 2014 Chris McClelland Putting MD in reset... Writing SDRAM... Releasing ...
by prophet36
Tue Apr 11, 2017 10:13 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

You could add logic to cover up the issue, but it doesn't fix the real problem (and I become less sure of the problem the more I look at it) OK, there are a few things we can try, to identify (and hopefully fix) the "real problem". Many of these ideas are just shots in the dark so don't be too upse...
by prophet36
Mon Apr 10, 2017 9:59 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

An interesting thing occurred to me when I looked at your 'scope traces, concerning the instruction-trace Montserrat recorded last year (when one of his consoles was crashing in a similar place, on the "SEGA!" PCM on Sonic1's intro). We saw two adjacent reads of the same PCM address : 167355419 C RD...
by prophet36
Sun Apr 09, 2017 12:43 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

OK so in summary, on the question of whether you see noise on /OE during PCM playback, keeping eveything else the same (bench PSU, same ROM, same UMDK cart, same way of measuring, same testgear etc): MD1 + Regular cart: NO MD2 + UMDK: NO MD1 + UMDK: YES At risk of jumping to conclusions from an obse...
by prophet36
Sun Apr 09, 2017 11:48 am
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

playing a sound effect in MJ's Moonwalker induces a large amount of noise on /OE Nice work. Is it possible for you to repeat that test without UMDK? With Moonwalker on a dumb flash-cart, maybe? The MDII is clean as a whistle So does that MD2 exhibit any problems with your UMDK cart? Did you use the...
by prophet36
Sat Apr 08, 2017 4:38 pm
Forum: UMDK
Topic: MD hangs after playing any PCM file
Replies: 69
Views: 16569

Re: MD hangs after playing any PCM file

So if we take the common example of Sonic 1, as soon as the game starts you get to hear the wonderful "SEGAAA" sound clip, after which the game crashes (Illegal instruction $00071FC6 in this case). This is a known issue that several people have identified[1][2][3]. The crash is in the "@busyloop" o...
by prophet36
Tue Mar 21, 2017 7:35 pm
Forum: UMDK
Topic: UMDK Manufacturing - word of advice
Replies: 10
Views: 3172

Re: UMDK Manufacturing - word of advice

I dare say that now someone else has done the work he will be selling Bridge PCBs. this man does things only for profit. I'm not sure that's true, but even if that were the case, it would be perfectly fine[1]. We all have different motivations. Please, let's not reopen old disagreements. These argu...
by prophet36
Sun Mar 19, 2017 11:03 pm
Forum: UMDK
Topic: USB device not recognised (CY7C68014A woes)
Replies: 5
Views: 1569

Re: USB device not recognised (CY7C68014A woes)

I would try de-soldering the 22pF caps on the oscillator circuit and replacing them.