Home-Made TF536 does not boot

[Xata]

Hello. This is my first post, and I am usually silent, but I've tried everything I could find here and can't get past rainbow.
What I have:

• TF536 I've built from scratch
• 2022 firmware from github programmed with Xilinx Platfrom Cable
• CPU from a batch that worked for another guy
• CPU is soldered
• Tried 100mhz and 80mhz osc's, no difference
• Soldering checked under microscope and device cleaned in ultrasonic bath
• Tried with CF card and without
• Amiga 500 rev6a with licensed copy of K.S. 3.2.2

Observations:

• I get to K.S. greeting on usual 68k
• I get rainbow on boot or soft reboot
• Led gets brighter from dim
• Black screen after that
• CPLD gets hot, but touchable
• OE on SN74CB3T3245PW is always 3v3 HIGH
• 68k data lines seem to transmit same pattern over and over again
• Waiting for hour changes nothing
• Can't find CPU clock pin, but OSCs give 100/80MHz

Can somebody please propose what can I do next to understand the cause of my issue?

[terriblefire]

Can you try Diagrom?

https://www.diagrom.com/

This should help us a lot. Since you get colourbars you're getting some code running.

I have a few suspicions but diagrom will help me narrow them down

[Xata]

Can you try Diagrom?

Hello. I don't have diagrom but I will obtain it tomorrow and will post here. Thank you in advance

[Xata]

Meanwhile tried different OSC's. With 66 and 50 MHz I get "green screen" after rainbow and a reboot loop. Not sure that makes sense though as I don't quite understand the logic.

[terriblefire]

Meanwhile tried different OSC's. With 66 and 50 MHz I get "green screen" after rainbow and a reboot loop. Not sure that makes sense though as I don't quite understand the logic.

The OSC should be 100Mhz.

EDIT: Nothing else will work

[Aeberbach]

Are your SRAMs definitely around the right way?

(guess why I'm asking...)

[Xata]

Here is what I've got:

20240819_192215.jpg (166.02 KiB) Viewed 1848 times

It boots OK with regular 68k

Edit: BTW OSC is back to 100MHz

[terriblefire]

Looks like it's trying to access fastmem. Wonder if STERM is shorted or stuck somehow

@chucky

[Xata]

This is that pin, right?

Screenshot_20240819_210703_Gerber Viewer.jpg (277.06 KiB) Viewed 1818 times

[terriblefire]

will check in a bit. There is an obv file out there somewhere