DFB1r4 design discussion thread

General discussions or ideas about hardware.
Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf » Mon Aug 23, 2021 11:17 pm

We are sorry that your order is incomplete... This is due to a stock discrepancy in our Distribution Centre.

The missing items... ​​​​​​have been placed on back order and will be despatched to you as soon as they become available. Estimated date of delivery, approx 8 weeks.
:|

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Falcdate Use the internet to work around dead Falcon NVRAM battery
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DFB External 030 and AltRAM for the Falcon (under development)

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exxos
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Re: DFB1r4 design discussion thread

Post by exxos » Mon Aug 23, 2021 11:42 pm

Ah man that sux. Always feking something with JLC :cussing: its all why I gave up with getting the birdseed motherboards done as just had enough in the end :roll:
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Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf » Tue Aug 24, 2021 1:43 pm

exxos wrote:
Mon Aug 23, 2021 11:42 pm
Ah man that sux. Always feking something with JLC :cussing: its all why I gave up with getting the birdseed motherboards done as just had enough in the end :roll:
Ah, I forgot to say: that was Farnell. My 2x 32MB memory.

So I ordered the more expensive one up (from Micon as I've seen that works with the TF boards). Now it's...
We regret to inform you that your consignment may be subject to a delay due to a Customs issue beyond our control and which we are working hard with the appropriate parties to resolve.
!!

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Falcdate Use the internet to work around dead Falcon NVRAM battery
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
DFB External 030 and AltRAM for the Falcon (under development)

Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf » Sat Sep 11, 2021 8:01 pm

First signs in the wild of the DFB1r4 in bring-up configuration (no RAM, flash or bus transceivers).

Wish me luck! :?

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dfb1r4_prebringup.jpeg
dfb1r4_prebringup.jpeg (212.15 KiB) Viewed 213 times
Falcdate Use the internet to work around dead Falcon NVRAM battery
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
DFB External 030 and AltRAM for the Falcon (under development)

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JezC
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Re: DFB1r4 design discussion thread

Post by JezC » Sat Sep 11, 2021 8:41 pm

Looking good so far... fingers crossed for some positive progress with this!
:thumbup: :goodpost: :coolpics:

Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf » Sat Sep 11, 2021 10:01 pm

Hmm. Failing at (almost) first hurdle.

Bus Arb seems to be working, the processor starts trying to read 0x000000 from the motherboard, but never gets a DTACK. Instead BERR fires around 100 cycles later.

What could cause that?

If the cycle were not being seen by COMBEL, we'd not get a BERR, would we? I suppose a stuck address line that just happened to fall in a region without peripherals (is that possible) could do it? Scoping all the address lines does suggest they're correctly set to all zeros.

As the processor gets BERR on this first read, nothing else happens afterwards.

I've gone through the firmware and really cut it down (making sure I'm not driving XDTACK high or something). The onboard processor boots happily in DISABLE mode.

A chin-scratcher.

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Falcdate Use the internet to work around dead Falcon NVRAM battery
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
DFB External 030 and AltRAM for the Falcon (under development)

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exxos
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Re: DFB1r4 design discussion thread

Post by exxos » Sat Sep 11, 2021 11:27 pm

Where are you testing the address zero at , on the booster board ? I'd assume you have a bad connection and combel is seeking some other ( wrong ) address and does not issue dtack, I'd assume one of the higher address lines is broken between the booster and motherboard.
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~

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Re: DFB1r4 design discussion thread

Post by Badwolf » Sun Sep 12, 2021 2:08 pm

exxos wrote:
Sat Sep 11, 2021 11:27 pm
Where are you testing the address zero at , on the booster board ? I'd assume you have a bad connection and combel is seeking some other ( wrong ) address and does not issue dtack, I'd assume one of the higher address lines is broken between the booster and motherboard.
I tested A1-A15 on the cartridge port, but, yeah, I could only probe A16-23 on the pin on my board.

You're probably right, though. Must be one of those top lines. My mobo has had connection problems on the expansion port before & have had to reseat cards a few times often. No joy with reseating this one, though, so I might get some fine sandpaper on the terminals.

I should probably invest in some deoxit as my WD40 contact cleaner doesn't do much, it seems.

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Falcdate Use the internet to work around dead Falcon NVRAM battery
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
DFB External 030 and AltRAM for the Falcon (under development)

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Re: DFB1r4 design discussion thread

Post by exxos » Sun Sep 12, 2021 2:12 pm

Maybe try resoldering the port ? I've had 100s of ram boards in and out of my falcon , had to resolder it a while back. No problems since.
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~

Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf » Sun Sep 12, 2021 5:08 pm

exxos wrote:
Sun Sep 12, 2021 2:12 pm
Maybe try resoldering the port ? I've had 100s of ram boards in and out of my falcon , had to resolder it a while back. No problems since.
Yes. Good idea. It's overdue, to be honest.

I have to have the board out of the case to fit the spanky new fan the Exxos store fairy delivered to me anyway. :D

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Falcdate Use the internet to work around dead Falcon NVRAM battery
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
DFB External 030 and AltRAM for the Falcon (under development)

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