DFB1r4 design discussion thread

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

Post by Badwolf » Thu Aug 12, 2021 9:43 pm

...and having seen the difference in price for a 4 layer board versus a 2 layer at JLC, I now remember why rev 3 was only 2 layer. :|
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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 » Thu Aug 12, 2021 9:57 pm

Yep. Most of my stuff is 4 layers now. Even my DULATOS boards are 4 layers these days. After being stung by 2 layer boards costing me £100's, cheaper in the long run just to do it right in the first place.
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Badwolf
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Re: DFB1r4 design discussion thread

Post by Badwolf » Tue Aug 17, 2021 12:40 pm

So after a few different sanity checks this is what I currently have.

Screenshot 2021-08-17 at 12.23.54.png
Screenshot 2021-08-17 at 12.23.54.png (662.93 KiB) Viewed 392 times

I've changed from my old Atmel JTAG connector to the straight-six used by the TF boards (why not?), but otherwise everything else checks out.

Compiling the (very basic) firmware I'm using for DFBr3b2 with the pinouts used by this board results in a successful build and it (just) fits in an XC144XL.

Screenshot 2021-08-17 at 12.30.19.png
Screenshot 2021-08-17 at 12.30.19.png (85.6 KiB) Viewed 392 times

My cardboard cutout version seems to sit clear in the Falcon too -- PSU, hard drive mount and all. The top shielding is a no-no, obviously.

My only real outstanding niggle is should I switch to a through-hole PLCC socket. I used the SMT one out of habit, but they are a bugger to solder.

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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 » Tue Aug 17, 2021 2:20 pm

Through-hole PLCC socket version.

Hmm. Better?

Screenshot 2021-08-17 at 14.14.18.png
Screenshot 2021-08-17 at 14.14.18.png (675.78 KiB) Viewed 385 times

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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 » Tue Aug 17, 2021 2:29 pm

Looking good :)
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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 » Tue Aug 17, 2021 8:52 pm

Bugfix!

I had considered going 32-bit on my flash ROM and had started relabelling my ROM sheet for upper and lower word chips. I'd dropped the idea as I was tight on board are, it'll be cheaper with a single chip and whilst the speed boost would be considerable, the flash ROM is only an option, so I didn't think it worth it.

However I forgot I'd started this and had laid up the board with (chip) A0 wired to (CPU) A2. Oopsie!

Glad I spotted that one as a bodge wire on those pins would have been very awkward.

Current version:

Screenshot 2021-08-17 at 20.42.11.png
Screenshot 2021-08-17 at 20.42.11.png (31.98 KiB) Viewed 361 times

I also had a change of heart over splitting the RW line into booster-side and Falcon-side. Why add complexity, I thought? So now the boards RW line is directly connected to the expansion XRW header again.

But three changes of heart (RW, JTAG header and socket type) and a major bug spotted in one day have put me off ordering for today. Think I'll give it another 24 hours to pick up further booboos.

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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 » Wed Aug 18, 2021 5:33 pm

More changes to the ROM schematic and board:

Screenshot 2021-08-18 at 17.34.13.png
Screenshot 2021-08-18 at 17.34.13.png (73.74 KiB) Viewed 333 times

RS won't have any 512kB 5V Flash ROMs in stock until December. They might have some 1MB ones in October, though...

Why not route one extra address line to the CPLD to allow ROM bank switching or even support for the new 1MB EmuTOS?

Can't hurt, can it?

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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 » Fri Aug 20, 2021 12:02 pm

Well, the button has been pressed. The order is in.

Cost me 4x what the rev3 did. Half of that is on going four layer, the other half is extra fees & taxes. This is getting too expensive!

BW
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 » Fri Aug 20, 2021 12:51 pm

Badwolf wrote:
Fri Aug 20, 2021 12:02 pm
Cost me 4x what the rev3 did. Half of that is on going four layer, the other half is extra fees & taxes. This is getting too expensive!
Know that feeling!
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
Posts: 454
Joined: Tue Nov 19, 2019 12:09 pm

Re: DFB1r4 design discussion thread

Post by Badwolf » Fri Aug 20, 2021 1:39 pm

exxos wrote:
Fri Aug 20, 2021 12:51 pm
Badwolf wrote:
Fri Aug 20, 2021 12:02 pm
Cost me 4x what the rev3 did. Half of that is on going four layer, the other half is extra fees & taxes. This is getting too expensive!
Know that feeling!
I've checked everything I can think of twice and even went to the extent of 3d printing a fake board yesterday to follow up from the cardboard one to make sure the damned thing will fit!

IMG_4578.jpeg
IMG_4578.jpeg (202.73 KiB) Viewed 293 times

I hope to christ this one works! :?

BW
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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