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PlusCart(+) + SD


Andrew Davie

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Here's my beefed-up PlusCart running with a SD-card reader.  Working title, I think, "PlusCart Duo". Design/programming by the brilliant @Al_Nafuur. We're currently discussing what actual need/use there is for a SD card on a PlusCart, because most/all use-cases appear to be covered by the Offline ROMs functionality. I happen to think having a SD card also is pretty cool, but there does not seem to be much justification for one. Anyway, this is one of only two currently in existence - the other belonging to @Fierodoug5. Running the merged UnoCart/PlusCart code, so it's a rare beast. This prototype is currently not going to be supported/produced, but I thought it worth sharing the idea.

 

 

IMG20210211173213.jpg

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6 minutes ago, Fierodoug5 said:

You can put it back together with one of Andrew's new breakout boards. ?

Getting there... this software is very difficult to use.

While I'm at it, I'm considering changing the shape of the board itself to an Atari logo-shape.

Edit: maybe not the shape; but a part of the design somehow

 

991576455_ScreenShot2021-02-12at1_03_06am.thumb.png.e827e3c2e8ae8e419594c3e0f91c28e6.png

Edited by Andrew Davie
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12 minutes ago, Andrew Davie said:

Getting there... this software is very difficult to use.

While I'm at it, I'm considering changing the shape of the board itself to an Atari logo-shape.

 

991576455_ScreenShot2021-02-12at1_03_06am.thumb.png.e827e3c2e8ae8e419594c3e0f91c28e6.png

if you double the DATA bus (connect PC0-PC7 to PE8-PE15) we would have a hybrid DIY breakout board for UnoCarts, PlusCarts (and all variants that can be build with the code).

 

BlackPillToo.thumb.png.3ff110200c960122a40be5167eb73ace.png

 

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2 hours ago, Andrew Davie said:

Just a quick question - are we limited to the stm32f407vgt6?

I understand this is a 70MHz board. The stm32f407vet6 appears to be a 168MHz board. 

Could we upgrade?

 

No, both have the same MCU core and are specified to run at 168Mhz. The (only) difference between them is the flash ROM size the STM32F407VGT6 has 1 MiB flash and the VET6 only 512 KiB.

 

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I've finished hooking up PC0-PC7 to PE8-PE15, designed added and hooked up the MicroSD part, and done all the routing.

Routing takes me hours and hours and hours because it has to be neat and pretty, and minimising "via"s is often tricky.

This goes through the error checking with no board errors, but "unconnected lines" in the dimensions layer.

I am not skilled enough at this tool (Eagle) to understand how to fix that quite yet, so this may take a while...

2092461580_ScreenShot2021-02-13at1_18_00am.thumb.png.5cc3e76f351e651ac3e98c38c2d703f4.png

 

Look at all that wiring!

 

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OK, here's a first-pass. I, of course, haven't had a chance to get this built yet. So, caveat emptor.

The zip file contains the Eagle .brd and .sch file which should let you edit/change it yourself.

I've also added the rudimentary MICROSD library object that I built for this. You'll want to use MICROSD2, the one with the footprint.

The Gerber files are included - these were generated by PCBWay's export script. I use them. They're good.

 

742222056_ScreenShot2021-02-13at10_13_38pm.thumb.png.902659c6b2ba47e75943e437e84f1e62.png

 

I've put in a cutout (top right) with room for a jumper. The other jumper position is inaccessible and hard-shorted.

I may move that logo; I think it will look OK on manufacture, but another option is to put the (+) where Pluscart is, and move PlusCart above the row of pins. That might be better, but I've been fighting this software (Eagle) all day and I've had enough for now.

The spacing is hard to estimate/calculate. I'm trying to get things so that the very edge of the slot on the MicroSD reader will be flush with the outer edge of the cartridge shell. This relies, of course, on a specific microsd reader. The MicroSD will need to be attached in a rather odd way; bottom of MicroSD board placed flat on the logo side of the PlusCard board, so that the insert-slot is upwards, and then pins pushed through the 6 holes and soldered. Needs to be as flat as possible, so no spacing at all between boards. Lucky, the MicroSD I use (will link) has both the 10K pull-up resistor required, and a completely bare bottom.  It's not a common shape anymore, it seems -- but here:

 

https://www.aliexpress.com/item/4000838978416.html

 


 

PlusCartUnified 2021.02.13.zip

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26 minutes ago, Andrew Davie said:

OK, here's a first-pass. I, of course, haven't had a chance to get this built yet. So, caveat emptor.

The zip file contains the Eagle .brd and .sch file which should let you edit/change it yourself.

I've also added the rudimentary MICROSD library object that I built for this. You'll want to use MICROSD2, the one with the footprint.

The Gerber files are included - these were generated by PCBWay's export script. I use them. They're good.

 

742222056_ScreenShot2021-02-13at10_13_38pm.thumb.png.902659c6b2ba47e75943e437e84f1e62.png

 

I've put in a cutout (top right) with room for a jumper. The other jumper position is inaccessible and hard-shorted.

I may move that logo; I think it will look OK on manufacture, but another option is to put the (+) where Pluscart is, and move PlusCart above the row of pins. That might be better, but I've been fighting this software (Eagle) all day and I've had enough for now.

The spacing is hard to estimate/calculate. I'm trying to get things so that the very edge of the slot on the MicroSD reader will be flush with the outer edge of the cartridge shell. This relies, of course, on a specific microsd reader. The MicroSD will need to be attached in a rather odd way; bottom of MicroSD board placed flat on the logo side of the PlusCard board, so that the insert-slot is upwards, and then pins pushed through the 6 holes and soldered. Needs to be as flat as possible, so no spacing at all between boards. Lucky, the MicroSD I use (will link) has both the 10K pull-up resistor required, and a completely bare bottom.  It's not a common shape anymore, it seems -- but here:

 

https://www.aliexpress.com/item/4000838978416.html

 


 

PlusCartUnified 2021.02.13.zip 182.4 kB · 1 download

Great work!

 

 

  • The PCB is a hybrid board for the PlusCart and UnoCart, so there should be both names (logos) on it (or a new name like MultiBoard, UnifiedBoard, MultiPCB or HydraBoard, ..)
  • Because it is DIY and includes soldering, I would try to omit the unnecessary PINs from the PCB to the STM board
  • We should involve @electrotrains and @MacRorie ( I have asked @Albert to switch the club from private to open. But that's not done yet, so  I'll send them a invitation)
  • I like groundplanes (with fill orphans)

 

just my 2 cents

 

 

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2 minutes ago, Al_Nafuur said:

Because it is DIY and includes soldering, I would try to omit the unnecessary PINs from the PCB to the STM board

My OCD hates! unsoldered pins.  Really you just plug in the components and solder all the pins and you're done.

Not sure what you're asking - for the board to be cutaway from all unused pins...?  Ugly.  Even the original didn't do that.

 

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1 minute ago, Andrew Davie said:

 

Not sure what you're asking - for the board to be cutaway from all unused pins...?  Ugly.  Even the original didn't do that.

 

My first 5 protype boards had all PINs, but the "production" boards have omitted some of the unnecessary PINs:

grafik.thumb.png.4a20b8978d4012677677aa499049790d.png

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