Atari STe SD card reader on the Extended Joystick Port

[Orion_]

Hello,
A friend of mine, Zerosquare had an original idea several years ago, about using a cheap SPI 5 volt SD card module that everyone uses on arduino, but now plugged on the Extended Joystick Port of the Atari STe (because this port provide 5 volts)
During the confinement, I had some time to work on it so I made a simple driver, like a ram disk by hooking the "hdv_bpb/hdv_rw" functions.
So you can browse your FAT16 SD card using the GEM desktop, you will need to run the "bigdos" utility at boot if you want to see big partitions up to 2Gbytes, else the TOS is limited to 32mbytes DOS partition.
You have a little demo here:
https://www.youtube.com/watch?v=2COG26-XjC0

and the driver here:
http://onorisoft.free.fr/atari/sdextjoy.zip

Since it's a cheap hardware and it use SPI "bit banging" (read one bit at a time using the 68k) the speed is pretty low, about 20kbytes/s
I'm working a on faster version, with writing capabilities, but it's barely faster (25kbytes/s)
There is nothing to buy from me, you just buy a cheap SD card 5volts SPI module from any arduino gadget reseller, plug it using the schematics provided in the zip file, boot the driver on a floppy in an AUTO folder, and voila.. (If you still want to donate and show support you can here )
I hope to work on a faster version with Zerosquare using the SD card on the cartridge port, but well, we will need another month or 2 of confinement ..

[MM41]

Great thanks Orion_ ,

[catmando]

Nice one, very neat idea

[christos]

Great idea. Would this be able to be converted to run with bjl as well?

[wongck]

wow really an original idea.

[Atari030]

I picked up one of these yesterday, seems to work on my Falcon. I think I have a bigdos problem sending the mouse and KB haywire, I'll try it on an STE as well and see. Its a pretty handy bit of kit, well done.

https://www.jaycar.com.au/arduino-compa ... e/p/XC4386

[Cyprian]

cool project @Orion_

[mlynn1974]

That is a brilliant idea! It's hard to believe in this day of 32Gb memory sticks actually on an ST a 32Mb partition would be very useful.

[simonsunnyboy]

Very nice project idea.

Also these days many SPI driven ICs are available and in use. I think there are even more possibilities for hardware gadgets on the EJP.

[Kelgors]

Love it!

I bought quite the same sd card reader and it runs nicely with my 1024 STe on EmuTOS.
Thanks for your work.

[spiny]

This is very neat Ordered some parts to make one.

Will write access ever be possible? My knowledge of the STe extended ports is low

[Dal]

https://gamesx.com/controldata/ejp_faq.htm

Section 10.1 suggests that it could be possible to write data 8bits wide across both ports.

[qazuio]

Great project, super cheap and super cool, I was going to post yesterday about using maybe 4bit wide to increase speed but,

"https://gamesx.com/controldata/ejp_faq.htm

Section 10.1 suggests that it could be possible to write data 8bits wide across both ports."

It would be amazing if that were possible - could desolder the 2 ports and mount the module internally since there's very few uses for these ports.

Would need a micro controller to convert from parallel to serial and vice versa

[Dal]

That's a nice solution - especially as the hole in the case for access to the card would already be there.

[Orion_]

and where do you see 8bits pins on the SD card ? ...

[qazuio]

"and where do you see 8bits pins on the SD card ? ..."

You don't, so that is where a dedicated micro controller or ic like MC74HC595A (I said like:-))))
Basically a shift register, for the nit pickers - I'm not advocating that I plan on making a working device - just ideas for a proof of concept, there's a lot of talented and knowledgeable electronics designers in the Atari community - if such a device were possible it wouldn't be long I'm sure before it came out.
I've ordered the SD card SPI module to have a go at the card reader idea that Orion_ posted since it looks so straightforward to put together - genius actually,

[Orion_]

the idea was to make it cheap with parts that you can already buy.
otherwise I would have come up with something on the cartridge port

[qazuio]

https://gamesx.com/controldata/ejp_faq.htm

Section 10.1 suggests that it could be possible to write data 8bits wide across both ports.

Looking at the ejp faq suggests it may be possible to read/write 16bit wide data across both (possibly more)?

[joska]

the idea was to make it cheap with parts that you can already buy.

Why not a CH376S breakout board? It's cheap, has USB and an 8-bit parallell interface that you can connect directly to the jagpad-ports or printer-port. There's also a lot of easy to understand examples of how to use it out there.

It also supports HID devices, so you can add mouse/keyboard-support.

[Cyprian]

Nice finding @joska, it could be used for /|\ hardware without extended joystick port like ST/TT, and should be faster

[joska]

I have a couple of these, I have tested it briefly on my Falcon but only via the serial port. It is very easy to access files on a USB-stick using this module. I have not tested HID at all.

[dbsys]

Brilliant idea!

[1st1]

It also should work over parallel printer port. There is such a solution in vcfed forum for IBM PCs, it only uses 3 signals. http://www.vcfed.org/forum/showthread.p ... OS-ver-1-1

[joska]

Yes, it would work, but speed would not be impressive. The printer port tops out at around 100kb/s on fast machines, a lot less on an ST. Then divide this by eight, and then by three again when bit-banging SPI.

[PlasticParty]

Amazing work. Im looking forward to seeing one that can write as well. I understand that the speeds are slow but that is a small compromise to make considering how good a solution this is.