Creativision MegaSDCart

[Scouter3d]

Hi,

i just finished drawing the schematic for the MegaSDCart :0)
For all you tech-savvys :0)

Cheers, TOM:0)

[cheshirenoir]

Nice work!

Chesh

[Scouter3d]

Thanks!

This is my biggest electronic-project so far...

btw. @username@ told me about EasyEDA and i love it!

Cheers, TOM:0)

[MADrigal]

Very excited to see it ready!

[Mobsie]

Yes, is an Amazing work and deserve all our respect to both of you

[Mobsie]

I still fight with Kicad

[nippur72]

very interesting! Can you share more details? How do you load data from Arduino to RAM? I'm doing a similar SD card project for the Apple1 where I use a VIA6522 to talk with the Arduino, because I assumed the Arduino isn't fast enough to write to the data bus.

[Scouter3d]

Hi Mobsie, i was also fighting with KiCad, but i like EasyEDA :0)

because:
1) the "handling" is much easier and consistent
2) I found all the parts allready from inside EasyEDA - as the community shares all parts within EasyEDA (and not in many different forums from where you have to import files into a very complex library system like in KiCad) I only needed to adapt an Edceconnector to the measurements fitting the CV and also that was really easy!
3) Parts automatically have assigned corresponding footprints (this was a nightmare in KiCad...)
4) It has an autorouter built in
5) i heard about it, watched 2 videos á 15min. , started creating the schematic and finished it all within 2 days... (KiCad needed many hours of tutorialvideos ...)

Cheers, TOM:0)

[Mobsie]

Great tip I will try. And good to know i al not to stupid at all

[Scouter3d]

Hi nippur72,

In the MegaSDCart design the Arduino and the Creativision "share" a common 32k SRAM, CV and Arduino are not allowed to access this RAM at the same time, so when one is using the RAM (reading or writing) the other one has to be completly disconnected from the bus... therefore the great number of ICs...

So the Arduino never writes directly to the 6502 bus

6502 and Arduino communicate with two signals:they need to check each other if they are RDY...
These signals are in fact created thru "CS" signals for $C000 and $D000 (else unused areas in the ROM0 region)
1) Arduino to 6502: Arduino sets 1 line high while he is working which can be checked by CV by reading from $C000 (either 0 or 1)
2) 6502 to Arduino: CV accesses $D000 which the Arduino inteprets as "now it is my turn"

Cheers, TOM:0)