CHOCHI F - with USB power, USB-serial (maybe) and uSD card

[enso]

Finally, the new boards (rev F) arrived, and I am torturing them now...

The F revision adds a uSD card slot in exploratory mode: power is hardwired and 5 pin headers can be jumpered to the expansion port above. I haven't had a chance to get the SD card software working, so this should help. I could use some help with this if anyone has a little free time...

The CP2102 port is now recognized by my Linux box, but I am still debugging the serial interface.

EDIT: The board is stable. I have 8 of these for $25 each. USB power is fine, but the on-board USB-serial port is not functional, and is bypassed (the board requires a 3.3V USB-serial connection, just as the previous boards). The picture shows a prototype that has been reworked quite a bit - your board will be much cleaner.

[enso]

I just checked EhBASIC for the weird behaviour documented in the CHOCHI E thread... It works as expected:

BASIC.png (2.58 KiB) Viewed 3032 times

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[mkl0815]

Really, really impressive. What's the size of the board? 6cm by 6cm?
Mario.

[enso]

Thanks, Mario. 5cm square.

[BigDumbDinosaur]

enso wrote:

Thanks, Mario. 5cm square.

Nice soldering on the PLD package. How did you do that?

[enso]

The usual solder paste/stencil method, hotplate to reflow.

[barrym95838]

enso wrote:

... your board will be much cleaner.

I don't see how that's possible ... the picture that I'm viewing seems incredibly clean already!

Mike

[enso]

The prototype in the picture was hand-assembled in several stages for testing - first the USB connector and power regulators, then the FPGA and the flash... Some components were hand-soldered (you can see the bigger caps are all crazy), and when I took the picture the SRAM had solder splattered on its pins from messing with the capacitors. The final boards will be much neater, no kidding.

[lordbubsy]

That soldering looks impressive! I wish I’d dare something like that. I have a CPLD in VQFP-44 package to practice with. That’s 0,8mm (0.031").

I believe the package what you have there is TQFP, which is 0,5mm (0.02")?

Nice work!

Btw, the CP2102 works flawlessly under windows. I’ve been using them for years now. I also attached them to the C64’s userport. For what’s worth...

[enso]

lordbubsy wrote:

...I believe the package what you have there is TQFP, which is 0,5mm (0.02")?

Yes indeed. Thanks!

Quote:

Btw, the CP2102 works flawlessly under windows. I’ve been using them for years now. I also attached them to the C64’s userport. For what’s worth...

I've been using CP2102 boards from EBay for years! I haven't figured out what's wrong - the USB side works (my computer recognizes the port) but connecting RX/TX pins does not create an echo. The FPGA serial port works fine with the bypass pins. So somehow the 2102's RX and TX pins are not connected. I'll take another look at the board, but I am just about ready to give up. The tiny qfn is a real pain to solder, so it's possible it shorted under the chip.

In the meantime, the F boards work fine, they just need an external USB-serial cable connected to the three-pin GND-RX-TX connector just above the CP2102.

[enso]

Posted more details about the board and SD-Card support on the CHOCHI website:

Code: Select all

http://apple2.x10.mx/CHOCHI/#[[CHOCHI%20F%20diagram]]%20[[CHOCHI%20F%20SD%20Port]]

Sorry, this board does not support [[ and ]] inside URLs - please copy and paste.

CHOCHI_F_SD.png (42.64 KiB) Viewed 2808 times

The attachment CHOCHI_F_diag.png is no longer available

[BigEd]

(This link should work - %5B and %5D for the square brackets.)

[enso]

Here is how to connect a power switch.

powerswitch.png (49.26 KiB) Viewed 2905 times

I usually solder in a 2-pin header and keep a jumper on it. Now I can disconnect the power to the FPGA to reboot the entire board into a clean bootloader.

The trace on the back is thin and can be easily scratched across with a sharp implement or a Dremel tool.

[enso]

Justin pointed out that the SD wiring diagram posted above and on the web site was incorrect (I was off by one pin). The silkscreen on the bottom is correct.

If you've connected the SD port using the old diagram, please check the new diagram and your circuit as it will not work.

Many apologies for my sloppiness. Diagrams are now fixed.

[lordbubsy]

I got the board this week, it looks even better then on the photo! Thanks enso. I applied the on/off and the reset switches. It’s running fine. I will try to assemble some tests and making a template using ACME. It's only understanding 6502, not 65C02?