Electronics > Projects, Designs, and Technical Stuff
Sencore USB Interface Project
coromonadalix:
Pm'ed you thks for your great work.
pigrew:
PCBs have arrived... they're tiny. I'm surprised that I didn't get hit by Trump's tariffs... Logistically I don't know who I would pay, or how.
I've found a few minor issues with the schematics, but nothing insurmountable. Parts should arrive in the next few days. Next time I should look more carefully at the the amount of RAM the micro has, 6 kB is about the minimum for a STM32 USB device, it seems. I used the TSSOP-20 package, which is only shipping with minimal RAM. The QFP packages have more options.
USBTMC or CDC? I'm tempted to sit down and write a simple USBTMC driver...
Photo below, with a RMB, 10 HK$ and 25 cents, for scale.
coromonadalix:
damn tiny they are loll
ebclr:
Take a look on this little board, your work can be quite easier and cheaper https://www.electrodragon.com/product/ch552-ch554-mini-dev-board-ch55x-series/
pigrew:
--- Quote from: ebclr on September 04, 2019, 11:53:58 am ---Take a look on this little board, your work can be quite easier and cheaper https://www.electrodragon.com/product/ch552-ch554-mini-dev-board-ch55x-series/
--- End quote ---
If only it were that easy. Those CH55x might be easier to use than the STM32 (though probably not for me as the English documentation is lacking), but it wouldn't remove most of the PCB components from this project. The issue is that the circuit must speak as a MCS-48 IO expander on the bus, which requires somewhat fast timing. The CH55x doesn't look like it has that capability. Also, the Sencore bus uses TTL-drivers with 5V pull-ups, so voltage translation is still needed.
(The CH552 board also doesn't provide any isolation or ESD protection, which I also wanted...)
The FT2232H almost worked, but it's expander mode is for the MCS-51 bus, not MCS-48. The MCS-48 8243 has special op-codes to AND and OR memory locations which were dropped in the MCS-51.
ADDED LATER: Unless I'm missing some feature about the CH55x? I could have strung together a bluepill or USB-UART, isolator, another blue pill, 8243.. Would have been less design effort.
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