Thanks for the correction on lexicon. I am indeed aware that it is the user I/O port, and that Serial Native Accessory Converter is a peripheral specifically to handle the 5v vs 3.3v line levels. To be clear when I said "SNAC port", I was actually talking about the female USB A port on the SNAC converter board itself, as opposed to connecting it to the user I/O port.
- MISTER-FPGA-SNAC-Adapter-HDMI-Connector.jpg (14.92 KiB) Viewed 3376 times
Both RS232 & RS485 (JVS) use 5v of course, as opposed to the 3.3v provided by the user I/O port itself.
- UARTDataExample.png (33.92 KiB) Viewed 3376 times
I'm not at all trying to hold any breath. I'd rather work with capable people as I know the original poster is. Parsing JVS is trivial. This has been solved long ago, and is well documented. If an Arduino can handle it, I'm gonna guess the Cyclone can too.
https://github.com/OpenJVS/OpenJVS
http://daifukkat.su/files/jvs_wip.pdf
Similarly folks do RS485 on Altera FPGA boards all the time, so there is no magical voodoo here.
https://www.design-reuse.com/altera/?q=RS485
Alternately you could use a MAX485 on the fingerboard / adapter used with the SNAC converter, and break the signals down to RS232 levels again, potentially requiring less code rewrites, and allowing reuse of some of the DB9 code perhaps.
https://datasheets.maximintegrated.com/ ... MAX491.pdf
I'm not gonna lie, the thought of using JVS-PAC really turns me off. I have no desire to convert signals to USB before using them. It seems pointless. I am indeed aware of the community propensity to gravitate to and defend USB, but I'm not willing to debate those semantics. Of course this is an exercise in academics, but that is part of why some of us are here. It isn't all about playing games for me, as it is finding solutions, and learning in the process.
JVSPAC, at NOK850.00 is about $100 USD, a USB to RS485 adapter is $15
https://www.amazon.com/DSD-TECH-SH-U10- ... 078X5H8H7/, and a 5 pack of Max485's on a breakout board are only $7
https://www.amazon.com/Max485-Chip-RS-4 ... 00NIOLNAG/. Obviously the most cost effective route would be a minor code change, or fork to support RS485, although it may not be the most simple route at a surface glance.
Once the base level support was figured it, it seems trivial to port the JVS parsing code to the other cores that support SNAC or DB9, I could be wrong of course.
