Support for new board coming up: Tang Nano 20k

[Peter-van-Tol]

I'm happy to announce that LiteX-CNC will support the Tang Nano 20k in the near future. Sipeed was kind enough to send a sample to be used as test-bed. A HAT for using the Tang Nano with a RapsberryPi has been drafted. This HAT will provide:

• 7 extended PMOD connectors, each providing 4 GPIO, power and the ENA-signal from the watchdog;
• 1 RS489 connection for connecting a VFD.

This HAT will provide with 28 GPIO, which can be used for a config with:

• ESTOP in;
• 4 stepgen (8 GPIO in total)
• 4 home switches (4 GPIO)
• 3 inputs (ALARM, toolsetter, probe)
• connection for MPG (with handwheel, axis selection, speed selection, start, stop and E-Stop) - 11 GPIO in total

Advantage of using the Tang Nano is that you don't need to replace buffers and the inputs are 5V tolerant from the factory. When 28 GPIO is sufficient, then this board looks promising.