Adds support to the core for PIO-based, software-created UARTs, up to 8 (the number of PIO state machines) possible.
By using a custom program on the PIO state machines, it allows for very high bit rates and does not require CPU or interrupts.
Bit widths from 5- to 8-bits, 1 or 2 stop bits, and even/odd/none parity are supported.
Earle F. Philhower, III
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