Add initial ParallelBus support for ESP32-S2

[kmatch98]

I updated and commited a new revision that gives more pin options. See note below.... This is ready for review.

Special Note:

Due to what I think is a limitations of the ESP32-S2 that prevents writing a single byte (8-bits) to the output register (32-bits, I had to modify the code to write a full 32-bit chunk to the register. I would like feedback if there are faster methods for writing out the data (see lines 214-236).

(Note: If using the same register for the data lines and the write line, so I can clear the write line at the same time as writing the data. I verified that I could eliminate the "clear_write" line with no negative impact on the operation, but with approximately 13% total time reduction.)

Verified on the following hardware:

• ESP32-S2 Saola Wrover demo board (ESP32-S2 Saola 1R Dev Kit featuring ESP32-S2 WROVER, Adafruit product ID: 4693)
• 320x240 LCD display using ILI9341 display driver (2.8" TFT LCD with Touchscreen Breakout Board w/MicroSD Socket - ILI9341, Adafruit product ID: 1770)
• CircuitPython version 6.1.0: 6.1.0-rc.1-15-g6a76b6002-dirty on 2021-01-22; Saola 1 w/Wrover with ESP32S2

Benchmark results

200x writes of purple.bmp using a forced refresh display.refresh() for each write:

• PyPortal: 34.9 seconds (running 6.0.0-alpha.3-33-gd600759bc-dirty on 2020-09-10; Adafruit PyPortal with samd51j20)
• Saola ESP32-S2: 23.3 seconds (running 6.1.0-rc.1-15-g6a76b6002-dirty on 2021-01-22; Saola 1 w/Wrover with ESP32S2

[kmatch98]

I evaluated the impact of bit manipulation to convert the 8-bit data into the 32-bit register. For everything I tried, I saw no significant impact on the performance. If you have any recommendations on speeding it up, I'll be glad to try them.

[kmatch98]

I added capability for data and write pins >= pin #32. Also, the data and write pins can be in different registers (0-31, or 32+).

This is now ready for review. Best is to compare against the SAMD or NRF ports.

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I verified on the following hardware:

• ESP32-S2 Saola Wrover demo board (ESP32-S2 Saola 1R Dev Kit featuring ESP32-S2 WROVER, Adafruit product ID: 4693)
• 320x240 LCD display using ILI9341 display driver (2.8" TFT LCD with Touchscreen Breakout Board w/MicroSD Socket - ILI9341, Adafruit product ID: 1770)
• CircuitPython version 6.1.0: 6.1.0-rc.1-15-g6a76b6002-dirty on 2021-01-22; Saola 1 w/Wrover with ESP32S2

Tests:

I verified the use of data0 pins in the lower register (pins #8-15), with either write pin #3 or write pin #33.
Still unverified:
I don't have hardware that breaks out pin 32, so I could not verify operation with data0 pins in the higher register (32+).

[tannewt]

Just one question and a request. Looks good overall. Thanks for taking this on!

[tannewt]

Thank you!