MAX3421E <> F0

WIP example app using custom furi glue for tinyusb, to allow the Flipper Zero to use the MAX3421E as a USB host controller.

Doing all testing with https://www.adafruit.com/product/5858 currently. Previously was trying with https://www.amazon.com/dp/B01EWW9R1E, 2 of 2 chips bought from Amazon wouldn't properly respond over SPI — recommend avoiding this product and/or seller.

F0 pins as follows:

• (Default external SPI) MISO = PA6
• (Default external SPI) MOSI = PA7
• (Default external SPI) CLK = PB3
• (Default external SPI) CS = PA4
• INT = PB2

TODO:

• Cleanup worker, setup proper callbacks w/ stream buffer & textbox
• Figure out why MAX never asserts OSCOKIRQ post-issuing USBCTL CHIPRES
  • Others have reported this as a chip misdesign
  • test replacing wait for OSCOKIRQ w/ simple delay
  • PR tinyusb?