Functional touchscreen example in rust

Variants/3248S035C/Examples/1-Draw/README.md

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+# A no_std Rust Example for the LCD + Touch Controller
+
+This example:
+
+- polls the XPT2046 touch-screen controller in an embassy task
+- sends the touch events to another embassy task
+- draws a polyline of the touch locations since the start of this touch event
+on the LCD.
+
+NOTE: It is not particularly stable or polished, but does work.
+
+## The code its for modified hardware
+
+It was originally written for the hardware in an un-modified form, but the current
+commit is for a modified version of the hardware.
+
+### What was modified?
+
+- Lifted XPT2046 sck, din, dout pins and tacked kynar wires over to GPIO22, 26
+and 39.
+
+![tack wired](doc/tack_wired.jpg)
+
+### Why the mod?
+
+- It worked as-shipped, but they reused the same SPI bus for the LCD and touch
+XPT2046.  The LCD can run at 80MHz, while the XPT2046 can run at 2.5MHz and that
+was severely limiting the screen update performance.
+
+### How to get the code back in alignment with the original hardware?
+
+To go back to the stock hardware and sluggish screen updates, you can use one
+embedded_hal_bus::CriticalSectionDevice for the LCD and another for the touch
+controller, both given the same embedded_hal::SpiDevice reference.  These will
+be used instead of the embedded_hal_bus::ExclusiveDevice instances in the
+current code.
+
+## Where to find the device for purchase?
+
+[Amazon linik to device this was tested on](https://www.amazon.com/dp/B0D4VCL6GR?ref=ppx_yo2ov_dt_b_fed_asin_title)
+
+This device doesn't provide documentation.  The pinout doesn't match the
+official CYD.  It is a 320*480 LCD with resistive touch-screen with a what
+appears to be an ILI9486 controller in BGR565 mode, and an XPT2046 touch
+controller.  This is nearly identical to the CYD, other than the larger frame
+buffer on the ILI9486 vs the ILI9341 on the official CYD.
+
+I did find the following repository that includes an image of the ESP32 pinout,
+though the blue/green LEDs are swapped relative to that image:
+[Board support package for Sunton ESP32-3248S035](https://github.com/ardnew/ESP32-3248S035)
+
+![Unofficial ESP32-3248S035C](doc/Unofficial_ESP32-3248S035C.png)
+
+## How to convert this for use with the Official CYD?
+
+If you choose to convert/test this on a genuine CYD, I'd recommend making a few
+changes to start:
+
+- ILI9486Rgb565 -> ILI9341 (lines 46, 244)
+- maybe lower the clock from 80MHz down to 10-20MHz for initial testing
+- back light pin 27 -> 21 (lines 119, 220)
+- xpt2046 sck 22 -> 25
+- xpt2046 mosi 26 -> 32
+
+## Touchscreen Driver
+
+It is a modified version of [tommy-gilligan/touchscreen](https://github.com/tommy-gilligan/touchscreen)
+
+TouchScreen instance no longer owns the LCD.  That wasn't being used in the
+crate and I believe it appears there to make way for a future calibration
+routine.  This really made it difficult to split the xpt2046 and ili9xxx
+instances into separate embassy tasks, which really assists in drawing on the
+screen.

Variants/3248S035C/Examples/1-Draw/bin/.cargo/config.toml

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+[target.xtensa-esp32-none-elf]
+runner = "espflash flash --monitor"
+
+[env]
+ESP_LOGLEVEL="INFO"
+
+[build]
+rustflags = [
+  "-C", "link-arg=-nostartfiles",
+]
+
+target = "xtensa-esp32-none-elf"
+
+[unstable]
+build-std = ["alloc", "core"]

Variants/3248S035C/Examples/1-Draw/bin/.gitignore

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+# generated by cargo
+/debug/
+/target
+
+# rustfmt backup files
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging info
+*.pdb
+
+.bacon-locations