Flash ESP32 chips directly from TinyGo

[aykevl]

This PR is a followup to #1289. It adds support for the custom image format used by the ESP32 and flashes it using esptool.py.
A future improvement may be to use one of the Go implementations of esptool to avoid the extra dependency.

Making this a draft for now until #1289 is merged (it should be rebased when it gets merged).

[deadprogram]

If you install via the Debian package, it names it esptool not esptool.py:

$ esptool.py version
esptool.py: command not found

$ esptool version
esptool.py v2.1
2.1

[aykevl]

If you install via the Debian package, it names it esptool not esptool.py:

Yes. I installed it with pip3. I also checked macOS and the Homebrew version also calls it esptool.py, so I think it's better to stick to that.
(And in any case, I'd like to do this natively in TinyGo eventually which means these external commands aren't necessary anymore).

[sago35]

I used apt install esptool on ubuntu 20.04 and it installed esptool instead of esptool.py.
I was able to do ln -s esptool esptool.py to tinygo flash.

[deadprogram]

@sago35 on my machine it was

sudo ln -s /usr/bin/esptool /usr/bin/esptool.py

[sago35]

@sago35 on my machine it was

sudo ln -s /usr/bin/esptool /usr/bin/esptool.py

me too.

[deadprogram]

Just tried this branch, received the following error:

$ tinygo flash -target esp32 examples/serial
error: ROM segments are non-contiguous: /tmp/tinygo829831007/main

Am I doing this correctly?

[deadprogram]

Wait, I think I have wrong version. Rebuilding...

[deadprogram]

$ tinygo flash -target esp32 -port /dev/ttyUSB0 examples/serial
esptool.py v2.1
Connecting....
Chip is ESP32D0WDQ6 (revision (unknown 0xa))
Enabling default SPI flash mode...
Configuring flash size...
Auto-detected Flash size: 4MB
Erasing flash...
Flash params set to 0x032f
Took 0.04s to erase flash block
Wrote 1024 bytes at 0x00001000 in 0.1 seconds (82.6 kbit/s)...
Hash of data verified.

Leaving...
Hard resetting...

Worked exactly as promised. Great job @aykevl this is getting more exciting by the hour!

Now merging, we need this!

[sago35]

my build log.

$ ./build/tinygo version
tinygo version 0.15.0-dev-5640eae linux/amd64 (using go version go1.14.4 and LLVM version 10.0.1)

$ ./build/tinygo build -o test.bin --target esp32 ./src/examples/serial/

$ ./build/tinygo build -o test.hex --target esp32 ./src/examples/serial/
error: ROM segments are non-contiguous: /tmp/tinygo391525433/main

$ ./build/tinygo flash --port /dev/ttyUSB0 --target esp32 ./src/examples/serial/
esptool.py v2.8
Serial port /dev/ttyUSB0
Connecting....
Chip is ESP32D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None
Crystal is 40MHz
MAC: a4:cf:12:56:2b:08
Enabling default SPI flash mode...
Configuring flash size...
Auto-detected Flash size: 4MB
Erasing flash...
Flash params set to 0x032f
Took 0.04s to erase flash block
Wrote 1024 bytes at 0x00001000 in 0.1 seconds (73.2 kbit/s)...
Hash of data verified.

Leaving...
Hard resetting via RTS pin...