webkey

This project combines a web server and a USB keyboard to allow control over the boot sequence of a dual-boot machine.

The key sequence set in response to a POST command is deliberately limited to a sequence of F8's, 0-3 Down Arrows, followed by Enter. This enters the boot selection window, and blindly selects one of the items.

The code could be extended to allow more control over the key sequence being sent, but this is a fairly severe security hole. A malicious user could then send any sequence of keystrokes to your computer.

Tool chain

#rm -rf esp-idf ~/.espressif
git clone -bv4.3 --recursive https://github.com/espressif/esp-idf.git
cd esp-idf
git reset --hard 178b122
git submodule update --init --recursive
bash ./install.sh

Project configuration

source ../esp-idf/export.sh
idf.py set-target esp32s2
idf.py menuconfig
-> Webkey Configuration -> SSID/Password
-> Compont -> LWIP -> netif hostname

Build instructions

source ../esp-idf/export.sh
idf.py build
idf.py -p /dev/ttyUSB0 erase_flash
idf.py -p /dev/ttyUSB0 flash monitor

JTAG wiring

Wire Color	Saola Pin	WROOM Name	JTAG	JTAG	JTAG	WROOM Name	Saola Pin	Wire Color
Orange	J2‑1	3.3V	1‑VtRef		2‑NC
			3‑nTRST		4‑GND
Yellow	J3‑8	IO41	5‑TDI		6‑GND
Green	J3‑7	IO42	7‑TMS		8‑GND
Blue	J3‑10	IO39	9‑TCK	<-key	10‑GND
			11‑RTCK	<-key	13‑GND
Purple	J3‑9	IO40	13‑TDO		14‑GND
Grey	J3‑2	nRST	15‑RESET		16‑GND
			17‑DBGRQ		18‑GND
White	J2‑20	VDD	19‑VDD		20‑GND	GND	J2‑21	Black

OpenOCD use

Two iterations of init are required to power up the board prior to programming

openocd -f interface/jlink.cfg -f target/esp32s2.cfg -c"adapter_khz 1000; init; jlink targetpower on; exit"
openocd -f interface/jlink.cfg -f target/esp32s2.cfg -c"adapter_khz 1000; init; reset halt; program_esp build/webkey.bin 0x10000 verify exit"

Operation

To use programatically:

curl -X POST http://webkey/ctrl?key=b1
curl -X POST http://webkey/ctrl?key=b2
curl -X POST http://webkey/ctrl?key=b3
curl -X POST http://webkey/ctrl?key=b4

There is also a lovely web page at http://webkey/index.html that provides pushbuttons.