Using OTA firmware loading is rather useful for IoT devices once they are “in the wild”. I adopted the precaution of using a hardware jumper to enable OTA because my devices spend most of their time in deep sleep to save power. The down-side of this is that I need to visit the device before each upload. Rather than wander about with a laptop, I thought that using my phone would be more convenient. Setting this up and using is fairly straight-forward but took a bit of thinking-through and desk research. So, for others interested in doing the same…
Termux
The power-house is Termux, which runs a (command-line only) linux environment on your phone. I installed the APK from f-droid, which seems to be common practice over Google Play Store.
Install python with:
pkg install python
Working with phone storage is not as simple as you might think; see the termux wiki. For example, I believe it is not possible to see the filesystem which you see inside Termux when the phone is connected to a PC for file transfer. My operating procedure is to copy firmware binaries into the phone’s Downloads folder and then to use the file manager on my phone to move it over to the Termux “home” as described on the wiki page.
The second issue is that working on the phone screen is a pain! I had previously installed scrcpy for use in demoing some software and this works a treat in making life easier. Keyboard joy! This just works. Read the documentation about enabling USB debugging in developer mode.
Doing the OTA
I’m using ESP8266’s so downloaded the espota.py script from the esp8266/Arduino github repository. You just need the one file. I expect the same procedure as I describe here would also work for ESP32 users with otatool.py.
What follows is based on having created a new directory in the termux “home”, placing espota.py in that directory and then creating one directory for each kind of device, which contains a small Bash script and the firmware binary file. I am also using PlatformIO inside VSCode.
Compiled firmware can be found in the project folder at: .pio\build\{env}, where {env} is the environment name in platformio.ini. Use the firmware.bin file (not the .elf file).
Create the bash script for ease of use (I call it upload.sh), substituting xxx.xxx.xxx.xxx with the device IP address:
#!/bin/bash python ../espota.py -d -i xxx.xxx.xxx.xxx -f firmware.bin
You can either use “nano” to edit these files inside Termux or move the .sh file between your phone and PC as noted above. Check the espota documentation for options to upload filesystem or if you’ve set up authentication.
Make it executable using:
chmod +x
This is simply run by using (in the appropriate directory):
./upload.sh
A nice modification if you have multiple devices of the same type is to change upload.sh to allow the IP address to be entered at run-time, in response to a prompt. All my devices are on the same subnet (192.168.1.x), so I only need enter the last component. The modified script is:
#!/bin/bash read -p "Last part of IP address: " python ../espota.py -d -i 192.168.1.$REPLY -f firmware.bin