Lightning Piggy

Bitcoin Lightning piggybank using LNBits (for LNURLp) running on TTGO LilyGo ePaper hardware with ESP32 microcontroller.

See https://www.lightningpiggy.com/ and https://makers.bolt.fun/project/lightningpiggy

Main Source code

The source code in Main/Main.ino works on both the TTGO LilyGo T5 ePaper 2.13 inch DEPG0213BN display and the (discontinued and more expensive) TTGO LilyGo T5 ePaper 2.66 inch DEPG0266BN display boards.

Tested with:

• Arduino IDE version 1.8.13
• ESP32 Board Support version 2.0.14
• Preferences -> Compiler warnings: Default
• Tools -> Board -> ESP32 Arduino -> ESP32 Dev Module

Where:

• Tools -> Upload Speed: 921600
• Tools -> CPU Frequency: 240Mhz
• Tools -> Flash Frequency: 80Mhz
• Tools -> Flash Mode: QIO
• Tools -> Flash Size: 4MB (32Mb)
• Tools -> Partition Scheme: Default 4MB with spiffs (1.2MB APP, 1.5MB SPIFFS)
• Tools -> Core Debug Level: Warn
• Tools -> PSRAM: Disabled
• Tools -> Port: /dev/ttyACM0

Make sure the Arduino IDE has permissions to access the serial port:

sudo chmod -f 777 /dev/ttyACM* /dev/ttyUSB*

On the lnbits webpage:

• activate the LNURLp extension
• click on the LNURLp extension
• click "NEW PAY LINK"
• untick "fixed amount"
• set minimum amount: 1
• set maximum amount: 100000000
• set currency to "satoshis"
• click "Advanced options"
• set "Comment maximum characters" to 128
• set "Webhook URL" to https://p.lightningpiggy.com/ (optional, for anonymous usage metrics)
• set a "Success message", like: Thanks for sending sats to my piggy

Known issues:

• There's an issue with the 2.13 inch GDEM0213B74 display, somehow the display becomes blank after updateWindow() calls.

How to install

To install Lightning Piggy from the code base (rather than just using the latest release and using the web installer at https://lightningpiggy.github.io):

• Connect the device via USB
• Open /Main/Main.ino using Arduino Studio.
• Update values in config.h
• Copy the libraries used from C:...\lightning-piggy\Splash\libraries\ to your Arduino libraries folder (usually C:\Users\YourUsername\Documents\Arduino\libraries).
• Upload using Sketch > Upload.

To install the temporary Lightning Piggy Splash (used for shipping):

• Connect the device via USB
• Open /Splash/Splash.ino using Arduino Studio.
• Upload using Sketch > Upload.

How to release

To make a new release available on the web installer:

• Open /Main/Main.ino using Arduino Studio.
• Update version number in Constants.h
• Make sure config.h has no unintended development changes (cp Main/config.h /tmp; git checkout Main/config.h)
• Update CHANGELOG.md
• Copy the libraries used from C:...\lightning-piggy\Splash\libraries\ to your Arduino libraries folder (usually C:\Users\YourUsername\Documents\Arduino\libraries).
• Compile the project using Sketch > Compile.
• Copy /tmp/build_*/Main.ino.bin to firmware/ttgo_lilygo_2.13_and_2.66_inch_epaper_4.x/
• Update the version number in lightningpiggy.github.io/manifests/manifest_ttgo_lilygo_2.13_and_2.66_inch_epaper_4.x.json
• Revert back to default code with custom config (cp /tmp/config.h Main/config.h)