Raspberry Pi Zero based handheld computer
It's basically a TI's USB 1s lithium battery charger to provide both buck and boost switching functions, to simplify the power design. The LCD is connected default SPI arrangement (SPI0), and keyboard is a USB HID device to provide user input.
This version has a working keyboard based on BBQ10 with RP2040 by running modified version firmware from https://github.com/solderparty/i2c_puppet
- BQ25616 needs OTG pin strobe to GND to initialized battery charge, as this pin has already pulled high, thus to boost battery voltage to 5V.
- USB traces are inverted, the symbol for RPI part has the pin number inverted, thus a PCB trace rework is required.
- BQ25616 can pull 7.5v from some high power USB charger, Pi Zero power IC will emit the magic smoke in minutes...
- Keyboard LED MOSFET gate pin is not connected.
- Add a USB hub chip to hook more RP2040 with B2B connector to house peripherals
- Add a nrf52840 to house Meshtastic device, with small OLED and GPS
- Replace BQ25616 and drop a DC/DC to PMID output, to prevent fry your Pi Zero, and you can hook a 4s model lithium battery pack
- Add a jog dial to keyboard chip, to implement tab/up arrow/down arrow key, as command line auto completion and history function
Refer to i2c-puppet building guide. As pico SDK is included in the repo, git pull will consume 900M traffic, you have been warned. After pulling the repo, replace files in app folder, and add new file in boards directory. cmake command is changed to:
cmake -DPICO_BOARD=bbq10kbd_breakout -DCMAKE_BUILD_TYPE=Debug ..