This program allows displays to be used with MQTT equipped versions of the MMDVM. It takes the structured information, in JSON format, provided by the Host and Info programs, and converts it for use by displays. It currently supports the display types that were in the MMDVM-Host, but making the display handling external and simpler should allow for easier modifications and addition of new display types.
Environmental information that is not supplied by the Host is obtained via JSON created by the MMDVM-Info program. Some of this is supplied periodically automatically by the Info program, and some of it needs to be polled by the Display program since it is only needed once and will not change for the duration of running of the MMDVM system.
It builds on 32-bit and 64-bit Linux. It can control various displays, these are:
- HD44780 (sizes 2x16, 2x40, 4x16, 4x20)
- Support for HD44780 via 4 bit GPIO connection (user selectable pins)
- Adafruit 16x2 LCD+Keypad Kits (I2C)
- Connection via PCF8574 GPIO Extender (I2C)
- Nextion TFTs (all sizes, both Basic and Enhanced versions)
- OLED 128x64 (SSD1306)
- LCDproc
The Nextion displays can connect to the UART on the Raspberry Pi, or via a USB to TTL serial converter like the FT-232RL. It may also be connected to the UART output of the MMDVM modem (Arduino Due, STM32, Teensy).
The HD44780 displays are integrated with wiringPi for Raspberry Pi based platforms.
The OLED display needs an extra library see OLED.md
The LCDproc support enables the use of a multitude of other LCD screens. See the supported devices page on the LCDproc website for more info.
This software is licenced under the GPL v2 and is primarily intended for amateur and educational use.