MMDVM Blog @ http://mmdvm.blogspot.co.uk/
As quoted on github …
The MMDVM is intended to be an open-source Multi-Mode Digital Voice Modem, which utilities the power of an ARM processor and a simple analogue interface board. The Multi-Mode Digital Voice Modem is a combined hardware and software development of a modem to handle all amateur digital voice modes. Initially it will support D-Star and DMR, with System Fusion and P.25 coming later, as well as a built-in FM repeater controller. For all modes other than DMR and FM, the modem can be used in simplex or duplex mode, while for DMR and FM full duplex must be used.
The MMDVM is aimed at the Arduino Due, Teensy 3.1/3.2 and mbed platforms, the only requirement for the hardware is to be ARM Cortex-M3, M4, or M7 based, and access to raw interrupts and ADC and ADC ports as well as digital signalling ports.
For this reason the Raspberry Pi and similar single board computers are not being targeted as access to the raw I/O is mediated by the operating system kernel and does not provide the performance, nor does the hardware provide the necessary direct access to the I/O pins on the ARM processor. However such boards are very useful for hosting the interface of the modem to external networks such as ircDDB in the case of D-Star.
Cost is approx $40 plus $12 for MMDVM Board on it’s own from CLICK HERE TO VISIT SITE