The FT8900 doesn't have an external interface option, this makes it difficult to interface with other devices. The solution to this reverse engineer the remote head protocol and build a control unit that interfaces this to the radio.
After a bit of a Hiatus on this project I am back with some progress.
The PCB's from the previous log have a few issues which I missed before I sent them off. The order of the pins on the 6P6C connectors for the head and body are the wrong way round, I recrimped the link cables to fix this. In addition the connectors for the head and body are switched so they are in the wrong place on the board. luckily both of these where fixable without too much trouble, but I will need to do another revision at a later date.
I have attempted to 3d print the case a couple of times and seem to have got the right dimensions but the pieces have warped meaning that the case halves don't fit together properly.
With the hardware issues identified it was onto writing some firmware.
So far on the firmware I have added the ability to read the state of elements on the LCD and the state of controls being send back to the main unit. In addition it can also decode the text being displayed on the LCD and convert it back into human readable strings. The next step will be to write the code that allows for the streams between the head and body to be manipulated as they pass through.
It has been a while since I last updated this but the project has been making some progress.
Some of the more interesting parts that have been done.
Created a schematic for the Interface with the radio. The unit uses an ATmega2560 as the main processor as three serial ports are required (one for the base unit, one for the head and one for the USB interface). The USB interface is provided by an FTDI FT232RL with an isolation bridge between it and the rest of interface module.
A case has been deigned for the module, the case fits in between the front plate and the main unit so as to blend in when the radio is in one piece, there is still a bit of refinement to do so everything fits together properly but it is mostly there now. It is shown below rendered in transparent plastic so you can see the internal structure and PCB. It will be 3d printed in black for the actual unit.
PCB's for the interface module have been designed and created, haven't managed to solder any up yet as i'm still waiting for parts to arrive.
Once the bits arrive Ill be able to get one soldered up and will start writing some code to make it do stuff.