Well it has been a while since my last post. I have been off for a couple of months due to rehabilitation on burnout and now very slowly trying to get back to life… but that is another story. But let me introduce you to my latest project…
After a successful reverse engineering of the CDM2 controller protocol and the full control of all functions I decided to redesign the faulty uProc board. Although my TAPE MCU replacement is working quite well it sometimes fails to indicate the end of the disc or a track when communicating the the CD MCU. The issue is based on different low/high levels and due to the fact that there is no real synchronisation between both MCUs. The clock of the tape MCU is working with 16MHz whilst the CD MCUs clock runs at 4MHz. Although using the same clock divided by 4 the communication is not as stable as I thought.
With a new design and by the use of the same 8-bit MCUs the clock can be synchronised and the feature range of the Sound Machine can be increased. In addition, instead of using input and output pins for the communication I use a serial protocol. This makes is more flexible and new commands can easily be added in future.
The idea is to have a plug and play replacement of the uProc board without any further changes to the system. To make my life easier a decided to replace tons of tinny transistors with logical gates optimised for the used MCU. The circuits for the relays and motors will stay untouched.
I haven’t really expected a working release of the board at the first try. Hell, I messed up several things very badly and had to design my own 4-input or-gate to use the PCB in any way. But now I am on a good way. Both MCUs are communicating with each other and the CD MCU is able to control the CDM2.
There’s only an issue with identifying the end of a track or CD. The track number from the CDM2 jumps between two tracks during the transition of a track or when navigating to a track which leads to wrong information.
And because I had some input pins left I added an Infrared Receiver – how great is this?
At the current state I am able to access all buttons and fully control the CDM2 with the remote control. Still have to fix the indication of the current track when jumping between programmed tracks. However, everything is looking very promising right now. The next step is to complete the tape electronics and check if the PCB is working and the circuits are correct.
I plan to release some videos with more information about the project…
