Microdrive data line format

[kladogen]

Hi and thanks for the help!

Yellow is track1, green track2.

I prepared a few screen shots from the oscilloscope:
1. a few sectors
2. one sector
3. a header
4. a header's data in more detail
5. bit_timing : shows the bit timing in 1μs scale

The power source is from the QL 9V pin through a traco power tsr1-2450

Any ideas welcome! The data send on the tracks is produced by porting gertk's code to arduino nano show it should be fundamentally correct (I hope).

Regards

Antonis

[kladogen]

Here you can see the test board and more details of the data on the tracks.

[martyn_hill]

Hi Antonis!

Those traces look good to me from a timing and voltage level point of view.

My only thoughts right now would be:

a. Double-check that RAW1 and RAW2 data lines really are wired as expected and not reversed. I'm sure you have checked many times, but its easy to get them switched by mistake - RAW1 always leads RAW2 on the QL. unlike on the Spectrum where DATA2 leads DATA1...

b. Those over/under shoots (under-damped) beyond 5v/0v might be upsetting the ZX8302 - perhaps try adding some extra capacitance to RAW1/2 to dampen the transition artefacts.

if I think of anyghing else, Ill write again.

[kladogen]

Hi,

I just checked again my connections. I have

TRACK1 data-> Nano A4-> 2.2K Resistor -> EDGE CONNECTOR TOP.1
TRACK2 data-> Nano A0-> 2.2K Resistor -> EDGE CONNECTOR BOTTOM.1

which I believe is correct. After the problems I had I copied this design from oqtadrive but it did not seem to help.

I will also try to add some small capacitors to the track lines in order to smooth them up.

Regards

Antony