Some initial bus sniffing of the communication, VERY preliminary results:
Control connector, 8 pins, FS1
1 - PA0 = Some kind of -POWER_GOOD, is connected to a transistor on SP with the base at 3.3V
2 - GND
3 - PA1 = Not found yet
4 - PB11 = BitX FP -> SB
5 - PB12 = BitX FP -> SB
6 - PB13 = CLOCK, 18MHz !!!, 32 clocks/transfer.
7 - PB14 = BitX FP -> SB
8 - PB15 = BitX FP -> SB
So, it seem that most of statements up until now regarding the communication protocols were false, including some assumptions of mine.
The clock is a respectable 18MHz, the data bus seem to nibble oriented, 4bits / clock, 32 nibbles or 16 bytes or 4 x 32bits values.
No matter how small is the change ( for example just moving the encoder one position, there is a minimum of 16 transfers, or 64 x 32bit values.
So I have the feeling that each time the SB it's fully programmed, no matter how small it's the change !!!
Also barring pin 3 (PA1) doing any direction switch, the data transfer seem to be strictly from FP to SB, I have no idea how the stored waveforms are read back, if they are read.
Have a look on the pictures attached, made with my crappy TBS1104, there are 3 bits and the clock is on the yellow trace.
TODO:
- See what is happening with pin 3, it really the transfer uni-directional ?
- See which bit is which ?
- Connect a proper LA (if it will ever arrive) and get a number of transfers
- Decode the protocol and how the calibration constants are loaded.
- The waveforms are actually stored in the SB flash and the FP just tell the SB which one to load ?
Happy New Year !!!