Electronics > Projects, Designs, and Technical Stuff
WIP: Reverse engineering the programming protocol for SiTime SiT8008
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lty1993:
Hello,

I got a SiTime Time Machine 2 and few blank SiT8008BI chips few days ago.

Since I cannot find any information about programming protocol online, I would like to reverse it myself.

It is been busy recently, the progress maybe slow.

==============================================================================
[Dec 8, 2018]

I managed to capture the programming waveform using a scope. (The model number I am programming to the blank device is SiT8008BI-21-XXN-8.000000)



The channel 1 is OE/ST/NC, channel 2 is OUT, channel 3 is VDD.

Here is hdf5 file I captured:
CH1.h5
CH2.h5
CH3.h5

==============================================================================
Rerouter:
It really looks like you have a serious amount of crosstalk.

at a glance it looks almost like CH3 is used as a chip select,
CH2 / CH1 as data pair, possibly SPI,

Any chance you can clean up your crosstalk issue, and zoom in a bit on the waveform to get an idea of how the 3 pairs are transistioning,

My best guess is the OE is used as MOSI, and the OUT as MISO,
lty1993:
It is really hard to probe the signal right without making a custom jig.



Anyway, I do not think the cross talk will affect much on interpreting the signal.

The OE is a three level signal as shown in next screenshot.



I posted the hdf5 files for each channel in the original post. You can use matlab, infiniium offline, or something similar to analyze them.
Rerouter:
The image is a much easier thing to analyse than 1GB of files that I cannot open without specialized software,

So far, CH1, is a clock, don't know what the positive bits are, but clearly 800,000 Hz

To me its exactly like SPI, maybe a 1 wire variation on it, looks like update on falling clock, and read on rising.
amyk:
I suspect that it's not just a frequency that's directly programmed into the device, but dividers, drive strengths, and other parameters that the programmer tunes in order to get the right frequency output.
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