I'm working on a project that involves the optical sensor from a mouse. I've got the original control PCB (still populated, save for the optical sensor itself), and I've got the optical sensor on my custom PCB, supposed to be controlled by an nrf51822. I've wired the clock + data pins (it's a two-wire interface) to both boards, driven by the original control board (I've set my clock and data pins as inputs with no pulling resistors).
I'm trying to capture traffic to determine what signals are being sent, but I'm not having a lot of luck - I suspect my clock rate is too low. As quickly as possible (just inside a
while true loop), I'm scanning my clock pin and my data pin, then printing them both to my console output over UART at 1M baud. Running this loop empty for 5 seconds results in ~4000 cycles, meaning I'm getting >1ms run time for each loop - which I think is my main problem.
As it is, I capture (in roughly 700 scans) 100 groups of alternating "clock 1 and data 1" and "clock 0 and data 0" - each group is 4-9 items (that is, 4-9 "1s" on both, followed by 4-9 "0s" on both). Then, about 400 scans later (~0.5 seconds) I get the same thing, but 54 groups. At that point I stopped scanning.
Is there any way to either: A) Speed up my scan cycle so I can capture the traffic more accurately? or B) Decode what I already have (doubtful)?
Do I need to consider an alternate route? I haven't found any access to an oscilloscope, which is... unfortunate.
I'd appreciate any advice. Thanks.