Capture digital data between microcontroller and led driver

[orgamisho]

Hello, I have a device which uses 3 7segment displays (4 digits each) controlled by a single led driver (TM1629A) which is controller by a microcontroller (MS51FB9AE).

I want to capture the communication between the 2 ICs, so I can decode it and read it from PC with USB cable.
The problem is that this task is slightly over my skills and I have no experience is such tasks.

I would be grateful if somebody give a hint how can I read and decode the digital signals or share a source where I can educate myself on this matter.
I have no idea what protocol is used in the communication.

The connection is as follows:

MS51FB9AE ---> TM1629A
1 (IC6 / T0 / PWM0_CH2 / ADC_CH4 / P0.5) ---> 7 (DIO) -> data
2 (UART0_TXD / ADC_CH3 / P0.6) ---> 8 (CLK) -> square clock wave
3 (UART0_RXD / ADC_CH2 / P0.7) ---> 9 (STB) -> at first seemed random noise, but reading the datasheet shows that it is set high only before instruction is given (my own understanding)

Now I struggle to read all bytes and their values on my pc. My problem is sending the raw data over a usb cable. I think I will be able to map it and write a software to decode it human language after that.
I have some experience using arduino, but not use if it can handle the clock speed of my circuit (according to datasheet the maximum is 1MHz, but haven't measured the actual).
Also I think it will be problem to wire the arduino to clock, data, and ground of my device circuit, but getting a 5v from usb, mixing both grounds.

I know about logic analyzers (which I dont have), but I think this would help only to observe the raw data by eye, not actually transefring the bytes' value to my pc.

Any suggestions, sources, etc would be appreciated!
Thanks!

[sam_sam_sam]

First of all you need get an understanding of how to program this micro controller because there are commands for different functions like displaying output information on RDX and TDX or SPI to be able to display them on either a LCD or LED display or computer screen

This micro controller does not seem to have a software lock but the micro controller that I am familiar with does have a boot loader and you can not retrieve the actual program lines as written but sometimes you reverse engineer to be able retrieve the program lines and redo it again to able to use it again

Here is where you can find the information needed

https://www.nuvoton.com/tool-and-sof...ogrammer-tool/

[truclacicr]

I think Bus Pirate might be what you need.

https://buspirate.com/

BTW, it would have been nice if you had linked to datasheets so that we didn't have to go looking for them.

http://nic.vajn.icu/PDF/opto/led-driver/TM1629A-en.pdf

[rogfanther]

Even a simple logic analyzer ( those cheap things from eastern origins ) will help you. And yes, their software ( Saleae, Sigrok, etc, will allow to save the data read to the computer for posterior processing ) .

[orgamisho]

Thank you all for your answers!

I managed somehow to read some bytes' values using an arduino as a bridge, but I didn't manage to distinguish any pattern in this data. I've made all the digits to display "1" (so this means only the segments are light up) and imported the data into excel, where I expected to see repeating pattern of bytes which value is the same (the value of "1") , but this did not happen.

I guess there is another data going on these pins, as it uses the RX and TX of the main IC. I've even ordered a cheap logic analyzer and I hope the manufacturer might have left some serial output which would be way easier to grab I think. But I will have to wait some for it to arrive before I can take any measurements.

Please correct me If am wrong in any of my actions ot assumptions.
I am still open for any other ideas ot advices as well!

Thank you!

[orgamisho]

Forgot to mention that I've tried reading the serial (again using an arduino as a bridge), but only got some strange characters. Tried multiple baudrates, without any different result. Hope the logic analyzer can help further with this

[rogfanther]

The chinese datasheet seems a bit more complete than the english one. But the communication seem to be in SPI, not the serial kind you would use baudrates with. Note on the datasheet, the pins of the UC can have many functions.
Look at the tables of commands for the led driver chip