However two of them are connected to USB D+ and D- signal lines. However, if we take deeper look at its implementation, we will see that indeed, there are 6 digital pins. This means that we need 4 digital data lines in order to be able to communicate.Īt first sight, this means Digispark is more than enough in terms of available pins. And biggest differences are data lines, which are called DI – data in – and DO – data out – equivalents to MOSI and MISO in SPI. Then, there is CLK, which is simply a clock. So, there is CS – chip select with the difference that it is active high, unlike SPI’s chip select or slave select. We need the same four signals as with SPI, but their names are a bit different. Because, why not? □ Hardwareįrom the hardware point of view, it seems to be quite easy task. Enough of this, let’s read (and write, if you want) Microwire 93C56 EEPROM with Arduino sketch and Digispark board, via USB virtual serial port. At least for me, so I share my experience, just in case someone have similar problem. Obviously, the fact that this post appeared means, I was successful. I am not a big fan of Arduino, but I have few Digispark boards, so I decided to give it a try. Luckily for me, there is simple Arduino library, that bit-bangs the protocol. Unfortunately, I did not have any device that was confirmed successful and I did not want to experiment with low chance of success. It is however similar enough to SPI that some people were successful in talking to these EEPROMs on SPI bus. This means that flashrom is not an option here. In the meantime, I found that this thing talks Microwire protocol, which is quite similar, but not identical to SPI. So, to not break anything, I bought few similar memory chips from usual source. Fortunately I learned that chip it is connected to expect EEPROM from the 93C圆 series. It is quite obscure, as Google did not return anything useful (beside Taobao auctions). What I had to do, was to read contents of EEPROM, that I found on board, I am analyzing. For now I want to present a tool that I made while working on this big thing (as a side note, it’s not the first one, cc-factory was also created for that purpose). Of course this would be something almost unique, if finished. I hope, I will be able to present something on that in future. For some time already, I am working on a big reverse engineering topic.
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