i was sending pixel data out from an Arduino (ESP32 really but using Arduino IDE) to a bunch of shift registers that seemed to be 74x595 (but couldnt know for sure) to resurrect an LED display for a local art project, and reading the data coming back out from the last register let me know I was at least getting back what I was putting in, which helped me troubleshoot a few wire length and speed/stability issues
i was sending pixel data out from an Arduino (ESP32 really but using Arduino IDE) to a bunch of shift registers that seemed to be 74x595 (but couldnt know for sure) to resurrect an LED display for a local art project, and reading the data coming back out from the last register let me know I was at least getting back what I was putting in, which helped me troubleshoot a few wire length and speed/stability issues
to get started with electronics and hardware in general, I wrote a short tutorial: https://news.ycombinator.com/item?id=35116705