Pulse sources:
ASCII ']', 0x5D - left trio.
ASCII 'u', 0x75 - right trio.
0xFF - single source in bottom left, which shows the 'frame' of the received pulses. Outside that frame are the start and stop bits, which this circuit doesn't use.
Note that the serial data goes down through each IC, but up from D of the lower one to 1 of the top one. Initially it went down all the way, but I changed it so you wouldn't have to read the output from bottom to top.
