Things now slow down a bit. I expected much more rapid progress with the micro. There were some obstacles that should not have been obstacles: The default reset value for an output pin is analogue input (took a good 3-4 hours to find out). My new USB/TTL UART doesn’t have the CTS/RTS pins wired internally to the power supply, so I can’t bypass flow control that easily (2-3 hours). The battery lasts around 5 hours in the oscilloscope (2×1 hour break). The poor thing sometimes re-sets because of interference. This will be solved as soon as I get rid of all the earth loops caused by the programmer, the UART and the oscilloscope and power supply.
Good news is that current-mode PWM powered LEDs are very closely linear. I managed to find my components in the morning (well, the components found me, actually…)