- 1800Hz, 16-bit PWM (12-bit + 4 bits dithering)
- 3-channels, almost evenly spaced phase offsets
- inverse polarity compared to WS2811 (pin high = LED on)
- UART based signalling, 38400 baud, 16 bit values, (2x 8bit uart frame/channel, little endian)
- end-of-frame is determined using a reset delay (between 1-2msec)
- no output line, led index is hard-coded in the firmware
- tested on PFS154 & PMS150C
$ ./write.sh 0 # use the first 6 bytes as pixel data
$ ./write.sh 1 # use bytes 6..11 as pixel data
$ ./read_address.sh
Address: 0
Even on one-time programmable chips, a limited number of address changes if possible:
$ ./change_address.sh 4 # this is the fourth chip in the LED strip
OTP parts like PMS150C start out with a ROM with all ones, bits can only be flipped once, from 1 to 0.
The following scheme makes it possible to update the chip's address many times:
The code reads (13 or 14 bit) opcodes at the end of the code section. opcodes where the high bits are set to 0 are skipped. The first opcode with non-zero high bits contains the address in its low byte.