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Diffstat (limited to 'led/ws281x/README')
| -rw-r--r-- | led/ws281x/README | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/led/ws281x/README b/led/ws281x/README index 392acaa..b933a8e 100644 --- a/led/ws281x/README +++ b/led/ws281x/README @@ -8,31 +8,31 @@ roughly 100 frames per second. Details: - Koen Kooi's evil vendor tree: https://github.com/koenkooi/kernel - - PRU WS281x firmware: https://github.com/mranostay/ws28xx-lighting-pru + - PRU WS28xx firmware: https://github.com/mranostay/ws28xx-lighting-pru - WS2812B datasheet: http://www.adafruit.com/datasheets/WS2812.pdf WS2812B protocol overview ------------------------- -All values have +/- tolerance of 150 nanoseconds so the PRU firmware uses -slightly different timing value below to sync the high/low transitions. +All values have a +/- tolerance of 150 nanoseconds so the PRU firmware uses +the slightly different timing values below to sync the high/low transitions. Logic low -> high 0.40 uS -> low 0.85 uS (1.25 uS) Logic high -> high 0.80 uS -> low 0.45 uS (1.25 uS) Latch -> low 50 uS -Each LED receives and the stores the first 24-bits of GRB ordered data then +Each LED receives and then stores the first 24-bits of GRB ordered data then passes any more out the Data Output pin to the next LED in the chain. -This functions as a "reverse" shift register and allows the strip length not to -be defined in the protocol. +This functions as a "reverse" shift register and allows the strip length not +to be defined in the protocol. Logic analyzer setup -------------------- -The logic analzyer used was a Saleae Logic16 (at 5MHz). +The logic analyzer used was a Saleae Logic16 (at 5MHz): Probe WS2812B LED strip ----------------------------- @@ -51,3 +51,4 @@ The sigrok command line used was: sigrok-cli --driver saleae-logic16 --samples 10M --config samplerate=5mhz \ -p 0=UNI1,1=UNI2,2=UNI3,3=UNI4 -o ws281x_4ch_5mhz.sr + |