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ws2812: fix timings for the nrf51

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The timings needed to be changed slightly for ws2811 chips which are
slightly slower.
This commit is contained in:
Ayke van Laethem
2019-08-19 00:33:07 +02:00
committed by Ron Evans
parent c91888a099
commit d80f619c9f
1 changed files with 6 additions and 4 deletions
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ws2812/ws2812_m0_16m.go
+6 -4
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@@ -17,14 +17,16 @@ func (d Device) WriteByte(c byte) error {
// See: // See:
// https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/ // https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/
// T0H: 4 cycles or 250ns // Note: timings have been increased slightly to also support ws2811 LEDs.
// T0L: 14 cycles or 875ns -> together 18 cycles or 1125ns // T0H: 5 cycles or 312.5ns
// T1H: 10 cycles or 625ns // T0L: 14 cycles or 875.0ns -> together 19 cycles or 1187.5ns
// T1H: 8 cycles or 500ns -> together 18 cycles or 1125ns // T1H: 11 cycles or 687.5ns
// T1H: 8 cycles or 500.0ns -> together 19 cycles or 1187.5ns
value := uint32(c) << 24 value := uint32(c) << 24
arm.AsmFull(` arm.AsmFull(`
send_bit: send_bit:
str {maskSet}, {portSet} @ [2] T0H and T0L start here str {maskSet}, {portSet} @ [2] T0H and T0L start here
nop @ [1]
lsls {value}, #1 @ [1] lsls {value}, #1 @ [1]
bcs.n skip_store @ [1/3] bcs.n skip_store @ [1/3]
str {maskClear}, {portClear} @ [2] T0H -> T0L transition str {maskClear}, {portClear} @ [2] T0H -> T0L transition