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Added support for 125MHz to WS2812 for RP2040
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@bgould
bgould committed Feb 14, 2022
1 parent 10bd48c commit b4eb406
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Showing 3 changed files with 303 additions and 1 deletion.
299 changes: 299 additions & 0 deletions ws2812/ws2812-asm_cortexm.go
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Original file line number Diff line number Diff line change
Expand Up @@ -652,6 +652,305 @@ func (d Device) writeByte120(c byte) {
interrupt.Restore(mask)
}

func (d Device) writeByte125(c byte) {
portSet, maskSet := d.Pin.PortMaskSet()
portClear, maskClear := d.Pin.PortMaskClear()

// Timings:
// T0H: 44 - 46 cycles or 352.0ns - 368.0ns
// T1H: 132 - 134 cycles or 1056.0ns - 1072.0ns
// TLD: 144 - cycles or 1152.0ns -
mask := interrupt.Disable()
value := uint32(c) << 24
device.AsmFull(`
1: @ send_bit
str {maskSet}, {portSet} @ [2] T0H and T0L start here
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lsls {value}, #1 @ [1]
bcs.n 2f @ [1/3] skip_store
str {maskClear}, {portClear} @ [2] T0H -> T0L transition
2: @ skip_store
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str {maskClear}, {portClear} @ [2] T1H -> T1L transition
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subs {i}, #1 @ [1]
bne.n 1b @ [1/3] send_bit
`, map[string]interface{}{
"value": value,
"i": 8,
"maskSet": maskSet,
"portSet": portSet,
"maskClear": maskClear,
"portClear": portClear,
})
interrupt.Restore(mask)
}

func (d Device) writeByte168(c byte) {
portSet, maskSet := d.Pin.PortMaskSet()
portClear, maskClear := d.Pin.PortMaskClear()
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2 changes: 1 addition & 1 deletion ws2812/ws2812.go
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
// Package ws2812 implements a driver for WS2812 and SK6812 RGB LED strips.
package ws2812 // import "tinygo.org/x/drivers/ws2812"

//go:generate go run gen-ws2812.go -arch=cortexm 16 48 64 120 168
//go:generate go run gen-ws2812.go -arch=cortexm 16 48 64 120 125 168
//go:generate go run gen-ws2812.go -arch=tinygoriscv 160 320

import (
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3 changes: 3 additions & 0 deletions ws2812/ws2812_cortexm.go
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,9 @@ func (d Device) WriteByte(c byte) error {
case 120_000_000: // 120MHz
d.writeByte120(c)
return nil
case 125_000_000: // 125MHz
d.writeByte125(c)
return nil
case 168_000_000: // 168MHz, e.g. stm32f405
d.writeByte168(c)
return nil
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