mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-08-09 09:23:39 +00:00
Ayke van Laethem
0d692cfd0a
* Return len and errors in the Write method, to implement io.Writer. * Return a nil error in WriteByte, for compatibility with bufio.
45 lines
810 B
Go
45 lines
810 B
Go
// +build nrf51
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package ws2812
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// This file implements the WS2812 protocol for 16MHz Cortex-M0
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// microcontrollers.
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import (
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"device/arm"
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)
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// Send a single byte using the WS2812 protocol.
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func (d Device) WriteByte(c byte) error {
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// For the Cortex-M0 at 16MHz
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portSet, maskSet := d.Pin.PortMaskSet()
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portClear, maskClear := d.Pin.PortMaskClear()
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value := uint32(c) << 24
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arm.AsmFull(`
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send_bit:
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str {maskSet}, {portSet}
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lsls {value}, #1
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bcs.n skip_store
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str {maskClear}, {portClear}
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skip_store:
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nop
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nop
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nop
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nop
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nop
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nop
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str {maskClear}, {portClear}
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subs {i}, #1
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bne.n send_bit
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`, map[string]interface{}{
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"value": value,
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"i": 8,
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"maskSet": maskSet,
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"portSet": portSet,
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"maskClear": maskClear,
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"portClear": portClear,
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})
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return nil
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}
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