mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-08-11 02:13:42 +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.
43 lines
1.2 KiB
Go
43 lines
1.2 KiB
Go
// +build arduino
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package ws2812
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// This file implements the WS2812 protocol for 16MHz AVR microcontrollers.
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import (
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"device/avr"
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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 AVR at 16MHz
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portSet, maskSet := d.Pin.PortMaskSet()
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portClear, maskClear := d.Pin.PortMaskClear()
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avr.AsmFull(`
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send_bit:
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st {portSet}, {maskSet} ; [2] set output high
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lsl {value} ; [1] shift off the next bit, store it in C
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brcs skip_store ; [1/2] branch if this bit is high (long pulse)
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st {portClear}, {maskClear} ; [2] set output low (short pulse)
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skip_store:
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nop ; [6] wait before changing the output again
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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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st {portClear}, {maskClear} ; [2] set output low (end of pulse)
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subi {i}, 1 ; [1] subtract one (for the loop)
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brne send_bit ; [1/2] send the next bit, if not at the end of the loop
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`, map[string]interface{}{
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"value": c,
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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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