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Ayke van Laethem
b3af3f594e
Previously, a new implementation had to be written for each processor
speed. This is tedious and error-prone, therefore I've rewritten all of
the assembly code using a tool that will calculate exactly how many NOP
instructions are required.
I've also switched from build tags to a switch statement over all
processor speeds.
All in all, this means that:
- Chips with a supported CPU performance will automatically be
supported (no build tags necessary).
- Adding a new chip is as easy as adding the MHz count to the
generator script and to the switch statement.
Right now this is only for the Cortex-M, but it's certainly feasible to
extend this to other architectures such as the AVR.
35 lines
867 B
Go
35 lines
867 B
Go
// +build cortexm
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package ws2812
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// This file implements the WS2812 protocol for various Cortex-M
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// microcontrollers. It is intended to work with various variants: M0, M0+, M3,
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// and M4. Because machine.CPUFrequency() is usually a constant, the value will
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// usually be constant-propagated and the switch below will be a direct
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// (inlinable function) - thus there is usually no code size penalty over build
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// tags per CPU speed.
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import (
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"machine"
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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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switch machine.CPUFrequency() {
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case 16_000_000: // 16MHz
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d.writeByte16(c)
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return nil
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case 48_000_000: // 48MHz
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d.writeByte48(c)
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return nil
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case 64_000_000: // 64MHz
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d.writeByte64(c)
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return nil
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case 120_000_000: // 120MHz
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d.writeByte120(c)
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return nil
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default:
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return errUnknownClockSpeed
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}
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}
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