mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-08-12 02:43:42 +00:00
Ayke van Laethem
65f8299153
This patch adds support for the ESP8266 chip by adding support for 80MHz operation. This should also work when the ESP32 is changed to 80MHz, but I didn't test it (as there is not currently a way to do that). Verified on a NodeMCU dev board with an ESP8266.
347 lines
5.5 KiB
Go
347 lines
5.5 KiB
Go
// +build xtensa
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package ws2812
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import (
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"device"
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"errors"
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"machine"
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"unsafe"
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)
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var errUnknownClockSpeed = errors.New("ws2812: unknown CPU clock speed")
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func (d Device) WriteByte(c byte) error {
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portSet, maskSet := d.Pin.PortMaskSet()
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portClear, maskClear := d.Pin.PortMaskClear()
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switch machine.CPUFrequency() {
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case 160e6: // 160MHz
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// See:
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// https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/
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// Because I do not know the exact instruction timings, I'm going to
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// assume that every instruction executes in one cycle. Branches and
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// load/stores will probably be slower than that, but as long as all
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// timings are only increased a little bit this should not be a problem
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// (see above post).
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// T0H: 40 cycles or 333.3ns
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// T0L: 131 cycles or 1091.7ns
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// +: 171 cycles or 1425.0ns
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// T1H: 95 cycles or 791.7ns
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// T1L: 75 cycles or 625.0ns
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// +: 170 cycles or 1416.7ns
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// Some documentation:
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// http://cholla.mmto.org/esp8266/xtensa.html
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// https://0x04.net/~mwk/doc/xtensa.pdf
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device.AsmFull(`
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1: // send_bit
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s32i {maskSet}, {portSet}, 0 // [1] T0H and T1H start here
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nop // [37]
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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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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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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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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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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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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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slli {value}, {value}, 1 // [1] shift {value} to the left by 1
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bbsi {value}, 8, 2f // [1] branch to skip_store if bit 8 is set
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s32i {maskClear}, {portClear}, 0 // [1] T0H -> T0L transition
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2: // skip_store
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nop // [55]
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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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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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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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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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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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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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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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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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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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s32i {maskClear}, {portClear}, 0 // [1] T1H -> T1L transition
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nop // [72]
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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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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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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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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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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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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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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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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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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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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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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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nop
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nop
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nop
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nop
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addi {i}, {i}, -1 // [1]
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bnez {i}, 1b // [1] send_bit, T1H and T1L end here
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// Restore original values after modifying them in the inline
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// assembly. Not doing that would result in undefined behavior as
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// the compiler doesn't know we're modifying these values.
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movi.n {i}, 8
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slli {value}, {value}, 8
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`, map[string]interface{}{
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// Note: casting pointers to uintptr here because of what might be
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// an Xtensa backend bug with inline assembly.
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"value": uint32(c),
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"i": 8,
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"maskSet": maskSet,
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"portSet": uintptr(unsafe.Pointer(portSet)),
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"maskClear": maskClear,
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"portClear": uintptr(unsafe.Pointer(portClear)),
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})
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return nil
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case 80e6: // 80MHz
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// See docs for 160MHz.
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// T0H: 21 cycles or 262.5ns
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// T0L: 67 cycles or 837.5ns
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// +: 88 cycles or 1100.0ns
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// T1H: 47 cycles or 587.5ns
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// T1L: 39 cycles or 487.5ns
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// +: 86 cycles or 1075.0ns
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device.AsmFull(`
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1: // send_bit
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s32i {maskSet}, {portSet}, 0 // [1] T0H and T1H start here
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nop // [18]
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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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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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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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slli {value}, {value}, 1 // [1] shift {value} to the left by 1
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bbsi {value}, 8, 2f // [1] branch to skip_store if bit 8 is set
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s32i {maskClear}, {portClear}, 0 // [1] T0H -> T0L transition
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2: // skip_store
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nop // [27]
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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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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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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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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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nop
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nop
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s32i {maskClear}, {portClear}, 0 // [1] T1H -> T1L transition
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nop // [36]
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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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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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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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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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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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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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addi {i}, {i}, -1 // [1]
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bnez {i}, 1b // [1] send_bit, T1H and T1L end here
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// Restore original values after modifying them in the inline
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// assembly. Not doing that would result in undefined behavior as
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// the compiler doesn't know we're modifying these values.
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movi.n {i}, 8
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slli {value}, {value}, 8
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`, map[string]interface{}{
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// Note: casting pointers to uintptr here because of what might be
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// an Xtensa backend bug with inline assembly.
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"value": uint32(c),
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"i": 8,
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"maskSet": maskSet,
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"portSet": uintptr(unsafe.Pointer(portSet)),
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"maskClear": maskClear,
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"portClear": uintptr(unsafe.Pointer(portClear)),
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})
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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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