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Allen Hill
33 lines
1.3 KiB
C
33 lines
1.3 KiB
C
// Copyright (C) 2015 Allen Hill <allenofthehills@gmail.com>
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// SPDX-License-Identifier: GPL-3.0-or-later
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#pragma once
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// Physical AVC-LAN bit-phase durations, in microseconds. These are protocol
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// facts (the bus spec), independent of any particular hardware. The active
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// target provides TICK_US — the wall-clock duration, in microseconds, of one
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// tick of whatever free-running timer it uses to measure/generate bus bits — so
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// each constant below resolves to a count of that target's ticks.
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//
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// Kept as #defines (not constexpr): no target is guaranteed to want these as a
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// specific integer width, so leave the type to the use site / target.
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#ifndef TICK_US
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#error \
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"target must define TICK_US (microseconds per bus-timer tick) before including timing.h"
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#endif
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// Measured at ±0.02 μs @ F_CPU=20MHz, TCB_CLKSEL=TCB_CLKSEL_CLKDIV1_gc
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#define AVCLAN_STARTBIT_LOGIC_0 (169.0 / TICK_US)
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#define AVCLAN_STARTBIT_LOGIC_1 (20.6 / TICK_US)
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#define AVCLAN_BIT1_LOGIC_0 (19.7 / TICK_US)
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#define AVCLAN_BIT1_LOGIC_1 (18.1 / TICK_US)
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#define AVCLAN_BIT0_LOGIC_0 (32.85 / TICK_US)
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#define AVCLAN_BIT0_LOGIC_1 (6.2 / TICK_US)
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#define AVCLAN_READBIT_THRESHOLD (26.0 / TICK_US)
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#define AVCLAN_BIT_LENGTH_MAX (39.1 / TICK_US)
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