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test_bit_timing.py
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442 lines (395 loc) · 13.3 KB
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#!/usr/bin/env python
import struct
import pytest
import can
from can.interfaces.pcan.pcan import PCAN_BITRATES
def test_sja1000():
"""Test some values obtained using other bit timing calculators."""
timing = can.BitTiming(
f_clock=8_000_000, brp=4, tseg1=11, tseg2=4, sjw=2, nof_samples=3
)
assert timing.f_clock == 8_000_000
assert timing.bitrate == 125_000
assert timing.brp == 4
assert timing.nbt == 16
assert timing.tseg1 == 11
assert timing.tseg2 == 4
assert timing.sjw == 2
assert timing.nof_samples == 3
assert timing.sample_point == 75
assert timing.btr0 == 0x43
assert timing.btr1 == 0xBA
timing = can.BitTiming(f_clock=8_000_000, brp=1, tseg1=13, tseg2=2, sjw=1)
assert timing.f_clock == 8_000_000
assert timing.bitrate == 500_000
assert timing.brp == 1
assert timing.nbt == 16
assert timing.tseg1 == 13
assert timing.tseg2 == 2
assert timing.sjw == 1
assert timing.nof_samples == 1
assert timing.sample_point == 87.5
assert timing.btr0 == 0x00
assert timing.btr1 == 0x1C
timing = can.BitTiming(f_clock=8_000_000, brp=1, tseg1=5, tseg2=2, sjw=1)
assert timing.f_clock == 8_000_000
assert timing.bitrate == 1_000_000
assert timing.brp == 1
assert timing.nbt == 8
assert timing.tseg1 == 5
assert timing.tseg2 == 2
assert timing.sjw == 1
assert timing.nof_samples == 1
assert timing.sample_point == 75
assert timing.btr0 == 0x00
assert timing.btr1 == 0x14
def test_from_bitrate_and_segments():
timing = can.BitTiming.from_bitrate_and_segments(
f_clock=8_000_000, bitrate=125_000, tseg1=11, tseg2=4, sjw=2, nof_samples=3
)
assert timing.f_clock == 8_000_000
assert timing.bitrate == 125_000
assert timing.brp == 4
assert timing.nbt == 16
assert timing.tseg1 == 11
assert timing.tseg2 == 4
assert timing.sjw == 2
assert timing.nof_samples == 3
assert timing.sample_point == 75
assert timing.btr0 == 0x43
assert timing.btr1 == 0xBA
timing = can.BitTiming.from_bitrate_and_segments(
f_clock=8_000_000, bitrate=500_000, tseg1=13, tseg2=2, sjw=1
)
assert timing.f_clock == 8_000_000
assert timing.bitrate == 500_000
assert timing.brp == 1
assert timing.nbt == 16
assert timing.tseg1 == 13
assert timing.tseg2 == 2
assert timing.sjw == 1
assert timing.nof_samples == 1
assert timing.sample_point == 87.5
assert timing.btr0 == 0x00
assert timing.btr1 == 0x1C
timing = can.BitTiming.from_bitrate_and_segments(
f_clock=8_000_000, bitrate=1_000_000, tseg1=5, tseg2=2, sjw=1
)
assert timing.f_clock == 8_000_000
assert timing.bitrate == 1_000_000
assert timing.brp == 1
assert timing.nbt == 8
assert timing.tseg1 == 5
assert timing.tseg2 == 2
assert timing.sjw == 1
assert timing.nof_samples == 1
assert timing.sample_point == 75
assert timing.btr0 == 0x00
assert timing.btr1 == 0x14
timing = can.BitTimingFd.from_bitrate_and_segments(
f_clock=80_000_000,
nom_bitrate=500_000,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_bitrate=2_000_000,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
)
assert timing.f_clock == 80_000_000
assert timing.nom_bitrate == 500_000
assert timing.nom_brp == 1
assert timing.nbt == 160
assert timing.nom_tseg1 == 119
assert timing.nom_tseg2 == 40
assert timing.nom_sjw == 40
assert timing.nom_sample_point == 75
assert timing.f_clock == 80_000_000
assert timing.data_bitrate == 2_000_000
assert timing.data_brp == 1
assert timing.dbt == 40
assert timing.data_tseg1 == 29
assert timing.data_tseg2 == 10
assert timing.data_sjw == 10
assert timing.data_sample_point == 75
def test_can_fd():
timing = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=1,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_brp=1,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
)
assert timing.f_clock == 80_000_000
assert timing.nom_bitrate == 500_000
assert timing.nom_brp == 1
assert timing.nbt == 160
assert timing.nom_tseg1 == 119
assert timing.nom_tseg2 == 40
assert timing.nom_sjw == 40
assert timing.nom_sample_point == 75
assert timing.f_clock == 80_000_000
assert timing.data_bitrate == 2_000_000
assert timing.data_brp == 1
assert timing.dbt == 40
assert timing.data_tseg1 == 29
assert timing.data_tseg2 == 10
assert timing.data_sjw == 10
assert timing.data_sample_point == 75
def test_from_btr():
timing = can.BitTiming.from_registers(f_clock=8_000_000, btr0=0x00, btr1=0x14)
assert timing.bitrate == 1_000_000
assert timing.brp == 1
assert timing.nbt == 8
assert timing.tseg1 == 5
assert timing.tseg2 == 2
assert timing.sjw == 1
assert timing.sample_point == 75
assert timing.btr0 == 0x00
assert timing.btr1 == 0x14
def test_btr_persistence():
f_clock = 8_000_000
for btr0btr1 in PCAN_BITRATES.values():
btr1, btr0 = struct.unpack("BB", btr0btr1)
t = can.BitTiming.from_registers(f_clock, btr0, btr1)
assert t.btr0 == btr0
assert t.btr1 == btr1
def test_from_sample_point():
timing = can.BitTiming.from_sample_point(
f_clock=16_000_000,
bitrate=500_000,
sample_point=69.0,
)
assert timing.f_clock == 16_000_000
assert timing.bitrate == 500_000
assert 68 < timing.sample_point < 70
fd_timing = can.BitTimingFd.from_sample_point(
f_clock=80_000_000,
nom_bitrate=1_000_000,
nom_sample_point=75.0,
data_bitrate=8_000_000,
data_sample_point=70.0,
)
assert fd_timing.f_clock == 80_000_000
assert fd_timing.nom_bitrate == 1_000_000
assert 74 < fd_timing.nom_sample_point < 76
assert fd_timing.data_bitrate == 8_000_000
assert 69 < fd_timing.data_sample_point < 71
# check that there is a solution for every sample point
for sp in range(50, 100):
can.BitTiming.from_sample_point(
f_clock=16_000_000, bitrate=500_000, sample_point=sp
)
# check that there is a solution for every sample point
for nsp in range(50, 100):
for dsp in range(50, 100):
can.BitTimingFd.from_sample_point(
f_clock=80_000_000,
nom_bitrate=500_000,
nom_sample_point=nsp,
data_bitrate=2_000_000,
data_sample_point=dsp,
)
def test_equality():
t1 = can.BitTiming.from_registers(f_clock=8_000_000, btr0=0x00, btr1=0x14)
t2 = can.BitTiming(f_clock=8_000_000, brp=1, tseg1=5, tseg2=2, sjw=1, nof_samples=1)
t3 = can.BitTiming(
f_clock=16_000_000, brp=2, tseg1=5, tseg2=2, sjw=1, nof_samples=1
)
assert t1 == t2
assert t1 != t3
assert t2 != t3
assert t1 != 10
t4 = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=1,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_brp=1,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
)
t5 = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=1,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_brp=1,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
)
t6 = can.BitTimingFd.from_sample_point(
f_clock=80_000_000,
nom_bitrate=1_000_000,
nom_sample_point=75.0,
data_bitrate=8_000_000,
data_sample_point=70.0,
)
assert t4 == t5
assert t4 != t6
assert t4 != t1
def test_string_representation():
timing = can.BitTiming(f_clock=8_000_000, brp=1, tseg1=5, tseg2=2, sjw=1)
assert str(timing) == (
"BR: 1_000_000 bit/s, SP: 75.00%, BRP: 1, TSEG1: 5, TSEG2: 2, SJW: 1, "
"BTR: 0014h, CLK: 8MHz"
)
fd_timing = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=1,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_brp=1,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
)
assert str(fd_timing) == (
"NBR: 500_000 bit/s, NSP: 75.00%, NBRP: 1, NTSEG1: 119, NTSEG2: 40, NSJW: 40, "
"DBR: 2_000_000 bit/s, DSP: 75.00%, DBRP: 1, DTSEG1: 29, DTSEG2: 10, DSJW: 10, "
"CLK: 80MHz"
)
def test_repr():
timing = can.BitTiming(f_clock=8_000_000, brp=1, tseg1=5, tseg2=2, sjw=1)
assert repr(timing) == (
"can.BitTiming(f_clock=8000000, brp=1, tseg1=5, tseg2=2, sjw=1, nof_samples=1)"
)
fd_timing = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=1,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_brp=1,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
)
assert repr(fd_timing) == (
"can.BitTimingFd(f_clock=80000000, nom_brp=1, nom_tseg1=119, nom_tseg2=40, "
"nom_sjw=40, data_brp=1, data_tseg1=29, data_tseg2=10, data_sjw=10)"
)
def test_hash():
_timings = {
can.BitTiming(f_clock=8_000_000, brp=1, tseg1=5, tseg2=2, sjw=1, nof_samples=1),
can.BitTimingFd(
f_clock=80_000_000,
nom_brp=1,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_brp=1,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
),
}
def test_mapping():
timing = can.BitTiming(f_clock=8_000_000, brp=1, tseg1=5, tseg2=2, sjw=1)
timing_dict = dict(timing)
assert timing_dict["f_clock"] == timing["f_clock"]
assert timing_dict["brp"] == timing["brp"]
assert timing_dict["tseg1"] == timing["tseg1"]
assert timing_dict["tseg2"] == timing["tseg2"]
assert timing_dict["sjw"] == timing["sjw"]
assert timing == can.BitTiming(**timing_dict)
fd_timing = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=1,
nom_tseg1=119,
nom_tseg2=40,
nom_sjw=40,
data_brp=1,
data_tseg1=29,
data_tseg2=10,
data_sjw=10,
)
fd_timing_dict = dict(fd_timing)
assert fd_timing_dict["f_clock"] == fd_timing["f_clock"]
assert fd_timing_dict["nom_brp"] == fd_timing["nom_brp"]
assert fd_timing_dict["nom_tseg1"] == fd_timing["nom_tseg1"]
assert fd_timing_dict["nom_tseg2"] == fd_timing["nom_tseg2"]
assert fd_timing_dict["nom_sjw"] == fd_timing["nom_sjw"]
assert fd_timing_dict["data_brp"] == fd_timing["data_brp"]
assert fd_timing_dict["data_tseg1"] == fd_timing["data_tseg1"]
assert fd_timing_dict["data_tseg2"] == fd_timing["data_tseg2"]
assert fd_timing_dict["data_sjw"] == fd_timing["data_sjw"]
assert fd_timing == can.BitTimingFd(**fd_timing_dict)
def test_oscillator_tolerance():
timing = can.BitTiming(f_clock=16_000_000, brp=2, tseg1=10, tseg2=5, sjw=4)
osc_tol = timing.oscillator_tolerance(
node_loop_delay_ns=250,
bus_length_m=10.0,
)
assert osc_tol == pytest.approx(1.23, abs=1e-2)
fd_timing = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=5,
nom_tseg1=27,
nom_tseg2=4,
nom_sjw=4,
data_brp=5,
data_tseg1=6,
data_tseg2=1,
data_sjw=1,
)
osc_tol = fd_timing.oscillator_tolerance(
node_loop_delay_ns=250,
bus_length_m=10.0,
)
assert osc_tol == pytest.approx(0.48, abs=1e-2)
def test_recreate_with_f_clock():
timing_8mhz = can.BitTiming(f_clock=8_000_000, brp=1, tseg1=5, tseg2=2, sjw=1)
timing_16mhz = timing_8mhz.recreate_with_f_clock(f_clock=16_000_000)
assert timing_8mhz.bitrate == timing_16mhz.bitrate
assert timing_8mhz.sample_point == timing_16mhz.sample_point
assert (timing_8mhz.sjw / timing_8mhz.nbt) == pytest.approx(
timing_16mhz.sjw / timing_16mhz.nbt, abs=1e-3
)
assert timing_8mhz.nof_samples == timing_16mhz.nof_samples
timing_16mhz = can.BitTiming(
f_clock=16000000, brp=2, tseg1=12, tseg2=3, sjw=3, nof_samples=1
)
timing_8mhz = timing_16mhz.recreate_with_f_clock(f_clock=8_000_000)
assert timing_8mhz.bitrate == timing_16mhz.bitrate
assert timing_8mhz.sample_point == timing_16mhz.sample_point
assert (timing_8mhz.sjw / timing_8mhz.nbt) == pytest.approx(
timing_16mhz.sjw / timing_16mhz.nbt, abs=1e-2
)
assert timing_8mhz.nof_samples == timing_16mhz.nof_samples
fd_timing_80mhz = can.BitTimingFd(
f_clock=80_000_000,
nom_brp=5,
nom_tseg1=27,
nom_tseg2=4,
nom_sjw=4,
data_brp=5,
data_tseg1=6,
data_tseg2=1,
data_sjw=1,
)
fd_timing_60mhz = fd_timing_80mhz.recreate_with_f_clock(f_clock=60_000_000)
assert fd_timing_80mhz.nom_bitrate == fd_timing_60mhz.nom_bitrate
assert fd_timing_80mhz.nom_sample_point == pytest.approx(
fd_timing_60mhz.nom_sample_point, abs=1.0
)
assert (fd_timing_80mhz.nom_sjw / fd_timing_80mhz.nbt) == pytest.approx(
fd_timing_60mhz.nom_sjw / fd_timing_60mhz.nbt, abs=1e-2
)
assert fd_timing_80mhz.data_bitrate == fd_timing_60mhz.data_bitrate
assert fd_timing_80mhz.data_sample_point == pytest.approx(
fd_timing_60mhz.data_sample_point, abs=1.0
)
assert (fd_timing_80mhz.data_sjw / fd_timing_80mhz.dbt) == pytest.approx(
fd_timing_60mhz.data_sjw / fd_timing_60mhz.dbt, abs=1e-2
)