1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
import os
import sys
import periphery
from .test import ptest, pokay, passert, AssertRaises
if sys.version_info[0] == 3:
raw_input = input
i2c_devpath = None
def test_arguments():
ptest()
# Open with invalid type
with AssertRaises("open invalid type", TypeError):
periphery.I2C(123)
def test_open_close():
ptest()
# Open non-existent device
with AssertRaises("non-existent device", periphery.I2CError):
periphery.I2C("/foo/bar")
# Open legitimate device
i2c = periphery.I2C(i2c_devpath)
passert("fd >= 0", i2c.fd >= 0)
# Close I2C
i2c.close()
def test_loopback():
ptest()
# No general way to do a loopback test for I2C without a real component, skipping...
def test_interactive():
ptest()
# Open device 2
i2c = periphery.I2C(i2c_devpath)
print("")
print("Starting interactive test. Get out your logic analyzer, buddy!")
raw_input("Press enter to continue...")
# Check tostring
print("I2C description: {}".format(str(i2c)))
passert("interactive success", raw_input("I2C description looks ok? y/n ") == "y")
# There isn't much we can do without assuming a device on the other end,
# because I2C needs an acknowledgement bit on each transferred byte.
#
# But we can send a transaction and expect it to time out.
# S [ 0x7a W ] [0xaa] [0xbb] [0xcc] [0xdd] NA
messages = [periphery.I2C.Message([0xaa, 0xbb, 0xcc, 0xdd])]
raw_input("Press enter to start transfer...")
# Transfer to non-existent device
with AssertRaises("transfer to non-existent device", periphery.I2CError):
i2c.transfer(0x7a, messages)
i2c.close()
success = raw_input("I2C transfer occurred? y/n ")
passert("interactive success", success == "y")
if __name__ == "__main__":
if os.environ.get("CI") == "true":
test_arguments()
sys.exit(0)
if len(sys.argv) < 2:
print("Usage: python -m tests.test_i2c <i2c device>")
print("")
print("[1/4] Arguments test: No requirements.")
print("[2/4] Open/close test: I2C device should be real.")
print("[3/4] Loopback test: No test.")
print("[4/4] Interactive test: I2C bus should be observed with an oscilloscope or logic analyzer.")
print("")
print("Hint: for Raspberry Pi 3, enable I2C1 with:")
print(" $ echo \"dtparam=i2c_arm=on\" | sudo tee -a /boot/config.txt")
print(" $ sudo reboot")
print("Use pins I2C1 SDA (header pin 2) and I2C1 SCL (header pin 3),")
print("and run this test with:")
print(" python -m tests.test_i2c /dev/i2c-1")
print("")
sys.exit(1)
i2c_devpath = sys.argv[1]
test_arguments()
pokay("Arguments test passed.")
test_open_close()
pokay("Open/close test passed.")
test_loopback()
pokay("Loopback test passed.")
test_interactive()
pokay("Interactive test passed.")
pokay("All tests passed!")
|
