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Fix I2C init error on BeagleBone Black #22

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Merged
merged 4 commits into from
Nov 19, 2018
Merged

Fix I2C init error on BeagleBone Black #22

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3a1339c
Fix I2C init error on BeagleBone Black
pdp7 Oct 22, 2018
796e0a1
modify i2c init to fix issue on BeagleBone
pdp7 Oct 29, 2018
793537e
change the i2c init to just read 1 byte
pdp7 Oct 29, 2018
aea9d07
Attempt to write then fall back to read for i2c detect
pdp7 Nov 19, 2018
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14 changes: 12 additions & 2 deletions adafruit_bus_device/i2c_device.py
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Original file line number Diff line number Diff line change
Expand Up @@ -56,14 +56,24 @@ class I2CDevice:
with device:
device.write(bytes_read)
"""

def __init__(self, i2c, device_address):
# Verify that a device with that address exists.
"""
Try to read a byte from an address,
if you get an OSError it means the device is not there
"""
while not i2c.try_lock():
pass
try:
i2c.writeto(device_address, b'')
except OSError:
raise ValueError("No I2C device at address: %x" % device_address)
# some OS's dont like writing an empty bytesting...
# Retry by reading a byte
try:
result = bytearray(1)
i2c.readfrom_into(device_address, result)
except OSError:
raise ValueError("No I2C device at address: %x" % device_address)
finally:
i2c.unlock()

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