python hangs on serial write()

[aitorman]

Using the Pi Zero W, Jessie Lite and python3, whenever I try to write to /dev/ttyAMA0 python hangs indefinitely (longer than the set timeout). When I stop it with Ctrl-C this is the message I get:

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File "/usr/local/lib/python3.4/dist-packages/serial/serialposix.py", line 553, in write
    abort, ready, _ = select.select([self.pipe_abort_write_r], [self.fd], [], None)

This happens both in the python shell and when running it as a script, and I have disabled the serial console in raspi-config. This is the code I'm using, although I've tried many:

Code: Select all

import serial

port = serial.Serial("/dev/ttyAMA0", baudrate=115200, timeout=3.0)
port.write(b'A')

Could this be a hardware issue? The pi fell on the ground once when I took it out of the box, but I don't want to buy a new one before making sure it isn't a software issue.

[aitorman]

Using the Pi Zero W, Jessie Lite and python3, whenever I try to write to /dev/ttyAMA0 python hangs indefinitely (longer than the set timeout). When I stop it with Ctrl-C this is the message I get:

Code: Select all

File "/usr/local/lib/python3.4/dist-packages/serial/serialposix.py", line 553, in write
    abort, ready, _ = select.select([self.pipe_abort_write_r], [self.fd], [], None)

This happens both in the python shell and when running it as a script, and I have disabled the serial console in raspi-config. This is the code I'm using, although I've tried many:

Code: Select all

import serial

port = serial.Serial("/dev/ttyAMA0", baudrate=115200, timeout=3.0)
port.write(b'A')

Could this be a hardware issue? The pi fell on the ground once when I took it out of the box, but I don't want to buy a new one before making sure it isn't a software issue.

Add

Code: Select all

port.close()

Put this at bottom

That makes no difference, since the program hangs on the write() call before reaching the bottom.

[torus]

I have the same issue on a freshly installed Ubuntu 17.04 64-bit with Python 2.7. I run a Python script communicating with an Arduino Uno through a custom protocol running over serial communication, and my script freezes after few hundred of exchanges ...

The same script was working perfectly for days when it was running on Ubuntu 16.10 ...

[dgordon42]

Try changing all instances of "/dev/ttyAMA0" to "/dev/serial0" in your code.
That's 'serialZero', not 'serialOh'.

By default on a Pi Zero W, '/dev/ttyAMA0' is reserved by the system to talk to the Bluetooth Controller.
The 'serial0' alias is the new way to address the Serial Port, and should work on all Pi models running up to date Raspbian.

Hope this helps,
Dave.

[aitorman]

Try changing all instances of "/dev/ttyAMA0" to "/dev/serial0" in your code.
That's 'serialZero', not 'serialOh'.

By default on a Pi Zero W, '/dev/ttyAMA0' is reserved by the system to talk to the Bluetooth Controller.
The 'serial0' alias is the new way to address the Serial Port, and should work on all Pi models running up to date Raspbian.

Hope this helps,
Dave.

That worked perfectly, thanks

[chikiball]

Hi, I am still having this issue where the serial.write() hangs

I did:
- put enable_serial=1 in /boot/config.txt
- add serial.close() method at the end of the code
- change to /dev/serial0 or /dev/serial1 instead of /dev/tty0 or /dev/ttyAMA0

currently if i do ls -l /dev/serial* the result would be
/dev/serial0 -> ttyS0
/dev/serial1 -> ttyAMA0

any help would be appreciated

Thanks

[dgordon42]

Post the output from:

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grep -v -e ^$ -e ^# /boot/config.txt

and

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cat /boot/cmdline.txt

Hanging serial ports are sometimes caused by reading or writing to a port that's already in use.

Dave.

[kibria]

Try changing all instances of "/dev/ttyAMA0" to "/dev/serial0" in your code.
That's 'serialZero', not 'serialOh'.

By default on a Pi Zero W, '/dev/ttyAMA0' is reserved by the system to talk to the Bluetooth Controller.
The 'serial0' alias is the new way to address the Serial Port, and should work on all Pi models running up to date Raspbian.

Hope this helps,
Dave.

Thanks Mate.You saved my night

[EricSalemi]

The "timeout" option does not apply to write operations. You should use "write_timeout" option instead.

http://pyserial.readthedocs.io/en/lates ... l_api.html

[dsimonet]

Hi,
mine did the same thing until I changed in boot/config.txt

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enable_uart=0

to

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enable_uart=1

NB: On raspi zero W