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Problem with redirecting from serial device
- X-seq: zsh-users 17883
- From: Ian Petts <ipetts@xxxxxxxxx>
- To: zsh-users@xxxxxxx
- Subject: Problem with redirecting from serial device
- Date: Thu, 18 Jul 2013 15:59:32 +1000
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I have been playing around with weather station receiver software on the
Arduino. The Arduino outputs serial data over USB on device ttyACM0.
The incoming data is not timestamped, so I have a small awk script to add this
as the data is received:
dt = strftime("%Y-%m-%d %H:%M:%S", systime(), 0)
print dt " " $0
When I run the script with output going to the terminal, everything looks to
be working just fine:
ian@nibbler~% ./dt-add.awk < /dev/ttyACM0
2013-07-18 15:34:18 [OS V3 Sensor Capture/Decode]
2013-07-18 15:35:16 Wind Gust: 2.33 Wind Avg: 2.42 Dir: NW
2013-07-18 15:36:02 Temp: 17.11 Humidity: 61
2013-07-18 15:36:55 Temp: 17.01 Humidity: 61
As soon as I add a redirect or pipe to the above (to save the data to a file
or for further processing) no data appears:
ian@nibbler~% ./dt-add.awk < /dev/ttyACM0 > weather.out
# A few minutes later
ian@nibbler~% ls -lh weather.out
-rw-rw-r-- 1 ian ian 0 Jul 18 15:47 weather.out
I don't think it's a file buffering issue, I've left it go for several hours
with the same results. Even if I try 'more'ing the data I seem to get no
Dumping the raw data to a file seems to be fine.
< /dev/ttyACM0 > foo
works as expected.
Can anyone please explain where the issue is?
All computers run at the same speed...with the power off.
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