Hi list,
Our project is developing an embedded system running Linux 2.6.35 on an i.MX53.
The system utilizes data from DS2505s through DS2482-800 bus master. We're
using owfs-2.8p15 and the initialization parameters are 'i2c=/dev/i2c-2:0 -m
mnt/1wire --allow_other'.
Physically disconnecting the DS2505 from the system requires 0.5-2 seconds.
OWFS has generally performed well with the application code reading uncached
data. However, system noise is causing bus search errors when the read Serial
Number (SN) on a bus doesn't match the first time read and stored SN, which
results in a logical disconnection of DS2505. The system noise doesn't seem to
corrupt the presence pulse due to its pulse width.
A suggested fix is to only do a bus presence check to maintain the DS2505 is
connected after the first read. If bus presence is not detected, then next
time bus presence and reading of SN to be implemented to restart the process.
Suggested fix is shown as a sequence below:
First time -> Read bus presence and 64-bit SN -> Result success -> Read memory
-> check integrity -> Result success
Second time -> Read bus presence -> Result success
| |
Nth time -> Read bus presence -> Result failure
N+1th time -> Read bus presence and 64-bit SN ... (Repeat as if it is first
time)
I'm requesting suggestions about the best way to implement the suggested fix.
Any pointers or suggestions on handling the noise problem would be greatly
appreciated.
Thanks,
Larry Howell
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