I was not the only one experiencing problems with owfs using the RS232 port
with a DS2480B chip not being detected.
I found that when performing a hardware power-on reset, communication starts
and the chip is found as expected
and the 1-wire bus shows up in localhost:3001.
Here is my start sequence:
- switching on the DS2480B
- connecting to the serial port over TCP: socat pty,link=/dev/mytty
tcp:192.168.1.41:10001
- starting owserver : owserver -p 4303 -d /dev/mytty
- starting owhttpd: owhttpd -p 3001 -s 4303
In the beginning that reset was not reproduceable ... I didn't wait long
enough when powering off (capacitors have to discharge)
I think this means that its a reset problem (at least its what I guessed
from beginning, therefore I tried poweron reset).
Concerning initial reset, the Maxim AN192 says
-set baud to 9600
-send break (2ms)
-delay 2ms
-flush
-write timing byte C1h
-delay 2ms
-flush
...etc
but also mentions:
The DS2480B is reset if it detects a space in the stop-bit position. The
easiest way to generate this is with
a serial break longer than a 9600 baud 8-bit word. If break is not available
on the host UART then
switching to a slower baud rate and sending a zero byte can simulate a
break. Switching to space parity or
changing to a 9-bit word length with a zero in the most significant bit can
also simulate a break.
which probably implies that this break is not easy to generate with certain
UART's.
Even though Paul Alfile told me that break and pause are sent by owfs, I
guess that break is not long enough or that certain UART's dont perform it
correctly, which could explain that some users have problems with owfs using
RS232 port and others not.
rgds
Beat
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