[Soekris] Problem reading the serial port

Soren Kristensen soren at soekris.com
Fri Nov 29 08:13:43 UTC 2002

Hi Pablo,

Pablo Berra wrote:
> Hi (sorry about my English),
> I want to implement a system using the DS1820 temperature sensors from
> Dallas Semiconductors. This chip use the 1-Wire interface connected at
> serial port (/dev/ttyS0).
> I am using the Net4521 with Linux (2.4.19) and digitemp (V 1.6 for passive
> adapter) for reading the temperature and it gave me the following error:
> digitemp -s/dev/ttyS0 -i
> Error initalizing OneWire device
> Error Searching for ROMs
> I turned off in initab and lilo config file the serial references... so the
> /dev/ttyS0 is completly free..
> also i tried to set the ConLock value (set conlock=disable) in the bios with
> error (dont know if this could help...)!!
> I try the same linux and digitemp version on another machine... and it works
> perfectly....
> Any clues?
> Thanks in advance.

The net45xx series manufactured until about 2 months ago had the RS232 
transceiver configured in a auto power saving mode where it turned 
itself off if there isn't any active inputs. That mean that devices 
powered from the serial port doesn't work.... Is that the case with your 
application ?

Older boards can be modified by cutting the thin trace from U5 (MAX3243) 
pin 23 to the capacitor next to it, and instead connecting pin 23 to pin 
22 with a solder bridge.

The updated boards are net4521 dated 020922, net4511 dated 020922 and 
net4501 dated 020910.



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