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One Wire Assistance — Parallax Forums

One Wire Assistance

ArchiverArchiver Posts: 46,084
edited 2003-08-27 22:07 in General Discussion
I am trying to interface a BS2P to a Texas Weather Instruments Wind
Meter (no temperature) without success. I have downloaded the OW-
WEATHER.bsp written by Jon Williams, and Tim Bitson, but it does not
seem to work either. It returns 32F, 0MPH, and ERROR for temp, speed
and direction respectively. There are 2 possible causes for this as
far as I can tell, and any help isolating and fixing them would be
very helpfull.

The First, and Most Likely Cause: I made an ignorant wiring error...

The RJ11 coming from the stamp is wired as follows: With the female
end facing you, tab down, going left to right:

(5v) (Data Bus) (Gnd) (Gnd)

This is the wiring given by AAG for their weather station, and I am
assuming it is the same as the TWI I am using. I also have a 1k
pullup resistor on pin 15 of the stamp (the data bus). I have seen
many different recommendations for the Rpup, ranging from 5k to 1k or
less. I have tried a 1K, and a 4.7K (the most common 2
recomendations I have seen).


The 2nd Less Likely Cause: Software issue due to lack of
thermometer.

When I first tried the program it struck me as odd that it was
returning a value for the thermometer, despite the lack of the chip.
I thought this might be complicating things, so I went through the
program and had it skip the thermometer. The sensor is selected by
selecting a value for the variable sensor, 0 through 2 for Temp,
Speed, Direction respectively. I simply added an if statement, that
if sensor = 0, sensor = 1. This SHOULD have prevented the program
from going into any of the Temperature subroutines, and appears to
work. I still get 0mph and Error for direction.

I apologize for the very long question, but I was trying to be as
detailed as possible. This is my first experience with 1-wire chips,
so I apologize if anything about this question seems ignorant. I am
fairly familiar with the Stamps however, having used BS2's for about
2 years now. If anymore info would be helpfull just let me know, and
I will post what I can. Thanks in advance for any help.

C. Pond
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