Problems reading T/H/S Sensor

[stevendt]

Hi,

as some of you may have noticed, I'm trying to get some T/H/S working. I'm still struggling a little with the code, but I'm seeing some strange effects that some of you may be able to help with please . . . . .

I'm reading one T/H/S and one T/H sensor and get the following output from my program

[The temperature sensor output is as expected . . . . . ]
08/06/08 11:51:44 ROM 1020E189010800CD, Temp 31.75
08/06/08 11:51:45 ROM 1069298A010800BA, Temp 24.94

The T/H/S code is under test, so the messages below won't be too clear to others, but the output below is from the T/H/S followed by the T/H.
[This T/H/S is in the same case as the top temperature probe (stuck in the window at the moment) and the temperature value from the DS2348 agrees with the DS18S20. The humidity value is in good agreement with a "real" humidity sensor in the room (47%) and the voltages look reasonable. No idea what the Solar reading means but I can worry about that later.
Supply Voltage 3.29
Sensor Voltage 1.41
Temperature 31.31
Solar Rad 385
Humidity 43.89

The other humidty sensor currently reports :-
The temperature is close to the DS18S20 in the same case but the humidity voltage and calculated humidity are very odd (bad ?).
Supply Voltage 3.29
Sensor Voltage 10.23
Temperature 24.53
Humidity 100.00

The sensors are just connected to a DS90976U with nothing else on the network.

I've just tried reading the same sensors with the 1-wire viewer and get the same results.
Have just also tried the T/H sensor on its own in the 1-wire viewer and it displays the same values.

Any ideas folks ? At would appear that the T/H sensor is faulty - it's a brand new board received last week,

regards
Dave

 

[midon]

The other humidty sensor currently reports :-
The temperature is close to the DS18S20 in the same case but the humidity voltage and calculated humidity are very odd (bad ?).
Supply Voltage 3.29
Sensor Voltage 10.23
Temperature 24.53
Humidity 100.00

The sensors are just connected to a DS90976U with nothing else on the network.

The voltage reading on the DS2438 is what you would expect if the input to the VAD pin is shorted to ground. Check for that.

Mitch

 

[stevendt]

The other humidty sensor currently reports :-
The temperature is close to the DS18S20 in the same case but the humidity voltage and calculated humidity are very odd (bad ?).
Supply Voltage 3.29
Sensor Voltage 10.23
Temperature 24.53
Humidity 100.00

The sensors are just connected to a DS90976U with nothing else on the network.

The voltage reading on the DS2438 is what you would expect if the input to the VAD pin is shorted to ground. Check for that.

Mitch

 

[stevendt]

Hi Mitch,

thanks for the reply and the pointer to the problem. I'm a bit relucatant to poke around the surface mounted chips but the sensor is U/S as it is. Eric has agreed to repair/replace, so apart from the inconvenience of sending it back to the US (from the UK) I think that's what I'll do this week,

regards
Dave

The other humidty sensor currently reports :-
The temperature is close to the DS18S20 in the same case but the humidity voltage and calculated humidity are very odd (bad ?).
Supply Voltage 3.29
Sensor Voltage 10.23
Temperature 24.53
Humidity 100.00

The sensors are just connected to a DS90976U with nothing else on the network.

The voltage reading on the DS2438 is what you would expect if the input to the VAD pin is shorted to ground. Check for that.

Mitch