Project idea - need some input
CannibalRobotics
Posts: 535
So I'm thinking about an array of temperature sensors for my house. We just remodeled it and the nice efficient new HVAC system still has hot and cold spots. The contractor does not believe me so I want to collect some actual data. I'm planning on monitoring 6 rooms, the outdoor temp and humidity and solar intensity. This will be purely a data acquisition project as I have a PC dedicated to 'the house' for lighting and AV control. The central processor would just stream raw data to the PC via RS-232. Eventually this will morph into the input side of a more elaborate HVAC computer controlled system.
My plan:
Stamp BS2-SX for the controller.
for Temp, the Parallax 604-00002.
For Temp and Humidity, the 28018
And for solar intensity I'll read the current off of a cheese ball solar cell from a kit my son has long sense abandoned.
I want to keep the sensor board design as simple as possible. I'm thinking about running cat 5 to all of the temp sensors. It would carry power, clock and data to and from. I'd put each sensor on it's own board with an RJ-45 connector, maybe a voltage regulator a big electrolytic capacitor (35v/1000uF) to handle the transmit surge and the 0.1uF cap for noise recommended in the design spec. I'm thinking the longest run would be about 50'. The sensors will be permanently mounted on the ceiling of each room so I need to avoid batteries at each sensor. The sample rate is very slow (10 to 60 seconds) and I can poll each sensor individually.
What's the opinion of the brain trust here.
Do you think I should use line drivers or do you think that the stamp and sensor outputs will make the trip reliably.
Pending a good outcome I'm probably going to write another Nut's and Volts article about it.
Jim-
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Signature space for rent, only $1.
Send cash and signature to CannibalRobotics.
My plan:
Stamp BS2-SX for the controller.
for Temp, the Parallax 604-00002.
For Temp and Humidity, the 28018
And for solar intensity I'll read the current off of a cheese ball solar cell from a kit my son has long sense abandoned.
I want to keep the sensor board design as simple as possible. I'm thinking about running cat 5 to all of the temp sensors. It would carry power, clock and data to and from. I'd put each sensor on it's own board with an RJ-45 connector, maybe a voltage regulator a big electrolytic capacitor (35v/1000uF) to handle the transmit surge and the 0.1uF cap for noise recommended in the design spec. I'm thinking the longest run would be about 50'. The sensors will be permanently mounted on the ceiling of each room so I need to avoid batteries at each sensor. The sample rate is very slow (10 to 60 seconds) and I can poll each sensor individually.
What's the opinion of the brain trust here.
Do you think I should use line drivers or do you think that the stamp and sensor outputs will make the trip reliably.
Pending a good outcome I'm probably going to write another Nut's and Volts article about it.
Jim-
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Signature space for rent, only $1.
Send cash and signature to CannibalRobotics.
Comments
50 feet should be ok, you might need to lower your transmission speed to somewhere near 300 to 1200 baud, but it should be ok for that distance. If there is too much noise though, you might consider a differential drive or 4mA-20mA current loop configuration.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.