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Unfortunately, multiplexing three-wire gas sensors like that is a bad idea: It will take quite a long time for a gas cell to recover and stabilize before producing meaningful readings. The gas se...
#2: Post edited
by
Olin Lathrop
·
2025-08-09T23:53:45Z (about 1 year ago)
- Unfortunately, multiplexing three-wire gas sensors like that is a bad idea:<ol>
- <li>It will take quite a long time for a gas cell to recover and stabilize before producing meaningful readings.
- <li>The gas sensors will be abused, with possibly degraded lifetimes. These things usually require two of the electrodes to be shorted when not in use, otherwise reactants can build up at one end, eventually rendering the sensor useless. Didn't you receive the sensors with something shorting two of the leads?
- </ol>
It looks like your gas sensor IC has standby capability in which it draws very little power. Note that during standby, the IC shorts the appropriate electrodes. There should be one dedicated sensor IC for each sensor, then you can multiplex the outputs of the sensor ICs.
- Unfortunately, multiplexing three-wire gas sensors like that is a bad idea:<ol>
- <li>It will take quite a long time for a gas cell to recover and stabilize before producing meaningful readings.
- <li>The gas sensors will be abused, with possibly degraded lifetimes. These things usually require two of the electrodes to be shorted when not in use, otherwise reactants can build up at one end, eventually rendering the sensor useless. Didn't you receive the sensors with something shorting two of the leads?
- </ol>
- It looks like your gas sensor IC has standby capability in which it draws very little power. Note that during standby, the IC shorts the appropriate electrodes. There should be one dedicated sensor IC for each sensor, then you can multiplex the outputs of the sensor ICs.
- <blockquote>We will poll the gas sensors at regular intervals of 15mts.In between if any gas sensor crosses the threshold it should wake up the TX and send data to RX.</blockquote>
- Your statements are inconsistent with each other. If you are going to poll the gas sensors every 15 "mts" (minutes?), then you can only discover the gas threshold got crossed at those times.
- It appears that your RF transceiver includes a programmable processor, although I only looked at the datasheet quickly. That processor needs to poll the sensors at least at the interval that is the maximum time that you need to know about high gas concentrations at. If all the gas levels are below the threshold, then it goes back to sleep. If either any thresholds are exceeded or a whole regular transmission interval has elapsed, then it sends all the gas levels over the RF link.
#1: Initial revision
by
Olin Lathrop
·
2025-08-09T13:14:17Z (about 1 year ago)
Unfortunately, multiplexing three-wire gas sensors like that is a bad idea:<ol> <li>It will take quite a long time for a gas cell to recover and stabilize before producing meaningful readings. <li>The gas sensors will be abused, with possibly degraded lifetimes. These things usually require two of the electrodes to be shorted when not in use, otherwise reactants can build up at one end, eventually rendering the sensor useless. Didn't you receive the sensors with something shorting two of the leads? </ol> It looks like your gas sensor IC has standby capability in which it draws very little power. Note that during standby, the IC shorts the appropriate electrodes. There should be one dedicated sensor IC for each sensor, then you can multiplex the outputs of the sensor ICs.