How to request a single pin status

Question

I have an xbee set up to remotely control an object outdoors. I have it connected to a battery and a solar panel. I want to monitor the charge of the battery and the simplest way I have come up with is to read the voltage of the battery.

I am using a voltage divider to reduce the voltage down to 0v - 3.3v from 0v to 20v. I plan on sending a command to turn pin 1 on to switch on a transistor which in turn will allow power to flow through the divider. I would then like to send a command to read the value of pin 3 which is hooked up to the divider. I will then turn pin 1 off.

I am doing this to save as much power as I can. I figure this is better then having the remote xbee use power to send multiple sensor packets when all I need is one at most in a day.

I cannot find a command to request single piece of sensor data.

Any ideas?

Thanks!

Comments

Sounds like you want a remote AT command but they vary by radio... what model are you using?

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Yeah I would have thought there would have been an AT command just to get the status of the pins rather than have to wait for the remote module to send out a packet on an interval. Plus on a large network that would get bulky having more than 10 modules constantly sending data.

I am using an "XBee 2mW PCB Antenna - Series 2 (ZigBee Mesh)" which I purchased from Spark Fun

I have been thinking about it and I might have a work around, but I have to test it to see if it will do what I want. But I consider it a hack.

I could set the module to only send pin data when one of them changes. First I would then turn pin 2 to monitor analog data. Then I turn pin 1 on to power the divider. Since the reading on pin 2 changed it should send me the pin data. Then after I get the pin data I set pin 2 to not monitor the data and turn pin 1 off.

I would also have to set the polling interval to 0, but that will be on setup.

So to prevent extra sensor data from being sent and to save battery power I would have to send 4 remote AT commands and the module would have to send back 4 remote at command responses and 1 sensor packet. Unless of course if I set my frame ID to 0. Then it should only send the one sensor packet. Which I guess is all I want to do is reduce the transmissions from the remote module. But I am a stickler and might want to make sure the divider is at least turned off so it's not dumping battery power. So that last packet I might have a frame ID for.

It should work but it seems overly complicated when there should be a simple AT command to say "Hey what are your current pin readings".

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OK that plan failed. The AT command "IC" which I thought would send me a packet when a pins value changes only does that for pins set for digital input not for analog which is what I need to use. The only way I can see how to do what I want would be to send the commands to set up the pins and then wait for an IO sample packet. Then I turn everything off and then clear out the rest of the extra IO packets that were sent.

That sucks. There should be a command to just get one set of IO sensor data.

Any suggestions?

Answer 1

The AT command "IS" should take 1 sensor sample. I would send the ATIS command using a 'remote AT command' API frame as you need to be in API mode to recieve a sample anyway.