Our sensors are very sensitive to radio transmissions, so we need a way of gating them off during radio activity. Currently we use a uBlox Modem so we know when we are sending an AT command which will result in the radio being used. We need a way of achieving this using Notecard. I note that one of the card.attn options is to fire the Attn line when the radio connects. Please can you let me know if this is when the radio is active, or when the Notecard is connected in the general sense? If it is the latter, is there a way of signalling on one of the available pins only when the radio is transmitting?
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Hey @Mike,
We don’t provide a way to know when the Notecard’s modem is transmitting vs receiving, however there are both software and hardware ways of getting an approximation by knowing whether the modem is powered on or off.
- In software, the
card.statusrequest returns"cell": trueif the modem is powered on. - Although not documented this way, the
VACT_GPS_OUTpin has power only when the modem is powered. Note that on some SKUs this will be 3.3 and on some others it will be 3.8, so you should make sure your host is tolerant of that level.
TJ
TJ
Thanks. I can do both of these, but is the modem not powered when receiving? If both are brief, that would be OK though. If I stay with continuous connection does this mean the modem is always on? Maybe I would be better to structure the accesses and manually force the syncs. Does the Notecard do any housekeeping connections in the background?
One other thought I did have was to run the trace and look for the AT commands which caused transmissions, but this is not ideal on several grounds.
Any help you can give me would be appreciated. We can do some measurements using a spectrum analyser, but it is always difficult to reproduce all operating conditions.
Mike
Hey Mike,
is the modem not powered when receiving?
Yes, the modem is powered when sending and receiving.
If I stay with continuous connection does this mean the modem is always on?
Yes
Does the Notecard do any housekeeping connections in the background?
Yes, the Notecard does some housekeeping related to health and session. See System Notefiles - Blues Developers.
Maybe I would be better to structure the accesses and manually force the syncs.
If you want to go that route, you can toggle your hub.set request’s mode between "off" (disables syncs of all types) and "continuous". It’s an option, but it would definitely add some complexity to your firmware, so personally I’d only go down this route if you find the approaches above aren’t enough and you do truly need total control.
TJ
Hey @Mike,
Thanks for asking this question. We have a battery powered application, run the notecard in minimum mode, monitor hub.status to verify that the data has been transmitted, and then put the hardware to sleep until time for the next reading. I had noticed that hub.status says the data has synced, and we then put the hardware into sleep mode, but the green LED on the Notecard still shows activity for several minutes after our board goes to sleep. Our reading frequency is typically hourly.
In our case, if the cellular radio interfered with our sensors, on wakeup I could check card.status to make sure cellular was off before reading the sensors, then initiate the sync, which I believe turns on the notecard when in minimum mode. Doing it this way, I should be able to get my reading interval down to 5 minutes if needed.
@tjvantoll One question: In minimum mode, is there any way to turn off the cell power or do you just have to let the syncing process finish?
Don’t know if this helps you Mike, but I appreciated the question and insight I gained from TJ’s responses.
Karl
Hey Karl,
Sorry for the late reply here. Catching up after the holidays.
One question: In minimum mode, is there any way to turn off the cell power or do you just have to let the syncing process finish?
Even in minimum mode the Notecard must be allowed to finish up so all your state is saved and the system can clean up. When that’s done it drops back into a low-power idle.
TJ