LTH sensor. Can I detect a battery low condition?

XBee & XBee Gateway XBee - Zigbee
1

Hi all:

Question is so simple: Can I detect when a LTH sensor (battery operated) is going to a battery low condition?

I remember that it was possible but now I’m not able to find any related information, so I’m not sure if I dreamed it.

Thanks in advance.

2

Yes, setting DIO11 (or P3) to a digital input (value 3) allows you to monitor the ‘low-voltage’ alarm on the voltage regulator. This will return as the bit mased as 0x0800 in the normal IS data push used by the LTH when it wakes.

The LTH has a low-loss regulator (MIC 5239 last I looked) which tries to maintain 3.0 volt output to the device, and there is a digital signal when the regulator is about 5% too low (so 2.85v?)

If DIO11/P3 reads as 1/high, then the voltage is okay. if 0/low, then your batteries are ending their life.

In general, the low-power XBee (non-PRO, which normally ships with the LTH) can run at only 2.1 volts, so quite long after the low-battery signals. Most high-power (PRO) Xbee need 2.7 volts so ‘the end’ is much closer with them.

3

Thanks Lynnl, your help is, as usual, MUCH appreciated [:x]

4

Yes, setting DIO11 (or P3) to a digital input (value 3) allows you to monitor the ‘low-voltage’ alarm on the voltage regulator. This will return as the bit mased as 0x0800 in the normal IS data push used by the LTH when it wakes.

Please, Lynnl, can you confirm that DIO11/P3 is a mistake and you meant DIO11/ P1?

5

Oops, yes - I was reading an incorrect ‘code comment’ in some old code. It is P1.