I've been using XBees directly connected to 1 sensor, sampling the sensor at regular intervals and sending it to a database. XBee has been working during 2 years without issues. I've used sleep modes to manage reads and save power as the project was solar powered.
Now I'm updating the sensor node with 3 resistive sensors: 1 for temperature and 2 for soil moisture.
I've a functional prototype that's working with an Arduino and using XBee just as a radio interface. To simplify things I want to use the sampling capabilities of the XBee and avoid the Arduino. Problem is that moisture sensors require an AC current to work fine, but manufacturer also provides a pseudo-AC method which is easy to implement in Arduino using two PWM outputs, idea is to power the sensor alternating voltage in both sides, using pulses of maximum 50 ms, so using two inputs to sample voltage is enough to finally calculate the value of interest.
Do you have any sample circuit that can manage sensors, based on XBee controller capabilities ? Is there any pin in XBee that can be used to wake up the sensors and measure the sensors in sync ?
Any idea ?