We took quite a break for the holidays – and other things distracting the team (like a certain member spending a lot of extra time at work). But, we are back to it now…
In our last post, we demonstrated how we could automate vehicular control by programmatically closing switches on the remote control using a simple IO board extending the GPIO interface of the RPi. Next, we want to give R2P2 “bat sight” by using an ultrasonic sensor.
The sensor we chose was the HC-SR04, which is a very inexpensive sensor that can be found on Amazon.com:
However, after reading about others’ experiences, we took heed that the RPi could not be counted on to produce accurate results operating the sensor, because the Linux OS could preemptively interfere with our attempts to measure pings and responses inside the required 60 ms sampling window. In order to eliminate this concern, we decided to trade in our piFace board for a Wyolum Alamode, which is essentially an Arduino (clone) that stacks onto the RPi GPIO interface:
While the piFace provided a circuit buffer between the GPIO and the sensors and controls, the AlaMode awards isolation via a wholly separate IO control interface that we will integrate with the RPi strictly via serial communications. Here you can see how things are “stacking up”:
Check back next time as we review the development of the Raspberry Pi <-> AlaMode (Arduino) integration! [R2P2]