Hi Jason. I don't currently own that sensor, but in looking at the data sheet for the HC-SR04 sensor, it appears that it uses two digital pins for a trigger and echo. More than likely, the firmata would need to be updated slightly in order to achieve this. Jason may have a modified version as well. I'm going to go ahead an purchase one of the sensors and come up with a modified version for you. It may take a little while as I will be out of town next week, but I will post a version here when I can.
Thanks Andy.
Hi Andy, Did you manage to come up with a modified version of the firmata? having the same problem as Jason with the HC-SR04 sensor. Thanks in advance! Jeremy
Have you tried the arduino sketch that J Frolich came up with in this thread: http://www.grasshopper3d.com/forum/topics/using-ultrasonic-ping-sensor-with-firefly