potential duplicate digital input pin values reported

[soundanalogous]

This observation is based solely on looking over the code. There is a potential issue in that digital pin reporting is actually managed per 'port' in Firmware, but in firmata.js it's managed at the pin level. If we trace the code execution path, a potential issue emerges:

1. User calls digitalRead on pin D2. User also calls digitalRead on pin D3 and pin D4.
2. Each time digitalRead is called (3 times total in this example), reportDigitalPin is called.
3. In Firmata firmware (StandardFirmata), when the REPORT_DIGITAL message is received, the pin values for all pins in the corresponding digital 'port' are reported, regardless of the last value of any of those pins. This will happen 3 times for all of these pin since they are all on the same port.

One way to prevent this is to prevent reportDigitalPin in firmata.js from being enabled more than once for the same port.

[morganrallen]

I'm trying to track down a problem with digitalRead and I'm encountering behavior that looks similar to this. I'm calling digitalRead on pins 1-8 asynchronously like...

• pin = 1..8
  • set pinMode pin
  • setup digitalRead pin
    • (in callback)
    • reportDigitalPin(pin, 0)
  • externally trigger pin HIGH

There's a debug message inside the callback that starts reading out line...

pin 1 change: 0
.....

pin 1 change: 0
pin 2 change: 0

.....

pin 1 change: 0
pin 2 change: 0
pin 3 change: 0