oh I see
so to read pin 2 I need to enable port 0
ahh, so I guess that was my misconception, I thought "port" was just another word for pin
So I doubt protocol docs or whatever will help me
Maybe you need to make that info a little more front and center? Even now knowing about ports, the only reference I can find to it is a comment in some code on the arduino site
sendDigitalPort(byte portNumber, int portData); //send an 8-bit port in a single digital message
And I have to store the old state to know what changed?
I don't see why that part is shifted to software, it would be way more efficient to do it in hardware surely?
session = new ArduinoSession(connection);
session.SetDigitalPinMode(2, PinMode.InputPullup);
session.SetDigitalReportMode(0, true);
session.DigitalStateReceived += Session_OnDigitalStateReceived;
...
private void Session_OnDigitalStateReceived(object sender, FirmataEventArgs<DigitalPortState> eventArgs)
{
var isSet = eventArgs.Value.IsSet(2);
Console.WriteLine($"Message is for port {eventArgs.Value.Port}. Pin2 value= {isSet}");
session.SetDigitalPin(10, isSet);
}
Do all the client libs work like this? You get zero delta information, just new state and you need to work out what changed yourself?
So I have a meg with like 56 digital pins, I would need to keep 7 blocks of 8 bit button states to know what changed?
Some firmata client libraries sort that out for you, it really depends on the particular library. The reason we use ports instead of individual pins is throughput. When updating on every iteration of the main loop, it's far more efficient to report 8 pins at a time rather than individually. However a buffering mechanism would solve the same issue, but it was not initially part of the architecture. It is something I'm considering however for Firmata v3.
you could send more efficiently - in the above use case you only need to send two values to tell me that pin 56 changed to 1
for a port you are sending 8
but I spose what, you must always send a byte or something?
still, by switching to PIN/STATE you lose 50% bandwidth at most, but you could gain a bunch of CPU cycles at the host
maxing out the CPU of the arduino is no big deal
firmata/protocol#68
A new feature would be added that enables reporting individual pins in addition to ports
A firmware implementation would use one method or the other
1 bit per pin
but in binary of course
so all I am saying is maybe allow a mode like 00110
but it can be sparse
ah I see, bits
duh
yeah I see, much bigger