Arduino Uno + RasPi: Use serial to poll for commands every 10ms

Projects Interfacing w/ Software on the Computer
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My Arduino drives a little robot. The commands come via serial (USB) from as Raspberry Pi.

The Pi has a queue of commands (e.g. move 1cm forward) that it sends one by one to the Arduino. But since my Arduino logic has no means to store multiple commands I send a serial command from the Arduino to the Raspberry Pi every 10ms that polls for the next command. When a command is still being executed, the serial command is not issued. That way the Pi does not send commands when the Arduino is still chewing on a command.

This effectively means that the Arduino sends out a serial command (Serial.write("mor"):wink: 100 times a second when there is nothing to do.

Edit: I should add that the project requires that many small commands are sent. There will be hundreds of little commands that make up one continous motion. This is why I created such a short polling interval.

I am wondering: is sending such a constant stream of serial commands from the Arduino a bad thing? Does it consume a lot of energy? (Since I am creating a battery powered robot, this could be an issue.) Is there a more clever way to do this?

I appreciate your feedback.

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This effectively means that the Arduino sends out a serial command (Serial.write("mor"):wink: 100 times a second when there is nothing to do.

Why? You should send a request (for more) only when the last one has been executed. Then, you should wait for a new command before doing anything else.

Sending requests for more data using a timer is silly.

You don't see bank tellers calling the next customer that way, do you?

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If the data from the RPi is 64 bytes or less (so it will fit in the Serial input buffer) you can manage things like this

transfer the data from the input buffer to the working area
request new data
process the data in the working area
repeat.

That means the new data should have arrived in the background while your robot is moving and there is no appreciable delay waiting for it.

...R

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Thanks, PaulS, for your suggestions. I modified the code. Arduino only asks for new commands once now. The Pi, on the other hand, now has a way of storing this state ("Arduino is waiting for a new command"). This is important since there may not be a command when the Arduino asks for it but only at some point later in time.

Robin2, thanks. There is not a lot of delay right now. I might implement this solution in the future if I need it.