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1  Using Arduino / Installation & Troubleshooting / Arduino Mega 2560 Tx LED stays lit following transmission on: May 25, 2011, 06:59:34 pm
The board appears to be working fine, except that the Tx indicator LED remains lit after any sort of transmission.

E.g. this scenario:
 1. plug Arduino into USB - the 'L' LED and Tx and Rx lights flash briefly (seems normal)
 2. after this, no LEDs are lit
 3. upload a sketch - all LEDs flash as expected while uploading...
 4. now the Tx LED remains lit indefinitely

Step 3 above can be anything that causes transmission - e.g. opening the port in Matlab to use the Arduino, and then closing it properly and deleting the serial object in Matlab, after which the Tx LED remains lit. Or using the serial monitor in the Arduino app.

Is this a problem? Does it mean it's constantly trying to transmit? It doesn't seem to be an issue with how I'm using the Arduino board (i.e. one can still open a connection to the board fine (e.g. in Matlab) while its in the Tx-lit state)

Any ideas? Cheers

2  Using Arduino / Programming Questions / General performance question on: May 18, 2011, 09:40:46 pm
I have a set up where Matlab reads data from an Arduino board (Mega 2560) constantly - coordinates of a joystick device.

As part of this I need to do some processing of the values that the Ardunio reads. I was wondering if for basic integer math operations, like division and multiplication, if it would always be faster for such processing to happen within Matlab, as opposed to within the Arduino sketch program?

I would intuitively think so given the massive differences in clock speeds between a modern PC and an Arduino board, but maybe not?
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