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Topic: Safe to jump output pins to serial pins? Or danger of damaging something? (Read 1 time) previous topic - next topic

Wout_fisheye

I've got a Tinkerkit (RIP) DMX master shield, which communicates with Arduino on pin 3 and 4. Can I safely jump these pins to pin 0 and 1 to use the hardware serial port? Or am I damaging pins in some way?

+ would I have to set pins 3 and 4 to INPUT?

Thanks,
Wout

DrAzzy

The pins must be inputs, if they're outputs, it could damage the chip. Connecting them with a resistor ( say 1k) instead of a jumper is safer.
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Wout_fisheye

Alright, and the serial port RX would still get triggered with the lower voltage due to the resistor?

Or is it in this case just limiting current?

DVDdoug

Quote
I've got a Tinkerkit (RIP) DMX master shield, which communicates with Arduino on pin 3 and 4. Can I safely jump these pins to pin 0 and 1 to use the hardware serial port?
Why?   What are yoiu trying to accomplish?   What's wrong with using pins 3&4 to communicate with the DMX, and leaving pins 1&2 to communicate with the computer/USB?

As a general rule, I wouldn't mess with pins 1&2...  I'd leave them for downloading, for the serial monitor, and otherwise communicating with the computer in the usual way.



DrAzzy

Alright, and the serial port RX would still get triggered with the lower voltage due to the resistor?

Or is it in this case just limiting current?
It's just to limit current, in case you screw up and set a port output. Ideally, you wouldn't connect 3 and 4.

But I just realized, a 1k resistor won't work, you need something smaller than 1k going to Rx on the arduino, since that's also connected to Tx on the usb-serial adapter through a 1k resistor (on the Uno). You could of course directly connect them if the shield was no longer connected to pins 3 and 4.

Ugh.

He probably wants them on hardware serial, due to the abundant limitations of software serial.
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pwillard

That's why people buy USB-TTL-Serial boards.  Pins 0 and 1 are "occupied" unless you remove the Arduino bootloader from the board.

DrAzzy

That's why people buy USB-TTL-Serial boards.  Pins 0 and 1 are "occupied" unless you remove the Arduino bootloader from the board.
The bootloader has nothing to do with the physical connections to the pins, the bootloader is software. You mean the USB-serial adapter, I think.
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Grumpy_Mike

The boot loader is the software that sets these pins to be inputs and outputs. If you remove that and program through the SPI then you can use those pins for what ever you want.

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