Crazy - Mega 2650, can't upload sketch if connected to screw terminal board.

Development Tools IDE 1.x
1

Hope someone has some ideas of what's going one.
I have a 2650 plugged into a screw terminal board. Only connections on the screw terminal board are pins 0-39 are connected to the signal pin and GND of a MOSFET board. Not other connections.

This is so crazy. If the Mega is plugged into the screw terminal board the sketch with upload until it gets about 99% goes red displaying a timeout error.

BUT.... If I unplug the Mega from the screw terminal board the same sketch can be uploaded without error.

Same results on a different computer.

Any idea why a sketch can't be uploaded to a Mega if attached to a screw terminal board?

Makes no sense.

Thank you.

2

Pins 0 and 1 are used for uploading. Try it without anything connected to those pins. You have plenty other pins to use on the Mega.

3

Thanks - I will give it a try.

I did a bit more research and found others with the same issue. Posted a link to a reference page below.

Reference page Serial - Arduino Reference

Just so I understand.... Pins 0 and 1 are reserved for serial communications? Would that be for USB? As in the same pins as used for data in the USB port?

In the reference link posted above it says there are 3 additional serial ports.

The Arduino Mega has three additional serial ports: Serial1 on pins 19 (RX) and 18 (TX), Serial2 on pins 17 (RX) and 16 (TX), Serial3 on pins 15 (RX) and 14 (TX).

Do I need to worry about these pins as well?

4

Pins 0 and 1 are used for serial communication over the USB port. That means uploading to your board and also Serial.print(), Serial.read(), etc. You also have the option of using those pins for other purposes but you need to be aware that could interfere with their use for Serial communication. It's best to just leave those pins alone if possible.

Pins 14-19 on the Mega do have the capability of being used as additional hardware serial ports but they're not connected to the USB interface so you are free to use those pins as you like.

5

Got it, thanks.

Have another question. The Mega has a pull-up/down resisters built in and under software control. If I'm using the IRF520 MOS FET Driver Modules do I need a to use the software pull up or pull down resister? (And which one pull up or pull down.) + v to the signal pin fires the MOS FET.

I have 40 of the MOS FET modules connected. What's odd is one of the 40 modules indicator LED is in what appears to be a half state. The LED is slightly lit, but the MOS FET is in the "off" state. I'm wondering if the module is defective? Or if I need a pull down resistor.

Really appreciate the assistance.