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Support Forum » Can i remove the programming header and still talk to the microcontroller

February 25, 2010
by sharadgupta7
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1) I was wondering if at the serial end of the usb-serial cable, i use 3 wires Tx, Recv and Gnd and directly plug them into my breadboard will it work

2) What is the use of the IC on the programming header ? Just curious to know.

3) Can i draw power from my USB port instead of using the 9V battery. I am told that USB works on 5V. If this works then i can possibly remove the voltage regulator also...

Please guide.

Thanks, Sharad

February 25, 2010
by pbfy0
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If there's an IC on the programming header,

1) no

2) it inverts the RS232 signal so the microcontroller can understand it

3) no

February 25, 2010
by sharadgupta7
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Thank you for your reply. The firswt two points are kind of clear to me but could you please elaborate more on the third question.

February 25, 2010
by mrobbins
(NerdKits Staff)

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Hi sharadgupta,

Our new USB to Serial cable allows for #3 (powering from USB port's +5V), but you have an older model with the separate inverter board, which doesn't allow you to grab USB power. You can certainly find your own way to tap into the USB power (for example, you could buy yourself an extra USB extension cord, cut it in half, and get the power wires). Alternatively, you can buy one of our new cables from our store, where the red wire supplies power from the USB bus, instead of requiring +5V from the other side like your version does. Hope that helps!

Mike

February 25, 2010
by sharadgupta7
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Thanks mike, this is what exactly i was thinking.. So with USB power, i can remove the voltage regulator and the resistor... Please confirm....

Thanks very much.

February 26, 2010
by hevans
(NerdKits Staff)

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Hi sharadgupta7,

You are correct. The NerdKit should be able to run just fine on USB NerdKit. However please be careful when using your computer to power anything you built. We start beginners off using 9V batteries for a reason. If you slip up and short something with a 9V, it probably can't source enough current to damage anything, and at worst you drained your $2 battery and burned a few $10 parts. The computer has the ability to source more current giving you the ability to really damage your parts as well as your computer. You should definitely try it, most of our prototyping boards here are running off USB power, but do be extra careful.

Humberto

February 26, 2010
by sharadgupta7
sharadgupta7's Avatar

Thanks very much Humberto for the explanation and forewarning...

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