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Author Topic: UART wiring and the $50 robot  (Read 1626 times)

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Offline LycusTopic starter

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UART wiring and the $50 robot
« on: August 11, 2008, 04:54:37 AM »
Just a quick question. I've just finished the UART tutorial for the $50 robot using a Pololu TTL to USB adapter with the CP2102 chip. I can communicate with the PC from the robot through Hyper Terminal just fine, but there is one little problem. Once I connect the TTL to USB adapter, the board lights up. That's without me even switching it on.

So do I actually need to connect the 5V bus and GND from the adapter to the board (on the sensor side, of course)?

And how can I start data logging when I turn the robot on, not as soon as I start Hyper Terminal?

Cheers

Lycus
There are 10 people in the world,
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Offline pomprocker

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Re: UART wiring and the $50 robot
« Reply #1 on: August 11, 2008, 10:00:59 AM »
The usb board gets its power from the usb cable.

you only need to hook up tx/rx/gnd to the board.


i learned this from having the same exact problem.  ;)
« Last Edit: August 11, 2008, 10:01:42 AM by pomprocker »

Offline Gertlex

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Re: UART wiring and the $50 robot
« Reply #2 on: August 11, 2008, 10:23:44 AM »
And how can I start data logging when I turn the robot on, not as soon as I start Hyper Terminal?

Start hyperterminal first?

If you're sending a bootloader to the same UART, though, just disconnect hyperterminal (there's an icon for that), then reconnect it when ready to turn on robot.
I

Offline LycusTopic starter

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Re: UART wiring and the $50 robot
« Reply #3 on: August 13, 2008, 02:38:03 AM »
Hi Guys,

Gertlex: Starting Hyper Terminal first doesn't work as I can only connect to the robot when the robot is turned on, and as soon as it starts the data logging begins, so by the time I hit connect the first section on the data has gone. But, I just had a thought. I'll just put a delay at the start of the code to give me time. Thanks for the help, and for giving me the impetus for the brainwave.

pomprocker: I tried hooking up Tx/Rx/Gnd, and even only Tx/Rx, but I still get the same problem, power is leaking onto the board somehow. Well, I'll do some measurements and see if I can find where the problem is. I assume that it has to do with the ATmega168, as that is where the Tx and Rx lines are plugging in to. ??? Strange.
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Offline Admin

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Re: UART wiring and the $50 robot
« Reply #4 on: August 23, 2008, 07:53:31 AM »
Found the problem? I'm with pomprocker on this one . . .

Offline sotu

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Re: UART wiring and the $50 robot
« Reply #5 on: August 23, 2008, 11:56:56 AM »
I also use pololu electronic parts in my robot.

I a servo controller, USB-to-serial adapter. And once i connect the USB-to-serial adapter to the computer's COM port by USB cable, a red LED starts glowing. So if i understood your first question right, you wonder if you can run your system without any batteries attached to your controller, this is wrong. All the controller (USB-to-serial dapter/TtL) does is to take some minimized required power, to indicate that it's actually plugged in.
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