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Topic: Looking for the cheapest USB-Serial (TTL) around (Read 3016 times) previous topic - next topic

Osgeld

the only realistic way I can see from what I have learned about this voodoo board to use this as a usb <> serial is to find the rx and tx pins leading from the usb device to the mcu, cut them and solder on new wires

voltage is easy enough the little voltage regulator has 5v in and ground on pairs of pins giving you a larger target

http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

TchnclFl

Well, believe it or not, I thought I'd give it a little shot.

I didn't cut up the board or anything, just removed all jumpers and the '430 from the board, then added one jumper between TX and RX for a feedback loop.  Using hyperterminal with default settings I get everything I send right back!  I'm getting ready to set up voltage dividers for Arduino TX :).  Anyone know if this chip is 5V tolerant?  That'd save some effort!

TchnclFl

Well, as of now, it doesn't look like communication is working through the Arduino...hard to tell though.

My computer seems to wait a random amount of time between when the code is compiled to when it starts uploading, so it's nearly impossible to time to reset push.  I tried tying the RST line from the launchpad to the Arduino's, but that didn't work.  I tried switching TX/RX (I never know how they're labeling it), but that didn't work either... *sigh*

Osgeld

#18
Aug 20, 2010, 03:12 pm Last Edit: Aug 20, 2010, 03:13 pm by Osgeld Reason: 1
interesting cause as stated before it didnt do jack for me in a loopback

wait, did you leave the MSP430 in its socket?
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

TchnclFl

Quote
wait, did you leave the MSP430 in its socket?


Nope, took it out.

Osgeld

#20
Aug 20, 2010, 08:38 pm Last Edit: Aug 20, 2010, 08:39 pm by Osgeld Reason: 1
weird, I tried it with no chip and all different ways you could jumper them and none would work

hyperterm, arduino serial monitor, putty, and linux console, never once saw an echo

(voodoo)

but before going down that path I did replace the temp monitor demo with a plain blink led program, wonder if that would have anything to do with it
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

TchnclFl

Well, the last thing I programmed was a modified version of shiftOut() that I made for the '430, but as the chip's not in I have no idea what that would do.  I checked, and the RST seems to be tied to ground even when it shouldn't be resetting...that troubles me.

westfw

The JTAG unit on the launchpad is going to manipulate RESET and TEST signals as per whatever the demands of the spy-bi-wire protocol used on the MSP430; I wouldn't expect it to do anything at all useful on any other cpu...

TchnclFl

Heh good point, I should have figured as much :P.

deSilva

Just an a-propos WRT the topic: Those $ 5.60 to 5.80 converters from ebay with cp2102 work fine! I have some for my breadboards.
But note that they have already a differentiating cap in the DTR line (which is consequently and correctly labeled RESET). The pulse generated will not go through the oversized 100nF cap of the Ardiuno boards. But that was no issue in my applications - on the contrary.

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