Subject:
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Re: RCX Serial Hardware Hack
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Sat, 24 May 2008 19:13:49 GMT
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Viewed:
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23827 times
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In lugnet.robotics.rcx.legos, Bernhard Powolny wrote:
> http://www-date.uni-paderborn.de/pub/people/dasas/Beh03.pdf
I can't find it anymore neither.
> Then i have done as it is discriped in
> http://www.convict.lu/Jeunes/RCXCam/RCXCam_Journal.htm
> but i dont understand realy why we should do that?
>
> 1) To correctly use the H8 TX line with the CMUCam2 module, the driving RCX
> software MUST shut down the 38kHz carrier
>
> like :
>
> void infrared_off() {
> //! disable IR carrier frequency. // carrier_shutdown();
> //extern inline void carrier_shutdown(void)
> T1_CR =0;
> T1_CSR =0;
> }
The carrier should be quiet in any case, because it disturbs the TX signal.
> and
> 2)set the port6<7> pin LOW. Now the upper PNP transistor isn't conducting
> anymore.
>
> FOR WHAT reason...
We tried this,but it didn't work. Why, because the transistor will drain some
current, if the emitter has positive voltage and the base goes low. If the
carrier is off, and by accident you set long range, then you have the chance to
repeat what I did: kill a couple of infrared LEDs. Don't forget that they are
driven at high current, but under the condition of a 50% duty cycle that is
guaranteed by the carrier. If you shut down the timer, then the pin is high or
low - the timer stops and you don't know the actual port6<7> state -
If you have short range, the LEDs will rapidly heat also and only burn after a
while. So, if your IR-TX doesn't work anymore... check you LEDs.
> But how managed the people from to http://www.convict.lu/Jeunes/RCXCam/RCXCam_Journal.htm
> do it ????
With the CMUCam2 everything works fine, even at 19600 as I said.
> .
>
> more snap from the http://www.convict.lu/Jeunes/RCXCam/RCXCam_Journal.htm
> It is important to add a 100k pull-up resistor to the TX line !!! Otherwise the
> TX voltage will drop down to 0.45V it
Pulling up the TX line IS necessary-at least with the CMUCam2, because the RX of
this device is not pulled up.
No idea, why it should not work. We have run our the CMUCam2 for hours at many
occasions. We rebuilt the whole thing with another RCX, that we sent to Tufts
Univ. They successfully played with the stuff.
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Message has 2 Replies:
 | | Re: RCX Serial Hardware Hack
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| Dear Claude (...) A: Thank you for finding the PDF. (...) A: I will check ( measure the Voltage on the IF LEDS) should be approx. 9V betweem LED and Transistor if everything is off. (...) A: Now i had success . It works. (...) I have allready done (...) (16 years ago, 29-May-08, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | RCX Serial Hardware Hack
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| Hi As allready described in a other thread i have build a bluetoothconnection between pc and the RCX. There is one thing that the serial bluetooth is only available to tx/rx with a minimum from 4800 baud. At first i compiled brickos 0.9.0 with (...) (16 years ago, 20-May-08, to lugnet.robotics.rcx.legos)
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