Subject:
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Re: RCX sound circuit
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 27 Jun 2005 09:44:55 GMT
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Viewed:
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1129 times
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Hello Mark,
> Your circuit diagram checks out Philo, though a 47k resistor to ground should be
> added to the processor connection.
Quite possible as I obtained the schematics only with an ohmeter...
>
> I was wondering what the other NAND gate is used for. Input pin 1 traces to
> somewhere under the ROM. Input pins 2 and 13 and output pin 12 disappear
> elsewhere.
I spent some time again with my ohmeter, here is the schematics for this part:
http://www.brickshelf.com/gallery/Philo/RCX-comp/motor_cmd.gif
This is the motor driver control circuitry, data is latched when there is a
write to address x111 xxxx xxxx xxxx (binary). As I think H8 is used in mode 2,
A15 is always 1 for external access, so any write to fxxx should write to motor
driver latches. In the schematics, OUT_X_1 and OUT_X_2 are connected to Melexis
motor drivers in1 and in2.
> I suggest that a 3-input NAND gate was needed by the main computer circuit and
> that the speaker driver circuit just mopped up the spare gates.
Probably, yes ;o)
Philo
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Message has 1 Reply:
 | | Re: RCX sound circuit
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| Hi, I haven't really got the first clue what you are talking about here, but I would like to - any suggestions for reading up on this stuff? Thomas (...) (19 years ago, 27-Jun-05, to lugnet.robotics)
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Message is in Reply To:
| | Re: RCX sound circuit
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| (...) Your circuit diagram checks out Philo, though a 47k resistor to ground should be added to the processor connection. As soon as I get access to Visio again, I'll write it up and post it with a credit. I was wondering what the other NAND gate is (...) (19 years ago, 25-Jun-05, to lugnet.robotics)
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