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 Robotics / 24131
24130  |  24132
Subject: 
Re: RCX sound circuit
Newsgroups: 
lugnet.robotics
Date: 
Mon, 27 Jun 2005 13:45:31 GMT
Viewed: 
877 times
  
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


In lugnet.robotics, Philippe Hurbain wrote:
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



Message is in Reply To:
  Re: RCX sound circuit
 
Hello Mark, (...) Quite possible as I obtained the schematics only with an ohmeter... (...) I spent some time again with my ohmeter, here is the schematics for this part: (URL) is the motor driver control circuitry, data is latched when there is a (...) (19 years ago, 27-Jun-05, to lugnet.robotics)

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