Subject:
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RCX Serial
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 27 Dec 1998 07:26:55 GMT
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Original-From:
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dave madden <dhm@paradigm.webvision./NoSpam/com>
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Viewed:
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1204 times
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I'm embarassed to post with such a trivial discovery, but in the hopes
of saving somebody a little time:
You can get the serial port to transmit under legOS by doing
*((char *)0xffd0) = 0x09; // TCR
*((char *)0xffd1) = 0x13; // TCSR
*((char *)0xffd8) = 0x30; // SMR
*((char *)0xffda) = 0x09; // SCR
*((char *)0xffd9) = 207; // BRR
and then:
if (*((char *)0xffdc) & 0x80) {
asm( "bclr #7, 0xDC:8" ); // SSR
*((char *)0xffdb) = 'X'; // TDR
}
Watch for 'X' on a serial port connected to the IR tower. The tower
shuts off after a second or two with no (transmit) activity, so be
sure to send characters occasionally to keep it turned on (the green
light indicates that the tower is receiving [and echoing] characters
on its serial cable, not that it has detected IR activity.)
The settings above turn off all Tx/Rx interrupts, so they're not
particularly useful except as proof-of-concept. Also, I'm not sure
whether you have to clear bit 7 of the SSR. Finally, I must be
missing something, because this doesn't work after a power-cycle with
legOS running -- the RCX ROM must be setting something serial-related
that gets cleared and not set up properly the next time.
BTW, my goal is to be able to speak serial to the RCX:
linux-box% minicom RCX
RCX Ready!
RCX> cat /dev/sensor1
77
^C
RCX> ls
prog1
RCX> ./prog1
Hello, world!
Sensor 1 value is 77
RCX>
So, in addition to serial drivers, I'll need devices, a filesystem, a
simple shell, and probably expansion memory...
regards,
d.
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