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ROB the Robot programming?
http://forums.nesdev.com/viewtopic.php?f=2&t=15769
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Author:  Pokun [ Mon Apr 10, 2017 2:59 pm ]
Post subject:  Re: ROB the Robot programming?

I guess so, but I'm wondering, it might be worth testing again before adding ROB to the wiki. UglyJoe seems to just have taken the commands from this Atari Age thread which has these 10. That thread also had some misconceptions I think.

In Block/Gyro there's a test mode that keeps making the screen blink green until you press SELECT. While this is going on ROB's LED will, if ROB is looking at the TV, blink somewhat slowly. This is for the user to adjust ROB's head until it's looking at the TV (LED starts blinking). But in our test program the TEST command will only make the LED light up, and there seems to be no way to turn it off (it might turn off automatically after a while, I don't remember). Therefore there might be another command that is used to turn the LED off or something. It's possible it's just sending the TEST command over and over though, but from my observations the TEST command is not a LED toggle.

I have a Famicom Robot but no CRT TV nearby at the moment, so I can unfortunately not do any tests.

Author:  lidnariq [ Mon Apr 10, 2017 3:06 pm ]
Post subject:  Re: ROB the Robot programming?

Do you have an LED? We can try tepples's suggestion pretty easily.

Author:  Pokun [ Mon Apr 10, 2017 11:48 pm ]
Post subject:  Re: ROB the Robot programming?

Yes I have some LEDs and other parts laying around. I could try it if someone told me what to do.

Author:  lidnariq [ Tue Apr 11, 2017 12:58 am ]
Post subject:  Re: ROB the Robot programming?

Well, as far as "super quick" options, I just tried plugging an "ultrabright" red LED into my NTSC NES deck video output, verified that I could see it flicker at 60Hz, and then verified that the Zapper could pick that up.

Should be an OK place to start. Might need a current amplifier to allow the NES to drive both a TV input and the LED at the same time.

Author:  Pokun [ Wed Apr 12, 2017 3:16 am ]
Post subject:  Re: ROB the Robot programming?

Current amplifier huh, I don't know electronics enough to know how to design a circuit for that.
I guess I could try working Robot Block's Direct mode in the blind for the sake of testing first though.

In what manner would the LED connect to the video output? I have some LEDs in various colors with built-in resistors designed for 5 V circuits. Could I just connect one of these directly to the RCA-plug's ground- and video-lines?

Author:  lidnariq [ Wed Apr 12, 2017 10:53 am ]
Post subject:  Re: ROB the Robot programming?

Yeah, I just connected VideoCenter --- |>| --- VideoShield and got something that worked.

That will probably only would work with "old" LEDs (red, orange, amber, yellow, yellow-green); "new" LEDs (rich green, cyan, blue, violet, purple, white) probably have too high of a required voltage.

I also tried VideoCenter --- |>| --- TV input center and separate Shield --- Shield and got something that ... technically worked but was very marginally visible. Just barely enough for me to see the output of tepples's Zapper test program.

The other final quick configuration you could try (which I've not tested) would be:
Code:
VideoCenter ---+--- TV input center
               |
               +-|>|-+
                     |
VideoShield ---------+--- TV input shield
but there's a chance that the TV's input impedence will be too small for the voltage to be high enough for any current to flow through the LED. This is the first one that even could drive both the LED and TV at the same time usefully, though.

The "current buffer" I was describing would be shaped like this:
Code:
VideoCenter ---+--- TV input center
               |
             ~10k
               |     c---|<|---Vext
               +--b|< npn
                     e
VideoShield ---------+--- TV input shield
Vext could be 3V from some batteries, 5V from somewhere inside the NES, or anything below your BJT's Vcemax

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