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VLL ("visual light link") on a TI994a?


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#1 jrhodes OFFLINE  

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Posted Sun Jul 15, 2018 7:09 PM

It has been quite a while since i dug out my LEGO collection, but i remember that the Mindstorms MicroScout brick could be programed via "VLL" or Visual Light Link, which if i recall correctly, amounted to aiming a LED light at the bricks light sensor and pulsing a series of on/off flashes to store a "program" to turn X#-of-revolutions clockwise/counter clockwise in a mixed series which could be selected instead of the built in modes.

This program stays in the device until the battery dies, or is replaced with a new program.

I think the "next step up" so to speak, of mindstorms programmable brick, the Scout (Not MicroScout) could also use VLL, but i never owned one.

There is actually a program to write a custom program and transfer it to the brick from the Sony Pocketstation console's LED (which was used as a form of communication between another Pocketstation).

Given that the 32k sidecar already has a LED, do you think it would be possible to write a program to flash the 32k LED in the needed sequences to reprogram the LEGO brick when aimed at this LED?

m_scout.jpgtumblr_p4srexJBot1swiks1o1_1280.jpg



#2 TheBF OFFLINE  

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Posted Mon Jul 16, 2018 6:07 PM

It's just a bit on the CRU buss but...

 

I see the LED driver transistor on the board is connected to a multi-vibrator chip with a 1uf capacitor on it.

 

That will severely limit how fast it can flash.

 

Without modifying that capacitor I would guess no.

 

B


Edited by TheBF, Mon Jul 16, 2018 6:09 PM.


#3 TheBF OFFLINE  

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Posted Mon Jul 16, 2018 6:08 PM

That being said, if you have an RS232 board it is possible to make a led driver and connect it to a bit on the parallel port.

 

Just a thought.

 

B



#4 JB OFFLINE  

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Posted Mon Jul 16, 2018 8:23 PM

The RS232/PIO option is better, because you PROBABLY need an infrared light for data transfer rather than visible light.

I suppose if the new sidecar is using a red LED there's a chance of it getting through the IR window anyways, but I wouldn't place bets.

#5 Tursi ONLINE  

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Posted Mon Jul 16, 2018 8:44 PM

The 32k card isn't on a CRU bit, it's toggled when memory in the card's memory range is accessed. You'd have to stay out of 32k with your code to control the blinking, but it's feasible (I don't know to what rate.)

All the other card LEDs are (typically) on CRU bits, though, making them better candidates in terms of control. Rate, again, don't know. :)

#6 Vorticon OFFLINE  

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Posted Tue Jul 17, 2018 6:01 AM

Much easier to flash the RS232 card LED if you have it. You can do it straight from RXB without need for assembly.
First turn on the card with CALL IO(3,1,2432,1), then
CALL IO(3,1,2439,1) will turn the LED on, and CALL IO(3,1,2439,0) will turn it off. Interesting project and totally doable with RXB alone.

#7 TheBF OFFLINE  

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Posted Tue Jul 17, 2018 6:21 AM

The 32k card isn't on a CRU bit, it's toggled when memory in the card's memory range is accessed. You'd have to stay out of 32k with your code to control the blinking, but it's feasible (I don't know to what rate.)

All the other card LEDs are (typically) on CRU bits, though, making them better candidates in terms of control. Rate, again, don't know. :)

 

As yes. So it is.  Thanks!






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