RoboSavvy Forum

a question to hivemind

2006-08-03T20:10:15+01:00

so where is the regulator located on the board anybody have a picture and a part number for the 3.3 volt replacement

thanks
rm

Statistics: Posted by Robotmania — Thu Aug 03, 2006 8:10 pm

a question to hivemind

2006-08-03T19:02:52+01:00

Simple, minimize size and complexity.
If you keep the PWM setting low it won't be collectively 300mA. A setting of 25 on all LED's would be approximately 10% or 30mA in average and still plenty bright on the LED's.

Statistics: Posted by Bullit — Thu Aug 03, 2006 7:02 pm

seems 2 B 2 much caution ...

2006-08-06T07:11:55+01:00

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Statistics: Posted by CaptKill4Fun — Thu Aug 03, 2006 6:43 pm

a question to hivemind

2006-08-03T18:14:32+01:00

Yes, the MR-C3024 can run at 3.3V. Subpilot, Hivemind and myself all run at 3.3V. To my knowledge none of us has had any problems related to that. All thats required is to replace the 5V regulator on the MR-C3024 with a 3.3V one. All the TTL signals change to 3.3V also. The rail voltage is what drives the servos. That's the same voltage that is coming from the batteries. The PWM lines are TTL. To use the MR-C3024's PWMs for LED's 3.3V modification is not required! We have made this change to support external devices that require 3.3V like 3.3V bluetooth modules and accelerometers.
Although the spec for the LED says the typical forward voltage for the blue LED is 4.6V, forward current starts much much lower. So at 3.3V don't expect 50mA of current through each blue LED. Notice the spec does not list a minimum forward voltage.
Whats important in this circuit is not to overdrive the MR-C3024's regulator (also don't overdrive the LED's - the resistors take care of this) The stock 5V regulator I think is 350mA. That has to supply the ATMega128, TTL signal to all servos, power for gyros, accelerometers, and LED's. So if you use the stock 5V regulator use the resistors for the LED's. If you use this mod be careful not to push the PWM's to the max setting. If you are running at 5V then at the the max PWM setting (using the prescribed resisitors and all 3 colors on) that would be a total of 300mA just to supply the LED's! Don't do that! 50mA is not enough to run the rest of the system.
I hope this clarifys a bit.
As usual proceed at your own risk. If you make mistakes you could damage your robot.

Statistics: Posted by Bullit — Thu Aug 03, 2006 6:14 pm

6V servos can run on 3.3V and still pickup a RoboNova-1?

2006-08-06T07:11:39+01:00

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Statistics: Posted by CaptKill4Fun — Thu Aug 03, 2006 5:21 pm

a question to hivemind

2006-08-03T20:29:03+01:00

well, as you can see in my video, they clearly do work properly, and if you are careful they will not damage the MR-C3024 (i once again take no responsibility if you do damage it though). I have my board running, as i said, at 3.3v, so for two leds that means they initialize earlier, and as for red, i just dont power the pwm port fully (not even close for all three) so i just find a balanced number to attain white. The plan at first would have been to use resisters for each LED, but they initialize early and work well, so why bother?

for example, i think to make my eyes a whitish color i would do this:
pwm 0,22 '==green
pwm 1,17 '==red
pwm 2,22 '==blue

And, ill even share my disco lights, i used it to test the LEDs.

'==written by Hivemind===========================================

DIM A AS BYTE '==green variable
DIM B AS BYTE '==red vairable
DIM C AS BYTE '==blue variable
DIM AUP AS BYTE '==A set up/down
DIM BUP AS BYTE '==B set up/down
DIM CUP AS BYTE '==C set up/down

disco_eyes:
IF AUP = 1 THEN A = A+1 '==if A set up then + 1==================
IF AUP = 0 THEN A = A-1 '==else A - 1============================
IF A < 1 THEN AUP = 1 '==check to remain inside of safe range==
IF A > 25 THEN AUP = 0 '========================================

IF BUP = 1 THEN B = B+3 '==if B set up then + 3==================
IF BUP = 0 THEN B = B-3 '==else B - 3============================
IF B < 3 THEN BUP = 1 '==check to remain inside of safe range==
IF B > 25 THEN BUP = 0 '========================================

IF CUP = 1 THEN C = C+2 '==if C set up then + 2==================
IF CUP = 0 THEN C = C-2 '==else C - 2============================
IF C < 2 THEN CUP = 1 '==check to remain inside of safe range==
IF C > 25 THEN CUP = 0 '========================================

PWM 0,A '==green
PWM 1,B '==red
PWM 2,C '==blue
GOTO disco_eyes
'================================================================

**Edited

Statistics: Posted by hivemind — Thu Aug 03, 2006 2:04 pm

425-1818-1-ND MultiColor LEDs in a HiTecRCD RoboNova-1

2006-08-06T07:11:16+01:00

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Statistics: Posted by CaptKill4Fun — Thu Aug 03, 2006 1:41 am

a question to hivemind

2006-08-02T16:22:49+01:00

You dont like the eyes do you? you are welcome to check out their ability to change colours here. The code simply adds a different number to each variable (1 per led).

As for the leds themself, i worked with bullit, he was the one who actually came up with it. We use (2) 425-1818-1-ND each color wired in parallel connected to one PWM each. From http://www.digikey.com.

We use them with no resistor with 3.3V regulator on MR-C3024. Although I would recommend using resistors as follows with the normal mr-c3024 5V regulator.

Wire each LED color in parallel, for red use a 27 ohm resistor 27EBK-ND, for green use a 6.2 ohm resistor 6.2EBK-ND, for blue use a 4.3 ohm resistor 4.3EBK-ND (all from http://www.digikey.com).

And of course i assume no responsibility if someone damages the controller or robot while trying to make this mod. but goodluck!

Statistics: Posted by hivemind — Wed Aug 02, 2006 4:22 pm

a question to hivemind

2006-08-01T23:45:00+01:00

What kind of led's do you have in your robot and where can i get them

thanks
rm

Statistics: Posted by Robotmania — Tue Aug 01, 2006 11:45 pm