Let's Make Robots!

powering a picaxe

Hello all LMR,

Calculon continues to work on his XMOS challenge, but has once again come across a snag.

The SNAG: He is trying to power his picaxe with a 5v out from a motor controller. It doesn't work.

The controller, a pololu Qik 2s12v10, is connected to a 12v. When measured with a multimeter, the motor controller shows 4.9 volts, 49 ma coming out to the picaxe. The breadboard indicator LED lights up. But the picaxe, she does nothing. When connected to 4 AAs, the voltage and current draw is the same. The only difference: with the 4 AAs, the picaxe works, but the LED is significantly dimmer, despite the similar current draw and voltage.

If both the controller and the 4 AAs are connected to the board, the picaxe works. For the life of him, Calculon does not understand the difference.

From the Qik user guide:

5V (out)
This line connects to the 5 V output of the qik’s voltage regulator and can be used to power additional electronics in
your system. It can safely supply up to 70 mA beyond what the board draws when VIN is 16 V. The closer the input
voltage is to 5 V, the more current the regulator can deliver without overheating.

Also, do not ask why a picaxe is important for the XMOS challenge. Calculon will not answer.

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Umm, some sort of noise on the line? Try some value of smoothing cap? I mean, it sounds as though it should be ok, what with the user guide quote 'n all.
Did calculon disablebod? Does THAT make a difference?

Most odd. have you verified that the serin pin is grounded correctly? Jocs recommendation is a good start and if your picaxe supports the mode,  you should try riks suggestion as well.

How fresh is the 12v bat that you are orginially hooking up to? Would it possibly have a low charge?

Is the axe standalone or is it connected to something that would draw power.

no noise on the line that Calculon is aware of.

serin pin is grounded correctly,

12v isn't fresh, but it has plenty of juice still (it can power the motors, plus my breadboard LED is hella bright)

the axe is connected to a keyboard and an LED. and works fine with 4 AA's

haven't got the disablebod, actually unaware of what that is. will research and report.

Calculon thanks you all.

on the disablebod

hrmm...try connecting a regular 5v reg if you have one to the 12v batt and connect that to the axe. See if it's powers up. Also do you just plug the power leads from the 4aa cells(this is 6v btw) or do you have a different breadboard that you move the picaxe to?

If this isn't a 08m/14m/20m, do you have the reset pin set up correctly?

I'm at a lost though atm as to what it could be....a wire diagram might work, but if you're going directly from the 5v to the power input leads, and doing the exact same thing with the 4 AA cells, I don't know....

Just another thought, try another ground point or use the ground direct from that battery.