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Powering pixy through ICSP from Arduino on external power source is not working

Pixy Software
#1

Hello,

I am so happy with Pixy, it really brings new ‘perspective’ :slight_smile:

I tried the demo programs in PixyMon, all are running good, I can even control servos manually from PixyMon. Now I am trying to control it through an Arduino nano R3.

  1. Kindly I am having problem understading the following behavior, appreciate any ideas or advice.

When powering Pixy from Arduino (through I/O cable, on ICSP) such that the Arduino is using external battery (12v, 1300 mA) in Vin, then Pixy or Arduino will keep restarting (Pixy flashes red repeatedly aprox. each 1 sec) and Arduino reboots.

note thought, if I power it through Arduino USB instead, with same I/O cable, all will be good, Pixy starts, Aruino runs the demo program and I get Serial readings, but I can’t move the servos as expected since too much voltage drop through the Ribbon cable. So I switched to 3rd option, which is powering Arduino through Pixy using 10v into the power pins, This works too, but really not the best approach as I have to reduce the voltage 12v to 10v, waste energy into heat, where I need every bit of it for the mobile project I am building.

So question please, why do you think I am getting this looping restart behavior when I power Pixy through Arduino when on external source? I am not suspecting a power issue since the battery is fully charged and have 12v potential, also since no USB connection is involved, even the USB FT232 chip on Arduino is off and not using power.Also I tried powering the Arduino from pixy and it worked using the same connection, so I am not suspecting wiring issues…could it be a sofeware issue? thanks for any idea or suggestion.

Merci!
Fahed

#2

Hi Fahed,
Unfortunately powering through the ribbon cable can cause too much voltage drop when using the servos.

How are you powering your Arduino? Why don’t you reverse things-- have Pixy power the arduino instead of the other way around. So you have the battery plug into Pixy and power the Arduino through the ribbon cable.

thanks!

#3

Hi Rich, Thanks for your reply!

Actually I already tried Powering Arduino from Pixy and it works fine as mentioned earlier, but honestly I am not in favor of this approach given my project context. I am using a 12v battery, while pixy needs 10v. So I had to reduce the 12v to 10v using a series of diodes, then into Pixy power pins. Result is a loss of energy into heat in the diodes, which is a pitty and a bit of waste! someone might suggest to use lower voltage battery, but since I am also mounting the pixy on a robotic platform with 2 100:1 DC geared motors, I wanted higher voltage to get a bit higher speeds to move pixy around.

I really want to explore powering pixy through arduino, but I am lacking the understanding of the ribbon cable issue. is it due to the cable itself? or due to the electrical design of the pixy when powered through it?

I will try anyway some workarounds

1- powering pixy through arduino as usual, but instead of connecting the servos to pixy, I will connect them to arduino, and change the control in software.
2- Getting rid of the ribbon cable, and replacing it by low resistance jumper wires,and see the results
3- Getting rid of the ribbon and SPI and experiment with I2C

I will post back the results in case somebody finds them useful, and I will also be looking forward for any thorough explanation on the ribbon cable vs. servo issue. :slight_smile:

Thanks again
Fahed

#4

So you’re right about the wasted energy – but the Arduino (like Pixy) uses a linear regulator, which wastes energy too. So it shouldn’t make any difference from a wasted energy perspective…

#5

Yes I think I am going for a solution of pixy powers Arduino. I think the other way around is for applications not using the servos, but only targeting detection and reporting. Thanks for the help Rich!