herohans
Posts: 3
Joined: Sun Aug 02, 2015 3:10 am

Help with Magpi 51 robot coding

Thu Nov 24, 2016 2:06 pm

Hi All,

I'm trying to build the Magpi Issue 51 robot and I'm running into problems.

I followed the magazine instructions as best I could and hardware wise it looks to be okay. Powered by a 9V battery I get blinking activity lights on the zeroborg and the pi zero but the robot just sits there. Joystick doesn't seem to sync and I get a 'cannot access' the robots ip address on my phone's browser, no camera is installed yet.

I ran the zeroborg demo program and the wheels moved, so I'm wired correctly.

Do I have to edit/map zbJoystick.py with my joystick inputs?

What am I missing?

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mikronauts
Posts: 2705
Joined: Sat Jan 05, 2013 7:28 pm
Contact: Website

Re: Help with Magpi 51 robot coding

Thu Nov 24, 2016 4:19 pm

If you are trying to use one of the "normal" radio 9V batteries, there is your problem right there.

Those hold ~200mA @ 9V, so it will be drained in a second...
herohans wrote:Hi All,

I'm trying to build the Magpi Issue 51 robot and I'm running into problems.

I followed the magazine instructions as best I could and hardware wise it looks to be okay. Powered by a 9V battery I get blinking activity lights on the zeroborg and the pi zero but the robot just sits there. Joystick doesn't seem to sync and I get a 'cannot access' the robots ip address on my phone's browser, no camera is installed yet.

I ran the zeroborg demo program and the wheels moved, so I'm wired correctly.

Do I have to edit/map zbJoystick.py with my joystick inputs?

What am I missing?
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

herohans
Posts: 3
Joined: Sun Aug 02, 2015 3:10 am

Re: Help with Magpi 51 robot coding

Thu Nov 24, 2016 4:59 pm

I'm using a NiMH battery rated at 280 mAH capacity. Not quite as good as the ones with 300mAH capacity ones but the price was right.

My zeroborg is configured to run both it and the pi zero off the 9v. The magazine article only specified a single NiMH pp3 rechargeable battery.

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mikronauts
Posts: 2705
Joined: Sat Jan 05, 2013 7:28 pm
Contact: Website

Re: Help with Magpi 51 robot coding

Thu Nov 24, 2016 5:30 pm

280mAh @ 9V = 2.52WHr

Assume 85% efficiency if DC-DC converters are used, so 2.14WHr

assuming running robot takes only 700mA @ 5V on average(Pi Zero with WiFi, modest motor usage) 3.5WHr

You should have ~30min-~40min running time.

Since you are not getting that, I would look for the following possible problem areas, in order from likeliest to least likely:

- bad motor or short at output to motor (drains battery really fast)
- bad battery (it happens)
- bad wiring or battery holder (to battery)
- bad dc-dc converter (does not produce 5V properly for Pi)

I always build my robots with independent power supplies for the Pi's and the motor drivers, as the Pi's SD card is often corrupted on sudden power loss.
herohans wrote:I'm using a NiMH battery rated at 280 mAH capacity. Not quite as good as the ones with 300mAH capacity ones but the price was right.

My zeroborg is configured to run both it and the pi zero off the 9v. The magazine article only specified a single NiMH pp3 rechargeable battery.
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

herohans
Posts: 3
Joined: Sun Aug 02, 2015 3:10 am

Re: Help with Magpi 51 robot coding

Sun Nov 27, 2016 7:10 pm

I threw in a non-rechargeable, alkaline 9v in and the robot works! Or at least it did until my son spilled lime soda on the ps3 remote.

I think the web control code isn't fully booting because I don't have the camera installed. (I'm waiting on the rasp pi zero flex cable to arrive from china.)

Thanks for the help!

Hans

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