Info before ordering

Submitted by WarOfDevil on Sat, 01/30/2016 - 19:27

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Hi guys :) I'm planning to order a PicoBorg Reverse and one BattBorg for my project with my raspberry pi 2. I was reading the documentation of the two product but now i'm a bit confused regarding the connection between them. My project consist in rasperry pi 2 + piCamera and wifi usb stick to control a robot frame with 4 dc motor 6 V.

This is the robot platform that my father gifted for me: http://www.dfrobot.com/index.php?route=product/product&path=37_111&produ...

Connection for the motor it's clear for me, the 2 left motor connected in parallel on the M1 channel of PicoBorg Reverse and 2 right motor in parallel on M2 channel.

Regarding the power i'm confused. The battery pack (8xAA included in the kit of the BattBorg) it's connected only to the PicoBorg or BattBorg? How is divided the voltage? I mean 8 AA x1.2V= 9.6V so it means my motor will be powered with 9.6V and not 6V?

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piborg

Sun, 01/31/2016 - 13:33

In order to power both the motors and the Raspberry Pi the battery pack should be connected to both the BattBorg and the PicoBorg Reverse.

The easiest way to do this is to connect two wires into the BattBorg power terminals.
After that connect both these wires and the ones from the battery pack in parallel into the PicoBorg Reverse power terminals.

See the DiddyBorg assembly instructions from this step as a guide:
https://www.piborg.org/diddyborg/build#step36

This will allow PicoBorg Reverse to use the full 9.6V from the battery packs.
In order to use 6V you simply need to limit the maximum output level to:
6V ÷ 9.6V = 0.625 or 62.5 %

If you download the DiddyBorg example code you can see how we have limited the output to 6V.
You will want to change the "Power settings" section towards the top of the scripts so it is setup for a 9.6V supply instead of DiddyBorg's 12V:

# Power settings
voltageIn  = 9.6            # Total battery voltage to the PicoBorg Reverse
voltageOut = 6.0            # Maximum motor voltage

You should be able to use the DiddyBorg scripts to control your robot having made the power change above.
For them to work correctly the motors on the right side should be connected to M1.

WarOfDevil

Sun, 01/31/2016 - 17:10

Thank you for your answer, now everything it's clear :)
If i have understand the library PicoBorg use a PWM mode to power on the motor, the 62% value corrispond to my 100% if i want to use different speed for my motors.
I'm going to place my order :)

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