Let's Make Robots!

MY AGV development platform


I decided to do this as a blog as I plan for this to be a long term test platform as I mess around with different tech along the way.

OK I started by buying this RC truck chassis on eBay:

It uses a 7.2v NiMH battery and powers the motor using an ESC that delivers a few AMPs of 6v through a BEC to power a transceiver and the steering servo. Instead of a transceiver, I am hooking up an Arduino Fio and various components, housing them in a project box:

I said earlier that it uses an NiMH battery and you can see a LiPo here. that's because a smart charger and another NiMH battery are on their way and I am waiting to recharge the primary NiMH until I have the smart charger. On the right is a connector I made that can connect up to 3 servos or ESCs. It is connected to one ESC and one servo. Their data lines go to PWM pins on the Fio, the grounds are commoned (as are all grounds in all cases, so I will quit detailing that). The power line has voltage coming in because of the BEC on the ESC and it is 6v. It goes onto the the mini breadboard and is connected to VIN of the Fio. It also powers the "5v" power bus on the second breadboard by going through 2 diodes on the way there.

On the larger (but still fairly small) breadboard, I have a GPS powered at 5v and I run the Fio's 3.3v VCC to power a compass. I currently have a BluetoothMate that I plug into the FTDI on the Fio to receive some simple commands for RC operation so I can see that things work and it reports GPS locations. The compass is I2C and is currently not working. I need to swap it with an identical unit being used on another project to make sure it is good and then psych that out if so.

I have xBee modules that I will do some of my testing with, again wiring to FTDI on the Fio and I have some Nordic chips.  It's likely the breadboards will never go away on this unit.

Right now, it will move around as an RC vehicle. As soon as I get the compass working, I have code from another project I need to do some testing with which seeks a potentially changing GPS point (very similar to what Patrick did; in fact it would be even more similar had I found his before I started mine :) ).

Anyway this is my test ground vehicle. I will update as I try various things and hope to add a video as soon as it starts seeking...

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Stupid human! I read this page too fast:


There is a spot that says:


    http://arduino.cc/en/pub/skins/arduinoUno/img/bullet.gif);list-style-position:inside;color:#555555;font-family:Georgia, 'Times New Roman', Times, serif;font-size:14px;line-height:23px;margin:0px;">
  • I2C: 4 (SDA) and 5 (SCL). Support I2C (TWI) communication using the Wire library.

But before you jump to the conclusion that means the pins labeled 4 & 5, you have to read the text above it:

The Fio has 8 analog inputs, each of which provide 10 bits of resolution (i.e. 1024 different values). The analog inputs measure from ground to Vcc. Additionally, some pins have specialized functionality:

They are the only 2 pins on that page not referred to explicitly as labeled on the board.

Frustrating, but behind me. Hopefully I will test GPS seeking tonight!



That's a couple of Nordic modules (super low power 2.7G transceivers) I picked up on clearance at SFE. They are clearing then out  because they have an awful pin spacing, but the breakout boards (I have 3 on the way along with a 3rd module) are only about $1 each. I want to try these as an alternative for short range (at SFE, testing indicates I should get over 100m LOS) RC.  Bluetooth is unforgiving of temporary loss of signal and xBee (the 900 Pros I use) has an awesome range but sucks batteries.

My gender confused BlueTooth Mate module is also in the picture. I do that to testing modules that are FTDI pluggable - add a female header to go over FTDI pins and a male header for breadboarding. If you look close at the compass, you will see it has that also, but that is for a different reason. I expect it to be on a breadboard or in a socket, but then a 4 pin cable could be plugged in to extend I2C to another device.

The mailman just brought my new NiMH battery and smart charger, so I may get a video later, running down the new battery