Wifi Robot JBProjects. Wifi Robot August 2. Introduction Wifi Robot A remote control car that can be driven over the internet or with a laptop wirelessly from up to 5. It has a live feed network camera so that it can be driven without line of sight and a horn so that you can honk at people. A while ago I discovered the Linksys WRT5. GL router. Its very hacker friendly in that it runs Linux and some of the hardware has been reverse engineered. A bunch of alternative firmware versions have been written for this router. The version that this project uses is the customizable Linux firmware Open WRT. Along with great software for this router, a bunch of hardware hacks are possible. With a cheap, hackable, embedded Linux system at my disposal I knew I had to do something cool with it. So the Wifi Robot idea was born. In his last video YouTube user GusGorman402 showed us how to install OpenWRT and the RTLSDR drivers on a cheap used 20 router. The idea is that the router with. Aim DIY a wireless car based on Arduino. By controlling the car, we can see the other things in the remote location, or can monitor the security. Brush openWRT. Price level of software control. C with many builtin libraries integrated serial prepackaged development kit, little or no soldering involved. Openwrt Serial Port Programming In C' title='Openwrt Serial Port Programming In C' />The goal of this article is to give a high level overview of the project and provide some implementation details of the software and electronics. It is not meant to be a step by step how to guide, but there should be enough information for someone with motivation and some background knowledge in electronics and software to be able to make their own Wifi Robot. All of the source code is being released under the terms of the GNU GPL v. Hardware Car. Adding a network camera, router, heavier batteries, extra circuits, and a whole bunch of wires adds a lot of extra weight that the car wasnt designed for. Because of all of the additions, youll need to find a pretty large RC car. Thrift stores often sell RC vehicles without remotes for 3 5. I have bought a number of cars this way for taking apart. Vehicles in the 1 1. I bought this car for 5 at Value Village. I have taken apart about 2. RC cars. Nearly every single one of them used the Realtek RX2TX2 chips or a pin compatible alternative. The links are for their respective datasheets. What this means is that its really easy to interface to the cars existing electronics without having to put in a bunch of our own circuitry. Its possible to hook up a microcontroller directly to these pins Forward, Backward, Left, Right and directly control the car. Being able to leverage the cars original circuitry saves a lot of time and effort. Router. Ive modified my WRT5. GL to have 2 serial ports and a 1. GB SD Card acts like a 1. GB hard drive. The SD card is not used in this project, but one of the serial ports is. One is a console port, the other is TTS1 which we will be using. For this project Im using Open WRT White Russian v. There are more recent versions, but we dont need the latest and greatest software features for this project. Best Sprint Phone With Wifi. The software compilation guide details later uses this distribution, so that is why I chose it. Later in the article links and information are given that can help you wire up your serial ports and get them working. Microcontroller Selection. I evaluated three different microcontrollers for this project. Below is a summary of the evaluation. Arduino ATmega. 16. Freeduino Max. Serial. AVR Butterfly ATmega. C with many built in librariesintegrated serialpre packaged development kit, little or no soldering involvedeasier to program than the PIC Cintegrated seriallittle soldering involvedhard to program assemblyhave to wire up the circuit by handextra serial hardware required MAX2. Aextra programmer requiredpricebootloader error see belowintegrated peripherals cause weird output voltagesprice. I choose the PIC1. F6. 28. A for a few reasons I had a bunch of them around I have quite a bit of experience working with them I wanted a board with a small footprint, the PIC was the smallest footprint of all 3 options I wanted complete control over what the code was doing and this is very possible with assembly programming. The Arduino Freeduino Max. Serial is my second choice and I really liked how easy it was to get it up and running. The community support is great and its very easy to use. I originally used the AVR Butterfly development board. It was working fine until the batteries ran low one time. There is an error in the AVR butterfly bootloader detailed here that corrupts the code and doesnt let you reprogram it unless you load a new bootloader. To me, I just knew my car was working one day and not the next. It took quite a while to debug the problem and quite a bit of time to fix it so I scrapped that control system. I also found the output voltages to be unpredictable because the outputs are also driving the integrated peripherals like the LCD screen. Below I have included source code for the PIC and Arduino microcontroller platforms. Both have been tested so use whichever you feel most comfortable with. The Arduino Freeduino Max. Serial would be the most painless way to get running quickly. I bought this one. Steering Circuit. Im actually using two control boards in my car. The reason for this is that I blew the original drive transistors on the board that came with the car. Fortunately I was able to remove them and the RX2 chip which was also blown and salvage the steering circuit. Most of these toy RC cars have about 6 wires that go in to the steering motor assembly. This is because inside the assembly theres a metallic wiper that moves with the motor and the extra wires are used to relay which position the motor is in. Each different RC car will have a different setup for this wiper circuit, so its VERY useful to be able to use the one that came with the car. I blew the drive transistors because I was trying to drive the circuit at 1. V when the battery that drives the car would nominally be 9. V. The transistors are rated for 5. A, but evidentially I was driving them too hard and they failed in a spectacular plume of smoke. I took a board from another RC car and used its drive transistors. Im running this circuit at 1. V and it hasnt caused any problems. The transistors get quite hot though. Being able to use existing RC car circuits and not having to build your own H bridges saves a lot of time and money. Batteries. This project sucks some major battery power. I bought some high end RC car batteries for about 5. Bay. Theyre 3. 80. Ah and came with a 1. A smart charger. They can be found with this e. Bay search. Each battery takes about 1. Theyre 7. 2. V, however when theyre just charged theyre 8. V and when theyre dead no longer able to move the car they measure 7. V. I replaced all of the RC battery connectors with standard ATX power supply Molex connectors. This was so that I could connect them using cheap connectors I already had and so that it would be easy to make a splitter connector for doing power measurements. The batteries are wired in series for about 1. V when fully charged. Power Rails. 9. 2. V from 1. 2V 7. The 9. V rail was powered by putting 4 diodes in series with the 7. V rail. A diode takes 0. V to turn on. By putting 4 in series, we drop 2. V across them and now we have 9. V for the devices that need less than 1. V. After burning the first bunch of transistors I wanted to run the circuit at a lower voltage. The 7. 81. 2 regulator is only rated for 1. A but the motors would drain considerably more than that. Digikey sells a 7. A 1. 2V regulator for 1. I bought. I attached it to a heat sink because I thought that it may get pretty hot. After quite a bit of use, it doesnt even get warn, so the heat sink was not required. I didnt want to risk blowing the steering control circuit, so I put it on the rail closest to the original RC car battery voltage.