I have published accumulator monitor (called LiXXX watchdog) one year ago. This design uses buzzer to signalize low voltage cell(s) of three cells LiPol / LiIon / LiFePo battery.
Now it’s the time for more sophisticated entrance. One possibility is using of JETI DUPLEX 2.4GHz system. It allows to transmitt data back to transmitter (TX module) and display them with JETIBOX. The idea to use this feature for monitoring state of battery cells is then obvious.
JETI DUPLEX battery monitor
Although I haven’t got any RC car, my friend ask me for programming of RC car lighting system. I produced the code for the PIC16F819 microcontroller from Microchip. Finally, it can have 4 PPM channels as input (I used 3) and 12 outputs (5 of them are used) able to drive 25mA per one output (max. 200mA in total).
RC car lighting system
There are many systems transmitting on 2.4GHz available at the moment. Some of them are able to transfer more than 8 channels typical for standard PPM modulation systems. One of example is made by the czech company “JETI model” http://www.jetimodel.cz/index.php?page=products&old=0&category=4 . Their system is capable to transfer up to 16 channels. It is opportunity to control more devices than model itself … camera, autonomous navigation. The only task is to merge signal from two RC transmitters with the result usable as input to the transmitter module (PPM signal too).
I solved this task with two microcontroller PIC18F252, called “MASTER” and “SLAVE”.
RC merger
I have acquired the Graupner MC-22s RC radio since the end of the year 2007.
MC-22s Front View
Some years ago I took the decision to begin with RC models. Therefore there was a need to use computer based simulator for learning of control. And because I tried to have similar conditions as in the field, I wanted to use my RC transmitter at home too. One of the most famous free simulator was FMS and for this great software there was possibility to connect RC transmitter with computer with help of PIC from Microchip. But there was only PIC12C508 chip in the design and this type of chip was OTP version only (not nowadays, but in the past). So I modified code and used PIC12F629 / PIC12F675 instead of original one. I simplified scheme too, as You can see at the following picture:
