Hacked $10 RC Car

erco

Senior Member
#1
Walmart sells this New Bright car for $10. Cut one trace on the PCB to disconnect radio, then tap into 4 H-bridge connections for forward, reverse, left & right. My latest 08M2 project for a series in SERVO magazine does a Figure 8 here.


And a quick PWM demo for motor speed control: https://www.youtube.com/watch?v=8NaTCHR8Apg
 
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erco

Senior Member
#3
Stationkeeping using a digital IR Obstacle/Proximity sensor.


Code:
do
b0=0 ' accumulator
for b1=1 to 50 ' loop 50 times
if pinc.3=1 then inc b0 ' increment b0 if sensor sees nothing
endif
next
if b0=0 then low 2: pulsout 1,4000'  100% triggered, reverse
elseif b0=50 then low 1:pulsout 2, 5000' 0% triggered, forward
endif
loop
 

jims

Senior Member
#8
Erco...I've never done a robot project and this intrigues me. I've done quite a bit of programming with using an IR "clicker" to control functions (pumps, heaters, lights, LED strips, etc) with various Picaxe chips. Do you think this "hacked Walmart car" would be a good project to get into the robotic world? Thank you, JimS
 

erco

Senior Member
#9
I think this is a good intro project. It's part 4 of a PICAXE Robotics series I wrote for SERVO magazine, it should be out ~ Nov 20 or so. My goal was to pick easy enough projects for beginners that are fun and achievable. This car project was simple but engaging. It ended up better than I hoped in terms of showing basic electronic hacking skills (disabling the car's radio control receiver, and tapping into the existing H-bridges) and programming a Picaxe 08M2. PWM (just one channel on the 08M2) is used on one H-bridge, and the IR proximity sensor can also receive commands from an IR remote control.

In Part 5 (~Dec 20) we will build a more traditional differentially steered robot, again using an 08M2. With a bit of luck, it may balance too, if the alkaline cells can keep up with the servo current demands.
 

erco

Senior Member
#11
Excellent. The sensor can be had on Ebay for under $2. It has four connector pins and a rectangular black IR receiver module, such as http://www.ebay.com/itm/For-Arduino...acle-Avoidance-Sensor-Smart-Car-/400786755690 Also shown in the video in post #6.

Edit: Fun facts about that "KeyesIR" obstacle/proximity sensor. The IR receiver module is an odd duck. It is the rare "continuous signal compatible" type (good), and its gain is fairly low (bad). There is an onboard 555 timer oscillator which sends out continuous unmodulated 38 kHz-ish IR pulses. Nearby objects reflect the outbound IR pulses back to trigger the active-low receiver, indicated by the 'Sled' SMT LED lighting up. The module has 4 pins: ground, +5V,OUT, and ENable. ENable lets you turn the 555's IR output on & off. Ignore the ENable pin, and leave the ENable jumper on. OUT is simply the output from the IR receiver module, so it can also receive standard IR remote codes (IRIN /SIRC protocol) when the 555's signals are not being reflected by any nearby objects.

Edit #2: I forgot that I made a video about this sensor last year: https://www.youtube.com/watch?v=M5iMpUZo9AA
 

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