$12 Picaxe 20M2 Robot

erco

Senior Member
#1
I'm hacking Bangood's $12 D2-6 robot kit to make it Picaxe-controlled: https://www.banggood.com/D2-6-DIY-5...ing-Tracing-Obstacle-Avoidance-p-1108390.html

IMO the kit is a great value as-is, it has line-following, obstacle detection and Bluetooth/smartphone remote control. It works as advertised, comes with a 16-pin STC15W201S microprocessor. Surely reprogrammable by someone with more time than me. But I'm taking the direct path and swapping it out for a 20M2, which has a few extra pins to add a beeper and an IR sensor. The board has header pins which make it easy to access all the connections.

I've just started but I figured I'd mention it now since they are on sale for $11 for a few more days at IC Station. http://www.icstation.com/bluetooth-remote-control-smart-suite-tracking-kits-p-10171.html

Obviously there's some effort involved, but I think the end will justify the means. There are 3 SMT chips in the stock kit to solder, two 8-pin H-bridges and an LM339. Also an AA-sized 14500 Lithium-Ion battery is required. Obviously the whole 20M2 module must be fabricated.
 

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#6
Thanks erco, i would appreciate you uploading the full schematic.

Also i am curious about if the original stc15w201s is using some kind of PWM to control the speed of the 2 motors and what is the use of push button s2?
 

erco

Senior Member
#7
S2=mode switch, long press changes from default line-follow mode to obstacle avoid mode to Bluetooth remote control mode.

I think there is PWM, mainly observable in the Bluetooth remote steering mode when fine steering adjustments are visible. I'm not nuts about the 10 ohm resistors in series with the motor, they make movement sluggish. Will probably replace those with some dropping diodes. Not sure why they used those if PWM speed control was available.

BTW I added the schematic to post #5.
 
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erco

Senior Member
#9
I'll make the mod and test soon, but I need to video the stock robot first. I've been busy playing with the Bluetooth app.

Most any silicon rectifier diode should work, such as a 1N400x. Need two in parallel in opposite directions, head to toe.

Of course if PWM is effective then it might not need anything when Picaxe-controlled.
 

erco

Senior Member
#14
No, it was just freeformed. But if you're interested I'll work one up later. Buried right now in a paying robot job with 5x 20M2s. :)
 

erco

Senior Member
#16
That project is prototype for a client so I can't show very much. Three 20M2s manage a custom LED display w/sensors, one does motors, navigation, WiFi, BT, IR & sensors and one master controller.
 

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erco

Senior Member
#25
Didn't really make a schematic of my Picaxe board, just free formed it to plug into the headers on the D2-6 board, replacing the Chinese micro. Pinouts attached.

PinoutsB.png

D2-6b.jpg
 
#27
Hi,

Looks a very good value kit and a great idea to picaxe it.

Still, I am puzzled by the low supply voltage (3V). Is it powered by AA batteries? Motors should be rated for 1.5V-2V.
 
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