E Shore Technologies - Online Robotic Center

Under this article, I am going to discuss on how to build the control system for a two wheels differential drive combat robot. The main parts that will be use in this project is 2 x HCMD3A, a SKPS and a SK40C.

SKPS is a adaptor/converter for PS2 controller (you can use wired or wireless PS2 controller) that help microcontroller to read the buttons and joystick from PS2 controller using only UART port. For this project, I will use wireless PS2 controller. (the PS2 controller looks fancy with the football player printed all over the controller, I simply get it from local gaming store).

SK40C is a starter kit for 40 pins PIC Microcontroller, featuring 2 input button, programming port, onboard 5V regulator and a LCD port ready for 2x16 LCD. I simply solder a female header to the LCD port, male header to the 2x16 LCD, and use 2 PCB stand to mount the LCD to the SK40C. You can also solder the 2x16 LCD directly to the SK40C. Its up to you. (click on the image below to view larger size of the image)

And for HCMD3A, it is a high current DC brush motor driver, that is suitable to drive high power 12V or 24C DC brush motor like Starter Motor (DC Starter Motor for Honda EX5).

Now, after you have all the components you can start to build the circuit board, using donut board. I use female header for the SKPS and SK40C, and IDC box header (10 way) for the HCMD3A. This give me flexibility in reuse all the parts in another project or replace any broken part. For the circuit connections and the schematics, I will discuss the detail under Part 2.

For the HCMD3A, since I will be using 2 units, I use PCB stands to “stack” them together. Make sure that the PCB stand is long around 3-4cm to give enough air ventilation space for HCMD3A (it get hot when running high current motor).

The power supply for both HCMD3A is 2 unit of Lithium Polymer battery 11.1V (2200mAh) in parallel (max voltage for Starter Motor is 12V, do not over voltage the motor) to produce enough current for the motor, the SKPS and SK40C will be using another battery as the power source. The battery I use is 2200mAh, 20C, which means it is able to supply constant 2.2 x 20 = 44A, and by paralleling two batteries, they are able to have total 88A constant output.

Since both HCMD3A is use for differential drive motor, it is advised to connect both power supply together to ensure both HCMD3A receive same voltage. You can use the extra pad at the HCMD3A to connect both power supply together (remember to follow the correct polarity).

Putting all parts together. The wireless PS2 Controller is the input of the system, the SKPS is the adaptor/converter between wireless PS2 Controller and PIC Microcontroller, SK40C as the main processing brain, 2 unit of HCMD3A as the motor driver, and the 2 unit starter motor as the output of the whole system.

Hardware List:

• 25A High Current Motor Driver 3A Series (HCMD3A) x2
• PS2 Controller Starter Kit (SKPS) x1
• Enhanced 40 Pins PIC Start-Up Kit (SK40C) x1
• Modified Starter Motor x2
• Wireless PS2 Controller x1
• 11.1V 2200mAH 30C LiPo Rechargeable Battery x2
• PVC Auto Cable(65/0.26) - 1 Meter x2                     
• 10 ways IDC cable – 20cm x2
• XT60 Connectors Male&Female (1 pair) x4
• 16X2 Characters LCD Module x1
• PIC16F877A Microcontroller x1
• Donut Board x1
• IDC Box Header x2

Part 1 Hardware
Part 2 Schematic
Part 3 Programming