I've got this board from a local store. It's an L293D based dual DC motor driver. All the pins are labelled except the 5 on the bottom as shown in the picture below. Couldn't find any datasheet or manual for using this board.

enter image description here

I've connected the board's Vcc to Arduino's 5V and board's ground to Arduio's GND. Then put the IN1 to HIGH and IN2 to low, and got a voltage of 4.3 across the motor A's terminals.

Now what I want to do is use an external power source (11.1V battery) for the motor terminals, NOT the Arduino's 5V.

  • Are there any datasheet/manual for this board?
  • How do I use external power source with this board?
  • What are the pin-out/labels for those 5 pins annotated with a red box in the picture above?
  • $\begingroup$ Unless somebody visually recognizes the board, there is no chance of anyone finding any documentation without at least manufacturer information. $\endgroup$
    – 50k4
    Sep 3 '19 at 9:06
  • $\begingroup$ Also...you might want to try to measure continuity to see where those pins end up and identify them that way (or if their trace is visible try to follow that) $\endgroup$
    – 50k4
    Sep 3 '19 at 9:07
  • 1
    $\begingroup$ As discussed on Robotics Meta, identification questions are not considered off-topic. This is a practical, answerable question based on an actual problem that Raihanul is facing. We should also endeavour to be nice, especially to new members of our community. $\endgroup$
    – Mark Booth
    Sep 3 '19 at 13:30

A Google Image search on L293D board suggests that this is a widely available board manufactured by (or at least designed by) Deek-Robot.

The 5 pin connector mostly duplicates pins on the 6 pin green terminal block:

enter image description here

I suspect it is mostly useful for a quick motor connection when testing, whereas the green connector is used for a final motor connection.

Note that the Deek-Robot product page includes a link to the (very simple) circuit diagram and a link to the L293D datasheet.

Also, note that this chip can get very hot when pushed close to it's limits. 4 of the 16 pins are designed to be heat sinks to the ground plane, but it looks like this board doesn't have a very good thermal connection, so you may want to consider attaching a chip heatsink to the top side of the chip with thermal glue if it gets too hot. I've even known people to solder the heatsink to the chip via the heatsink pins as the plastic chip packaging is quite thermally insulating.


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