Merlin & MerlinA

Merlin & MerlinA

Plug-in Boards for Parallax's QuickStart Board:

Merlin provides a dual motor controller (using TB6552)

MerlinA provides a 4-channel ADC (using MCP3204)

Top View Diagram:

Bottom View Diagram:

Merlin Basic and Full Kits Now Available!

Merlin is a plug-in board (or mezzanine) for the Parallax Quickstart board featuring the Propeller microcontroller.

Merlin features a dual-motor driver allowing you to power the wheels of a robot, like the Sparkfun Magician chassis.

The four servo headers also allow Merlin to be used with other robots, like the Parallax BoeBot (shown with full kit and also connected to the 4.3" touchscreen and breakout board):

Merlin comes as a Basic or Full kit:

Basic Kit: (click to enlarge)

$12.99 Introductory Offer with Free Shipping! (USPS First Class)

Includes Merlin circuit board plus two 3-pin female headers (for motor connection), four 3-pin male headers (for servos or sensors) and power jack (accepts 5 to 9 VDC input)

Full Kit:

$22.99 Introductory Offer with Free Shipping! (USPS First Class)

Includes the basic kit plus solderless breadboard, 4 plus 16 pin female headers (compatible with Propeller Platform), 8-pin female header, 8-pin dip socket, and an electrolytic capacitor.

To order, simply send an email to: ray@rayslogic.com with your request.

Assembly, Installation and Usage Notes:

When plugging Merlin into Quickstart, be sure that pins are lined up correctly. It is possible to be off one column either way (the long way). Also be careful that Merlin is facing the right way, it should not be the way that covers up Quickstart. Please look closely at this photo for the correct alignment (see how the edge of Merlin's 40-pin connector is right on top of a relatively large SMT capacitor):

Note that the white stenciled side of Merlin faces down. So, as you can see in the "Top View Diagram" at the top of this page, you want to solder the power jack, eeprom header, and servo headers to the non-stencil side (which is actually the bottom) of the Merlin board.

If you want to use servos, you will need to install the large capacitor, or the Propeller will likely reset when the servo moves a lot.

If you use Merlin to drive bigger motors than those of the "Magician" robot chassis and are using batteries only to power it, you may need to install a large capacitor (e.g., 500 uF) between VIN and Ground on Quickstart. These are pins 40 and 39. You can use the Quickstart's second 40-pin connector as a convenient place to install the capacitor.

If you also have USB power connected, you don't need the capacitor. This is because the USB power will keep power on the Propeller even if the battery power on the power jack is pulled down.

This requirement is due to the observed fact that two servo sized motors, when started, can pull down the battery voltage enough to make the Propeller reset.

A capacitor on Vdd is not as effective as one on Vin for this purpose. I think this is because once the Quickstart's 3.3 V regulator drops out, it takes time for it to come back and the Propeller can reset in this time.

If you are driving large motors from batteries only, it may be a good idea to provide a second power source for Vin or Vdd because there is probably some point where this capacitor alone won't be enough.

If this capacitor is needed but you don't want to solder anything onto your Quickstart, it is possible (although perhaps less attractive) to add this capacitor to Merlin between pin 40 and GND like this:

Schematics: