Motor-Sensor Expansion Board
CX-MSEXP

The Handy Cricket Motor-Sensor Expansion Board adds two DC motor outputs (with power control) and four analog sensor inputs.

The DC motor outputs are named “c,” and “d,” and work just like the Cricket's built-in motor ports a and b. Commands on, off, thisway, thatway, rd, onfor, and setpower are used to operate the motors.

Power for the motor outputs is drawn from the Handy Cricket's 4xAA supply. PCB holes are provided for running an alternate motor power source into the Expansion Board.

The four sensor ports have the same pin-out as the two sensor ports built into the Cricket. The command “sens” reads the value of the sensor port. E.g., “sens 1” reports the value of sensor port 1. The sensor ports have 8-bit A/D converters; converted readings are in the range 0 to 255.

The sensor ports come with encoder software. Each of the four ports can provide raw counts and velocity readings when used with simple single encoders. The commands are “counts n” to report the number of counts on encoder n (n is a value from 1 to 4), “velo n” to report the velocity on that encoder (counts per 64 millisecond period), and “resetc n” to reset the counts reading to 0.

Sensors to be used as encoders must provide a signal that rises above 3.75v (a reading of 192 or higher) and falls below 1.25v (a reading of 63 or lower). When the encoder sensor value rises above 192, an encoder count is registered. When the sensor value falls below 63, another encoder count is registered. Each encoder input is sampled at a rate of 500 Hz.

When used pairwise, ports (1 and 2) and (3 and 4) provide two quadrature decoders. These accept signals from a pair of single encoders in the quadrature configuration (signals 90 degrees out of phase) to provide direction-sensitive counts information. The commands “quad12” and “quad34” report counts; “resetq12” and “resetq34” reset the counts to zero. Velocity information can be obtained with the single-encoder routines; e.g., “velo 1” or “velo 2” will report the velocity of quadrature encoder quad12.

Here is the Logo driver file for the Motor/Sensor Expansion Board.

Price: $29.00

Shipping weight: 0.20 lbs.