Two Years of VEX

Mike MartinKing HS, Riverside, CA

February 22, 2013

Purpose

• To share two years of ideas and findings with POE, CIM, and GTT teachers.

• To stimulate questions and discussion about VEX in the classroom.

Battery Storage and Charging

The New Test Bed

The VEX Gear Box

The VEX Gear Box

The VEX Gear Box

Other Gear Boxes

Attaching LEDs to a VEX Structure

Attaching LEDs to a VEX Structure

Inventor Parts

Using FischerTech Parts with VEX

Cortex Capabilities

• The Cortex is extremely versatile. Any sensor that falls within specifications can be connected.

• Analog characteristics: – 3 dB bandwidth of 16 kHz. – Analog input range: 0.0 v to 5.0 v. – Tolerant of -0.5v to +5.5v. – Only configurable as analog inputs.

• Digital characteristics: – 3 dB bandwidth of 150 kHz. – Needs 0.0 to 0.6 volts for a low and 2.5 to 5.0 volts for a high. – Tolerant of -0.5v to +5.5v. – Can drive a 1 mA load to 1.6v or lower for a low and 1.4 volts or higher for a high.

Basic Analog Sensors

• Connect basic analog sensors to the Signal and +5V lines on the Cortex

• Configure them as a light sensor or potentiometer in ROBOTC

Basic Analog Sensors• The Potentiometer, Light

Sensor, and Line Follower sensor types all perform simple A-to-D conversions on sensors, so any of them can be used with simple 3rd party analog sensors

• Any sensors you configure will appear in the Sensor debug window, and can be accessed using the SensorValue[] command

Basic Analog Sensors• The Touch and Digital In

are basic sensor types and can be used with the basic digital sensors

• Any sensors you configure will appear in the Sensor debug window, and can be accessed using the SensorValue[] command

• If wired incorrectly, the sensor may have inverted logic values (pressed = 0)

Basic Digital Sensors

• Connect basic digital sensors to the Signal, +5V, and ground lines on the Cortex

• Configure them as a touch sensor or digital input in ROBOTC

Basic Digital Sensors

• Connect basic digital sensors to the Signal, +5V, and ground lines on the Cortex

• Configure them as a touch sensor or digital input in ROBOTC

Red - +5VGroundSignal

Advanced Sensors

• Advanced sensors (ultrasonic, gyroscopes, ect) require that you perform calculations on the raw sensor data to get useful information (centimeters, degrees-per-second, ect)

• These calculations are often referred to as “Sensor Drivers”

• Value-returning functions can be very useful in these instances

Other Findings and Ideas• Don’t do POE Activities 3.1.1 through 3.1.6 (or the CIM

equivalent)– Too much Copy and Paste– Doesn’t give programming practice– Activities written for older version of RobotC

• Instead, give the students ‘scenarios’ that they can use as programming practice– Prepare your own– Use the one I developed (on flash drive or email me with a

request)• There is a document on the flash drive which details

the EXACT order to set up a Cortex to communicate with a computer.

Questions?