Dual Optical Interrupt Timer: 25mm Gap
Dual Optical Reflection Timer: 25mm Gap
Optical Interrupt Timer: 75mm Gap
Time of Flight Sensor
Quadrature Rotation Encoder
Pressure Sensor: (0-1.45) PSI-gauge
Pressure Sensor: (0-25) PSI-gauge
Pressure Sensor: (0-7) PSI-differential
Pressure Sensor: (0-100) PSI-differential
Temperature Sensor: Ambient
Temperature Sensor: RTD
Temperature Sensor: Type-K Thermocouple
LED Strobe Light
Audio Signal Generator
Precision Audio Signal Generator
Audio Signal Sensor
Audio Signal Sensor: with DSP
12kHz Pulse Generator
12kHz Pulse Detector
Fiber Optic Link
Card Swipe Reader
Bar Code Reader
Laser Diode Driver
Hot Plate Controller
Mitutoyo Electronic Caliper Pickup
USB-HID Host Controller
USB Slave Controller
Real Time Calendar Clock
External LCD Display
Dual H-Bridge, Stepper Motor Drive
Light Duty DC Motor Drive
Medium Duty DC Motor Drive
Wall-Wart Power Supply
De-Walt Battery Power Supply
Solar Cell Power Supply
PDs, The Original Design Effort. When I first began this project, I settled on the USB 1.10 serial bus as the preferred communications link between the CB and the PDs . And my choice for an embedded controller was an 8-bit USB-enabled PIC processor. The photo below shows two examples of these older design efforts.
|Electronic Caliper Serial Port Adapter and Differential Pressure Sensor.|
The down side of this change was that I couldn't use any of the industry standard USB micro-controllers to design around. But the up side was that, by designing my own micro-controller in a FPGA, I was able to incorporate into hardware a lot of features that would have been impossible to implement using any industry standard USB micro-controller.
PDs, The Current Design Effort. Once the decision was made to abandon USB as my choice for the system's serial interface, the design of the PDs fell immediately into place. I had already done several USB Host controllers and USB-SIEs in Verilog, so having to forgo using an off-the-shelf USB part and create my own FPGA based micro-controller was an easy transition.
Working in Verilog allowed me to implement in hardware a serial bus with the exact features my system design needs. It also let me incorporate into a PD’s design, features I could never have had using a standard micro-controller chip. Here are just a few examples.
|CW from top: photo-gate timer,dual H-bridge motor driver, audio tone generator.|
The dual H-bridge motor controller PD can either micro-step drive one stepper motor or variable-speed drive two DC motors.
Since each PD can sync its own internal clock to the CB's to within a few micro-seconds, this allows not only the frequency of an audio tone generator PD to be controlled, but its phase as well. This opens up the possibility of using pairs of tone generators to do audio wave-interference experiments. One can also use a cluster of tone generators to create a steerable phased-array audio beam!
|12.5 kHz pulse transmitter for echo-location experiments. LED strobe light.|
The LED strobe light PD can be paired with an audio tone generator to do physics experiments involving driven mechanical systems. A tone generator PD can be used to drive a mechanical system, while a strobe light PD can be set to a frequency 1 to 2 Hertz off from the tone generator's. This allows students to see visually a system's response as the frequency of the tone generator is swept up/down.
|A USB adapter PD. This allows USB HID devices to be plugged into the WIDJETS CB|
A second advantage of such a PD is that memory sticks can be used for program transfer to/from a CB or to act as extra memory space for programs too large to fit in the CB's internal memory space.