Shared Projects by dewhisna

Simple 555 charge-pump circuit to create a negative tracking split supply voltage that mirrors the single supply input voltage.

It was an implementation of this design: http://www.syscompdesign.com/Negative-Tracking-Power-Supply_b_89.html for testing.

NOTE: This circuit isn’t stable and will generally go up-in-smoke. I advise forgetting this one and use the LM2662 based circuit instead, which works well.

DO NOT BUILD

NOTE: This board has been replaced with the new Version 2 board.

AN3813K Brushless DC Motor Driver Arduino Shield for use with VCR Cylinder Motors with precision speed control with feedback.

Specifically designed to be used with the Arduino ProMini PiDuino HAT and the STM32F746G Discovery Board, but can also be used on any Arduino Uno R3 compatible target. Supports both 5V and 3.3V logic with on-board level-shifters.

ERRATA: The footprint for the main AN3813K IC is wrong. The chip is an 18-Pin Shrunk DIP 0.550", 0.070" pitch (13.97mm, 0.1778mm pitch) (SDIP018-P-0550) and this board has the 18-Pin Wide DIP 0.600", 0.100" pitch (15.24mm, 2.54mm pitch). An adapter for the footprint exists, but this board has been replaced with the new Version 2 board that is correct.

DRV10975 Brushless DC (BLDC) Driver Interface Board

The Modulated Reflectivity Sensor Driver Board, a.k.a. the Arduino OptoInterrupter PLL Shield for the ProMini PiDuino HAT, was designed to interface two off-the-shelf optical reflective sensors to the Raspberry Pi via an Arduino ProMini PiDuino HAT.

Unlike the OptoInterrupterShield for ProMini PiDuino HAT, this version uses a Phase Locked Loop (PLL) circuit to modulate the reflectivity sensor to prevent false triggering of the sensor from ambient light.

The optical reflective sensors are used to detect the presence of an object by reflecting an infrared LED back to a phototransistor. The Arduino ProMini on the PiDuino HAT will allow “real-time” sensor timing with an accuracy of +/- 4uSec, using a standard 16MHz ProMini board.

Since the ProMini PiDuino HAT, which this board was designed for, uses standard Arduino Uno footprints, this board can also be used on other Arduino compatible boards. It does, however, require an Arduino board that has 5V compatible I/O pins, as this board is designed to run at 5V.

ERRATA: For proper operation, replace both C2 and C7 with a 0-Ohm Resistor/Jumper (i.e. DC coupling the input instead of AC coupling it). And replace both R1 and R13 with a 0.01uF capacitor.

For a much better frequency adjust range for most sensors, change resistors R7 and R19 from 33K to 47K and install a 180K resistor for both R8 and R20 (both currently labeled “N/A”). This change gives a VCO center-frequency of 14.215 kHz and a usable operating range of 8.79kHz - 20.65kHz, though fold-over on the ends will take it down to about 5.5kHz and up to around 33kHz. The original circuit had a 16.375kHz center-frequency and a range of 4.75kHz to 55.5kHz. But most sensors prefer 10kHz-12kHz and seldom function well above 25kHz.

The non-inverted PC2 output and/or the inverted ~PC2 output are the preferred output selections. PCP and ~PCP selections work, but need more signal post-processing.

For sensor input, use non-inverted PC2 Output for an Active Low output and inverted ~PC2 for an Active High output.

For push-button operation (either on-board push-buttons or an external push-button connected across “K” and “C” terminals), there are two options:

1) Without the sensor connected: add a 0.1uF cap across the “K” and “C” terminals (i.e. across the push-button). With this configuration, the non-inverted PC2 output will be Active Low and the inverted ~PC2 output will be Active High.

2) With the sensor still connected: Force the sensor into reflection, by placing a reflective target in front of it. No additional 0.1uF capacitor is needed in this configuration. But, the non-inverted PC2 output will be Active High and the inverted ~PC2 output will be Active Low, the opposite of the other configurations.

Note: All surface mount discrete components are 1206 footprint.

The Optical Interrupter Protoshield board the for ProMini PiDuino HAT was designed to interface two off-the-shelf optical reflective sensors to the RPi via an Arduino ProMini.

The optical reflective sensors are used to detect the presence of an object by reflecting an infrared LED back to a phototransistor. The Arduino ProMini on the PiDuino HAT will allow “real-time” sensor timing with an accuracy of +/- 4uSec, using a standard 16MHz ProMini board.

Since the interface circuit required for the Optic Interrupter is small relative to the board size needed to fit the standard Arduino Uno pinout, this board was designed as a complete prototyping shield. The two test switches for testing the interrupter inputs have been left floating with breakout pads so they can be tied to any circuit. A reset button and user defined LED have been added in addition to a power LED and D13 LED.

Since the ProMini PiDuino HAT uses standard Arduino Uno footprints, this board can also serve as a prototyping shield for other Arduino boards and/or is interchangeable with either platform.

The V+ bus is tied to the IOREF voltage, allowing operation at either 3.3v or 5v and there’s extra connection pads for all Arduino I/O pins.