Shared Projects by dewhisna

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.

The ProMini PiDuino HAT Board for the Raspberry Pi 3 allows mounting of an Arduino ProMini to a Raspberry Pi as a HAT. Functionally, this board is similar to an Alamode board but without real-time clocks, GPS interfaces, and servo breakouts that aren’t needed for most projects and it’s designed to actually fit the Pi without having to insulate things to keep it from shorting out.

The primary use is to breakout connections for I2C, both 3.3V and 5V ready, and tie the ATmega328 of the ProMini to the Pi as a coprocessor for real-time I/O processing without needing a real-time kernel on the RPi.

The ProMini can interface either via asynchronous serial or as an I2C-slave. The ProMini reset can be driven via GPIO17, allowing full Arduino programming of the ProMini directly from the RPi Host.

Three RPi GPIO’s are also broken out to direct-connect ports for use with interfacing things like single-wire hygrometers. And all GPIOs from the RPi that are used for I/O by this board are ESD protected.

It has a standard Arduino Uno R3 shield connector footprint for add-on boards.

It also supports the ID EEPROM as per HAT spec, but will work on older 26-pin RPi platforms too, sans the ID EEPROM.

The ProMini board was chosen because it’s actually more price effective than manually mounting the equivalent circuitry directly to this board. It also uses the off-the-shelf quad bi-directional logic-level converter, designed to stack above the ESD protection diodes that are mounted to this board, allowing a multilayer part configuration while keeping all parts top-side.

Happy Pi Day!

This is a much improved LCD/SDCard/Keypad Interface board for the FlashForge Creator Pro 2016 (and similar) 3D Printers. It offers on-board voltage regulation, ESD Protection, proper voltage level translation, power supply decoupling, and most importantly a buffer for the MISO data line. The goal is to put an end to SDCard read problems.

The Bill-of-Materials, Schematic, and additional details are available on Thingiverse: https://www.thingiverse.com/thing:2007070.