Shared Projects by dewhisna

User-Interface HAT for the Raspberry Pi Zero. Note: Attaches to the BOTTOM of the Raspberry Pi Zero Board!

This HAT provides a debounced 6-button keypad interface and three I2C OLED connectors for mounting the little off-the-shelf 128x64 OLED displays readily available as either a single screen centered on the board, or two screens side-by-side.

It also has a connector for Serial I/O for debugging, plus a Real-Time Clock (RTC) module connector that works with the off-the-shelf DS3231 RTC modules.

Though I guess technically not a “HAT” since it doesn’t have the ID EEPROM. But it was eliminated because this board was designed to be used with another HAT board installed at the same time.

Dual CAN FD Interface HAT specifically designed for the Raspberry Pi Zero W. However, it can be used on any of the Raspberry Pi boards, even those with the smaller I/O header, as apart from the HAT EEPROM, only the first 26-pins are used. This version supports CAN FD (Flexible Data rate).

NOTE: This board mounts upside-down on top of the Raspberry Pi, with the NSD10-12S5 Isolated power supply module that goes on the bottom of this board on the outside of the stack. So pay attention to the orientation of the J1 connector connecting to the RPi.

Dual CAN Interface HAT specifically designed for the Raspberry Pi Zero W. However, it can be used on any of the Raspberry Pi boards, even those with the smaller I/O header, as apart from the HAT EEPROM, only the first 26-pins are used.

NOTE: This board mounts upside-down on top of the Raspberry Pi, with the NSD10-12S5 Isolated power supply module that goes on the bottom of this board on the outside of the stack. So pay attention to the orientation of the J1 connector connecting to the RPi.

The Optical Interrupter Shield V2 board, for ProMini PiDuino HAT, was designed to interface four off-the-shelf optical reflective sensors, such as my QRE1113 Sensor Board, used in raw-sensor mode, to a Raspberry Pi via an Arduino ProMini PiDuino HAT. This board expands on the V1 design with a better on-board debouncing circuit and four sensor inputs instead of only two. It also adds level-shifters to work with either 5V or 3.3V, as driven by the I/O Ref voltage pin.

ERRATA: To work better with the QRE1113 sensor, as this board was originally designed to do, change R3, R9, R15, and R21 from 10K to 47K. This change is necessary to boost the gain of the QRE1113 sensor by about five times, which is needed to get the sensor out of the linear region and into the switching region of operation. Without that change, the sensor will lack enough sensitivity to function adequately for use in the quadrature encoder application it was intended (and probably most any other application too).

PID Loop version of the AN3813K Brushless DC Motor Driver Arduino Shield for use with VCR Cylinder Motors. PID Loop Control done via on-board ATmega328 coprocessor. NOTE: This is a ATmega328PB. NOT a ATmega328P! The ‘B’ version micro is needed for the dual I2C interfaces as one is a master and one is a slave. The master communicates with the on-board DACs used to drive the AN3813K chip and the slave communicates with the main processor via the Arduino header pins.

See the AN3813K BLDC VCR Cylinder Motor Driver Arduino Shield V2 project for the PLL Version of this board. Both versions are viable solutions depending on preference of Analog PLL circuit or Digital PID via a microcontroller.

All smaller surface mount discrete parts are 1206 footprint except for the two 24pF capacitors for the crystal oscillator circuit for the micro (C307 and C308). Those two parts use 0805 footprints.

Note: Populate either C1-C3 with R1-R3 or populate C12-C14 without R1-R3. C1-C3 is a low-side filter and C12-C14 is a high-side filter. Only one set is needed. Preference is generally for C12-C14. In either case, those capacitors should be bipolar.

ERRATA: Atmel/Microchip recently decided to change the ATmega328PB (and its variants) to no longer support full-swing oscillator drive and therefore won’t drive the standard AT-cut crystal that this board was designed to use. In fact, I even discovered a bug in their die that if you use a crystal that almost starts but doesn’t quite, it can get into a mode where it switches back and forth between the internal oscillator and the external crystal and if you try to do flash reprogramming with it running in that mode, it will drive the charge pumps too long and fry the flash cells, destroying the chip. I accidentally fried one of my ATmega328PB chips this way.

Therefore, do NOT populate the Y301 crystal, the C307 or C308 capacitors, or the R312 resistor. And instead, set the low-fuse byte to 0xE2 to enable the internal 8 MHz RC oscillator at full speed. There is no good way, as it is currently designed, to attach a low-powered ceramic oscillator or even an external oscillator module to this board.

Perhaps a future version of this board will be spun to allow better oscillator options and higher speed operation. But, in all honesty, 8MHz is plenty fast, as the original design of this circuit, some eighteen years ago, was with a 68HC11 running at 4MHz, which since it was CISC instead of RISC, was less than an eighth of the speed of this ATmega328PB at 8MHz, and it was plenty fast.