Shared Projects by PeskyProducts

ST Microelectronic’s ultra-low-power real time clock coupled with Measurement Specialties MS5637 pressure and temperature sensor and ST’s M24512DFM EEPROM in an appallingly small add-on board for Teensy 3.1. Power is supplied via digital write to general GPIO pins since the total power requirement never exceeds 2 mA. Communication is via I2C and there are 4K7 pullup resistors on board. The temperature sensor allows the Teensy 3.1 microcontroller to make periodic calibration updates to the RTC calibration register so the clock remains temperature compensated for maximum (~2 ppm or 1 minute a year) accuracy. The clock outputs the usual date, days, hours, minutes, etc. but also outputs tenths of seconds as well as hundredths of a second.The on-board EEPROM is useful for data logging and storing alarm patterns (music) for output to a small speaker. With 512 kbits (64 kBytes), lots of data can be logged and dozens of alarm sounds can be stored; one for every occasion! Added Taiyo Yuden PAS3225 2.6V 14 mF super capacitor and 1N4148 diode to provide power to the RTC time keeper even when disconnected from the microcontroller. The PAS3225 5 microAhour super cap can run the RTC (which needs ~330 nA at 2.6 V) for about 15 hours.

Breakout board with two independently addressable ST Microelectronics' 2 Mbit (256 kbyte) M24M02-DRC I2C EEPROMs designed to be mounted onto the Teensy 3.1 and use digitalWrite for power and ground due to the very low-power (< 2 mA per EEPROM) requirements. Can also be used as a traditional breakout board since VIN ranges from 1.8 to 5.5 V. Cutting one or both traces between the solder jumpers enables write protect mode allowing access to the data already written but disallowing further write operations. The write protect is reversible by simply soldering the junction again. Operating temperature range is -40 C to +85 C making this an ideal solution for portable/remote data logging when power and space are at a premium. EEPROM write operational for 4 million write cycles and data is retained for 200 years!

BMX-055 9-axis motion sensor plus MS5637 pressure sensor with the SENtral EM7180 sensor fusion hub with M24512DFM EEPROM to store the SENtral configuration file. SENtral takes 9-axis accel/gyro/mag from BMX-055 and performs hardware sensor fusion returning raw data, quaternions, linear acceleration, and heading, etc. First attempt at using wafer-level, chip-scale package (WL-CSP). Breakout board using the SENtral with jumpers to take power from edge pins for breadboard use or to mount directly on the Teensy 3.1 for comparison between open-source software sensor fusion and the hardware sensor fusion provided by the SENtral.

Wi2Wi W2SG0008i 1.575MHz GPS module add-on shield for Teensy 3.1. A mechanical switch toggles between UART and I2C output; 4K7 pullup resistors are on the SDA/SCL lines. Solder jumpers can be used to choose 4800 (default), 9600, and 38400 BAUD rates for NMEA protocol output to UART on Teensy Serial2, I2C supports both 100 kHz and 400 kHz rates. Solder jumpers can be used to take power and ground from the board edge transforming the shield into a conventional breakout board for breadboard use. The shield was designed for the 3V3 VIN of the Teensy but the LDK130 1.8V voltage regulator required by the GPS module can take up to 5.5V as input, making the shield in breakout-board mode ideal for any Arduino platform, even the Arduino UNO. The serial and I2C signals are logic level translated up to VIN on output from the board and down to the 1.8 V of the GPS module’s digital IO on input. There is a small SPDT button switch that sends the required ON/OFF signal to the GPS module. The passive chip antenna placement is less than perfect since it lacks a sufficiently ground-shielded feed line, which is not really wide enough to make the 50 Ohm needed. This is a compromise for the small size of the board, which allows the add-on function without overwhelming the Teensy form factor.

nRF24L01+ 2.4 GHz radio add-on board for Teensy 3.1 with smaller 16 MHz crystal and improved in-board antenna instead of low-range ceramic antenna