Shared Projects by PeskyProducts

ST Microelectronic’s ultra-low-power real time clock coupled with Bosch’s BMP280 pressure and temperature sensor and ST’s M2402DFC 2Mbit 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 2 Mbits (256 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 Comchip low forward voltage Schottky 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 18 hours. Added ST Microelectronics' HTS221 16-bit, ultra-low-power relative humidity sensor. The board is now a tiny weather logging station: pressure, temperature, and humidity can be logged once per minute for 15 days!

Small breakout board for ST Microelectronics' high-G H3LIS331D accelerometer.

Bosch’s new BNO-055 9-axis motion sensor plus BMP280 pressure sensor. The BNO-055 has an embedded Cortex M0 ARM processor as well as accel/gyro and mag for a purely hardware absolute orientation solution. This is either a mini Teensy 3.1 shield or a conventional breakout board, choice is made via solder pads on back which bring 3V3 and GND out to edge pins. Sensor can be accessed either via I2C, UART, or HID-I2C on Windows 8 by changing solder pads PS0 and PS1 on back. Lastly, BNO-055 I2C address LSB can be changed via solder pad ADO so two can be on the same circuit, if desired.

Nordic Semiconductor’s low-power 2.4 GHz RF radio with pcb antenna and matching circuit per Nordic’s spec. Using much smaller XRCHA16MHz Murata crystal to reduce cost and board size. Adjusted antenna dimensions for better matching.

Appallingly small Teensy 3.x add-on board with 128 Mbytes of fast serial flash memory using an SPI communications interface. BGA-24 package Micron N25Q00AA flash chip with single chip select and all functional pins broken out. Board mounts onto the non-USB end of Teensy 3.x or Teensy-LC. Designed so it does not interfere with the I2C port on pins 16/17 of the Teensy 3.1.