Martin’s DIY Internet connected smart humidifier project:
The project uses a DHT22 temperature sensor mounted to the side of the enclosure for better ventilation and reliable reading:
I threw in a ultra-cheap I2C OLED status display to get a visual reading. Milling the box so that the OLED shows was pretty nasty, hated it. I cut a piece of paper and placed it on top of the cover, below the transparent lid to cover up for the lousy milling job
The humidistat switches on and off the humidifier as needed, the humidifier itself is plugged in to a plug in the relay. The auto detects when water is out and stops, so I didn’t have to care about that.
Internet connected smart humidifier - [Link]
by Francesco Truzzi :
Some time ago I came across a new chip from TI, the HDC1000. It’s a temperature and humidity sensor with I2C interface and requires little to no additional components. It comes in an 8BGA package: we can all agree it’s pretty small.
Some of the peculiar characteristics of this chip are that it has a DRDYn pin which goes low any time there is a new reading from the chip (so you can precisely time your requests) and that the sensor is located on the bottom of the IC, so that it’s not exposed to dust and other agents that may false the readings. Also, it has an integrated heater that can remove humidity from the sensor.
So I developed a very small breakout board for this chip as well as an Arduino library (yay, my first one! raspberryPi and nodemcu might come next).
HDC1000 temperature and humidity sensor breakout, with Arduino library! - [Link]
If you’ve read my last post you’re already familiar with my Inductance Meter project: http://soldernerd.com/2015/01/14/stand-alone-inductance-meter/. At that time the hardware was ready but there was no software yet. That’s been corrected, the inductance meter is now fully functional.
From a high-level point of view the new software is very similar to the Arduino sketch I wrote for the Inductance Meter Shield (http://soldernerd.com/2014/12/14/arduino-based-inductance-meter/). If you look a bit closer, you’ll notice some differences for several reasons:
This project uses an entirely different microcontroller: A PIC 16F1932 instead of the Atmel Atmega328
This code is written in C (for the MikroC for PIC compiler by Mikroelektronika), not Arduino-style C++
The display I’m using here comes with a I2C interface rather than the familiar Hitachi interface
Stand-alone Inductance Meter - [Link]
The PCA8565 plays a very important role in the real time systems like digital clock, attendance system and tariff switching. In applications where timestamp is needed, PCA8565 real time clock is a good option. It provides the following benefits: low power consumption, allows the main system for time-critical tasks, and more accurate than other methods.
The PCA8565 is a CMOS real time clock and calendar optimized for low power consumption. A programmable clock output, interrupt output and voltage-low detector are also provided. All address and data are transferred serially via a two-line bidirectional I2C-bus with a maximum bus speed of 400kbps. The built-in word address register is incremented automatically after each written or read data byte. It provides a year, month, day, weekday, hours, minutes and seconds based on a 32.768kHz quartz crystal. It features alarm and timer functions, low current, and extended operating temperature range of -40 degrees Celsius to +125 degrees Celsius. It further contains an 8-bit year register that can hold values from 00 to 99 in BCD format, which also compensates for leap years, thus leap year is automatically corrected.
From the application circuit, the PCA8565 can be used to perform standard RTC functions, such as tracking the actual time and date, or acting as a reference timer. To support power management, the PCA8565 can be used to wake the microcontroller from hibernation mode. In systems that use a PLL, it can serve as a system reference clock for the PLL input. The PCA8565 can also be used as a watchdog timer, or as an activation timer to start measurements or initiate other functions.
PCA8565 Application Circuit - [Link]
by Pieter @ piconomic.co.za:
If you can beg, steal or borrow an Atmel ISP programmer, then you can use the Arduino environment to develop on the Atmel AVR Atmega328P Scorpion Board. An Arduino on Scorpion Board guide, Optiboot bootloader and example sketches have been added.
If you own an Arduino Uno board, you can now try out the Piconomic FW Library risk free without abandoning the creature comforts of the Arduino environment. You can use the existing Optiboot bootloader to upload code. I have added a getting started guide for the Arduino Uno. There are examples, including a CLI (Command Line Interpreter) Application that creates a “Linux Shell”-like environment running on the Arduino Uno so that you can experiment with GPIO, ADC, I2C and SPI using only Terminal software (for example Tera Term)… it is really cool!
Piconomic FW Library 0.4.2 released - [Link]
Teensy-LC (Low Cost) is a powerful 32 bit microcontroller board, with a rich set of hardware peripherals, at a very affordable price!
Teensy-LC delivers an impressive collection of capabilities to make modern electronic projects simpler. It features an ARM Cortex-M0+ processor at 48 MHz, 62K Flash, 8K RAM, 12 bit analog input & output, hardware Serial, SPI & I2C, USB, and a total of 27 I/O pins. See the technical specifications and pinouts below for details.
Teensy-LC maintains the same form-factor as Teensy 3.1, with most pins offering similar peripheral features.
Teensy LC – Coming March 2015 - [Link]
Access Dallas 1-wire bus on your PC with simple and cheap hardware.
This project is based on Maxim’s application note: Using a UART to Implement a 1-Wire Bus Master
Onewire over UART - [Link]
This minimalistic board is packed with features and comes with an extensive ecosystem of documentation and firmware.
For the student (we are never too old) that wants to fast track his career as a professional firmware developer there is:
- a detailed getting started guide
- an Atmel AVR quick start guide, with tutorials and examples
- Recommend best practices
For the developer that wants to improve his game there is:
- A header to quickly connect different kinds of peripherals (GPIO, A/D, UART, SPI & I2C). Notice that each interface has it’s own +3V3 and GND pins to make wiring easier and also improves EMC.
- A full-featured CLI application to experiment with the connected device and verify that it works, before committing to a single line of C code.
- A firmware framework that lays the foundation so that you can quickly develop a new application.
- A Temp&Pressure Logger and Analog voltage Logger application that demonstrates how you can quickly develop your own custom logging application using the onboard AT45D DataFlash.
Atmel ATmega328P Scorpion Board - [Link]
by Patrick Hood-Daniel @ youtube.com:
In this video, I introduce the concept of I2C or TWI and explain the common use of the protocol and how to set it up. This is part one. Part two will delve into the circuit that we will use for the example.
I2C/TWI (Two Wire Interface) Tutorial - [Link]
This project embodies the concept of I2C bus standard. It signifies how important to know the I2C devices and how they will be integrated. There are a lot of innovation can be made using the standard and more people are attracted to get involve in the embedded world professionally or just as hobbyist. The number of I2C devices included in this project may develop new ideas and designs.
The design includes 8-Bit Microchip PIC18F14K22 microcontroller which serves as the master of the I2C bus communication principle. The PCA9547D device is an 8-channel I2C-bus multiplexer with reset that communicates with the I2C devices one at a time. The PCA9500 device is an 8-bit I/O expander with an on-board 2-kbit EEPROM that simplifies the connection of LCD to the multiplexer. The MCP9801-M/MS device is a 2-Wire High-Accuracy Temperature Sensor for temperature monitoring. The 24LC025/ST device is a 2.5V, 2 Kbit Addressable Serial EEPROM (Tape and Reel) with no WP pin for firmware application. The MCP3221A0T-I/OT and TC1321EOATR devices are both for data conversion. The MCP3221A0T-I/OT is a Low Power 12-Bit A/D Converter With I2C Interface and the TC1321EOATR device is a 10-Bit Digital-to-Analog Converter with Two-Wire Interface. The MPL115A1 device is Miniature I2C Digital Barometer for pressure sensing applications. The MCP79400-I/MS is a Battery-Backed I2C™ Real-Time Clock/Calendar with SRAM and Protected EEPROM for applications that includes time. The PCA9530D device is a 2-bit I2C-bus LED SMBus I/O expander optimized for dimming LEDs in 256 discrete steps for Red/Green/Blue (RGB) color mixing and backlight applications. The 2X16 LCD is for display and monitoring application.
The design is very versatile since it opens up ideas to innovate. It is an excellent project for embedded system application. There are a lot of student will be attracted to develop their own design.
Interfacing MCU to various I2C Devices XD - [Link]