A microcontroller comes with a limited number of input/output lines. If you need an additional 8-bit port in your project without replacing the microcontroller, MCO23008 might be a good choice. It is an I2C compatible port expander and provide eight bidirectional I/O lines for I2C bus. The following tutorial describes the functioning of MCP23008 and its interface with a 8-pin microcontroller like PIC12F683.
Expand the I/O capability of your microcontroller with MCP23008 – [Link]
For a long time, I have been trying to find the cheapest and easiest way to control electronic devices wirelessly using a computer. It can open up a lot of possibilities. For example, you could build a radio controlled relay board, and control it from your computer. You could even control the board with a “small” computer such as an Arduino (or any microcontroller for that matter). If your Arduino has an Ethernet shield, you could use it as a Web server and control your relay board from anywhere in the world (as long as you have access to the Internet of course). There are many things that you could do without creating a mess with wires. I am mainly interested in this because I need a computer controlled wireless robot. A little background -
Computer Controlled Wireless Robot Build – [Link]
Turn off the Heater behind Me… [via]
Ed Nauman had a bad habit of leaving his workshop at night without turning off the heater. His wife would get up in the morning and find – to her consternation – the workshop was plenty toasty. In the interest of keeping peace in his household, Ed decided to create a gadget that would save the energy spent through forgetfulness. He knew he could buy an off-the-shelf solution, but as he says, “Where’s the fun in that?” Instead, Ed turned to the world of thermostats and microcontrollers.
Turn off the Heater behind Me – [Link]
It is a very simple data logger project based on PIC12F683 microcontroller. The microcontroller reads temperature values from a temperature sensor on a regular interval basis and stores them into its internal EEPROM memory. The recorded temperatures can be later transferred to a PC through serial interface. I originally published this project on electronics-lab.com last summer. I thought this could be a very good learning project for beginners, and so I am posting it here for Embedded Lab’s readers too.
A Beginner’s data logger project using PIC12F683 microcontroller – [Link]
Microchip has announced an expansion of its 8-bit segmented LCD microcontroller (MCU) family with five new devices—the PIC16LF1902/3/4/6/7 (PIC16LF190X) MCUs. The PIC16LF190X family supports many general-purpose applications and enables the implementation of LCD into low-power and cost-sensitive designs, such as security tokens, smart cards, medical devices, home appliances, key fobs or any application involving a segmented LCD. [via]
Microchip introduces PIC16LF190X 8-bit PIC® MCUs with integrated LCD control – [Link]
MOSFET transistors are excellent choice for driving high current devices such as motors or high power RGB LEDs. They offer very low switching resistance and very small heat dissipation compared to bipolar transistors. This guide is designed to explain how to drive P-Channel MOSFETs with a microcontroller such as PIC or ATMEGA.
Driving P-Channel MOSFETs with a Microcontroller – [Link]
Texas Instruments has launched a floating-point microcontroller (MCU) for operation under extreme temperature conditions from -55 °C to 210 °C, which it says is an industry first and exceeds the traditional 150 °C limit for high-temperature semiconductors devices.
Floating-point MCU operates at up to 210 C - [Link]
Riley Porter shows you how easy it is to replace a blown Atmel chip (the microcontroller heart of the Arduino) and to flash the Arduino software onto the new chip. For a few bucks and about 15 minutes of work, you can have your Arduino board back in business. [via]
Arduino – Replace and Re-Flash a Blown Microcontroller Chip – [Link]
Jon Chandler at Digital DIY offers these Commandments for using PICs. They’re not just applicable to PICs, however — these tips hold true for most microcontrollers and are good to keep in mind. He writes: [via]
1. All VSS and VDD pins on the chip must be connected.
Multiple pins are not put there for your convenience. They must all be connected for the chip to work properly. In the picture below, the VDD pins 11 and 32 must be connected to V+ and VSS pins 12 and 31 connected to ground.
2. Bypass caps of 0.1 micro-farad are to be installed across VDD and VSS as close to the chip as possible.
Bypass caps must be used regardless of any other capacitors in the power supply circuit. These may appear insignificant compared to large filter capacitors or capacitors used for the voltage regulator, but they must be used.
3. /MCLR must be pulled to VDD with a 10k resistor or explicitly disabled in code as Graham has explained.
A floating /MCLR pin may lead to intermittent operation, if the chip operates at all.
[editors note: on a PIC, the /MCLR pin is used to clear flash memory for reprogramming. Failure to tie it high or disable it in software can result in PIC amnesia]
4. Ensure that multiplexed port pins are correctly set up.
Many port pins can have multiple functions depending on how the PIC is configured. When using these pins, ensure that the desired function is enabled. Most notable are pins with analog functions, which often default to the analog state. When planning to use these pins for digital functions, such as driving an LED or reading a switch, the digital function must be specified.
5. If using a development board, verify the purpose and connection of jumpers and accessories on the board, and understand the effect these may have on your circuit.
For example, if the development board has a pot connected to one of the analog inputs, your sensor input will be inaccurate or not seen at all. Digital inputs may never change if the pot is rotated all the way to one end.
6. The first programming step is a blinking LED program.
Trivial and silly, yes. It verifies that the power supply is working, the chip is running, and that the programmer can actually program the chip. If the LED flash rate is set to 1 second, it’s also easy to verify that the clock is operating at the right frequency.
Commandments for Using PICs – [Link]