Some dsPIC33E and PIC24E microcontrollers have an comparator module that can function as an op-amp [PDF]. The module can be used as a simple non-inverting amplifier by adding two external resistors, no external op-amp chip needed. The output can be read internally by the ADC module, or routed externally to use in your circuit.
Eldon Brown, WA0UWH, has been experimenting with a Parallax Propeller he received for Christmas. Being an avid amateur radio operator, Eldon decided to code up a low power radio beacon on the 30-Meter amateur radio band (10.10 to 10.15 MHz.) He wrote this simple program to generate very slow speed CW (Morse code) radio transmissions (a/k/a QRSS) using the Propeller.
At first he generated the desired signal directly from the Propeller with only the addition of a small attached wire antenna. He went on to modify the design to include a low pass filter (above right) to eliminate the PLL synthesizer phase jitter from the Propeller. He connected a proper outdoor antenna through the filter and is transmitting on 10.1387 MHz.
Check out Eldon’s WA0UWH website for the complete project log.
When using LEDs in projects it’s good to know what could cause their failure, and design your device to prevent it:
LEDs have a well-deserved reputation for high-efficiency operation, not to mention high reliability. Properly specified and implemented, LEDs should and do satisfy virtually every lighting application. Still, there are times when actual device lifetimes fall short of the specified ideal. LEDs are wide-bandgap semiconductor devices. As a result, they have far more complex and varied failure modes than the incumbent technologies. Unlike an incandescent lamp, where failure is fairly simple (the bulb produces light until the filament breaks), with an LED, the failure modes range from mechanical and electrical to material.
Via Electronics-Lab
Wortelsoft has a review of the Flower 2.2 protoboard shield for Arduino Mega. It has a unique solder pad that can be used with surface mount parts, and a via in each cluster of contacts can be used with through hole parts.
The Flower protoboard is a clever new design which makes it easy so combine SMT with throughole to save some board space on an Arduino proto shield. I missed the silk screen idicating the name / function of the pin. The price of the shield is on par with other protoshields on sale elsewhere. I hope elecfreaks will also make some single and double sided protoboard for none Arduino usage using the “flower” pads.
Via the contact form.
Better ADC resolution can be accomplished by oversampling two or more ADC readings and then averaging them. If you’re not satisfied with a microcontroller’s 10 bit ADC and need more resolution, check out this application note from Atmel.
Increasing the ADC resolution by one bit requires 4 ADC measurements. Four 10 bit readings are needed for one 11 bit reading. Similarly, the maximum bandwidth is reduced. If you go from 10 bit to 16 bit, the maximum bandwidth comes to 7600 Hz divided by 46 (i.e, 4096) – that’s only ~2 Hz.
We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service.
Would you like to start off 2012 with a free PCB? This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB.
You get unlimited free PCBs now – finish one and we’ll send you another!
Don’t forget there’s free PCBs three times every week:
Arhi received a mystery PCB with his last ITead PCB order:
TFT digital picture frame with in built Real-Time clock and thermometer
Designed by: Erick AubinI assume B1 is a big capacitor, something like 22000uF or similar (judging from the size), USB-BUB is some ft232 or similar usb 2 uart board, x1 is some 8 or 16 MHz xtal and X2 is 32768 kHz, U1 is probably some ATMEGA as J1 looks like AVR ICSP connector and Z1 is some 7805 or something … now, what mega should be there, what firmware, what kind of tft lcd … no idea … if you know a homepage for this project – share :D
If you recognize it, give us a shout in the comments, the forum, or the contact form.
Via the forum.
Resistive touch screens are pretty cheap, and make it easy to interface with device without placing a lot of buttons. This app note describes how to interface with 4, 5, and 8 wire resistive touch screens on your next project.
All analog touch screens consist of a ridged layer and a flexible layer with a separation layer between them. The flexible layer is exposed to the outside, towards the user. The inside surfaces of the ridged and flexible layers are coated with a resistive coating, usually ITO (indium tin oxide). When the flexible layer is pushed its conductive surface will make contact with the conductive surface of the ridged layer making an electrical connection between the two layers at the point of contact. Measurements are then made to determine the point of contact.
Happy New Year!
Thank you for reading the blog and being part of our community in 2011. We’re looking forward to more open hardware projects, more how-tos, more videos, more free PCBs, and more hacking in 2012.
Fans of tech history may want to read Dot-dash-diss: The gentleman hacker’s 1903 lulz. This article appears on the NewScientist website and reveals that wireless hacking dates back to the time of Marconi!
Any you thought you were onto something new with a walkie talkie on the frequency of the drive-thru order window…
H used an IC testing clip to make a simple adapter for programing ATmega microcontrollers on the fly. IC test clips are tools used to grip ICs and provide easy connection to the pins.
I’ve got a different use for it though. If you develop a circuit using an Atmega chip (like, say, a circuit you developed with an Arduino but have now moved to a custom board), reprogramming the chip is fiddly. The best way to make your circuit easily re-programmable is to build an ISP header onto your board – it’s just a 6-pin connector that lets you blast new programming onto the chip without removing it from the circuit.
Most of my little circuits don’t have room for the 6 pin connector though, and it’s a hassle to hook up the 6-pin programming connections when you’ll hopefully never have to reprogram the things anyway.
To program the chips on these boards you have to lever the chip out, stick it in a programmer and then stuff it back into the circuit board again. Not the most difficult thing to do, but it can get a bit fiddly, and it’s always a bit dangerous trying to lever the chip out without damaging the chip or the board. The test clip fits over all the pins you need access to for programming though.
Via Electronics-Lab.
This reference design shows how to drive long 1-Wire networks. 1-Wire is a communications protocol used by some Dallas/Maxim parts. The protocol uses only one wire for power, transmission, addressing, and synchronization.
This document describes a microcontroller-based 1-Wire master interface for reliable operation of small, medium size and large 1-Wire networks. This is accomplished using careful impedance matching, intelligent (software-controlled) active pullup, and slew-rate control. Software flow charts are included to assist the user in generating the correct 1-Wire timing for reset pulse, presence detect, write one, write zero and read time slots using any suitable microcontroller. Scope traces illustrate the timing performance of the driver as well as transmission line effects as they appear with long cables.
We think 1-Wire’s days are numbered because Maxim has discontinued most 1-Wire parts. Maybe if they didn’t prohibit 3rd-party slave devices it would have seen wider use…
Juan used his free 0.50mm Dangerous xQFP protoboard to get started with a MSP430F5510. The protoboard is designed to get you up and running with a new surface mount microcontroller.
We’re super proud of this board, it’s something we use all the time to develop our own projects. Currently available in 0.50mm, 0.65mm, and 0.80mm for $10.
If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.
Fcobcn posted pictures of his free Bus Pirate v4.0 PCB build.
If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.
Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.
Wingnut decided to port the AVR transistor tester to his Teensy 2.0 board. The transistor tester is a tool for identifying and measuring common discrete semiconductors and passive devices.
I decided to port the component tester (freely using Google Translate to get some sense of the comments) as my first hands-on tutorial, and managed to get it up and running this morning!
Have not exhaustively tested yet but it correctly identified known BJTs, Mosfets and Triacs from my parts bin.The hFE values seem to be a bit off on some scavenged BJTs. And on a couple of NMOS power fets, I had to transpose the leads before it was correctly recognized (otherwise identified as a capacitor on two of the pins).
Via the forum.
Will O’Brien developed this project allowing him to remotely start his car via an SMS sent to a jailbroken iPhone. The additional hardware involved is an Arduino, iPhone breakout board such as the PodBreakout Mini, 4x 10k resistors, 1x TIP120 and a 5 volt switching supply cell charger.
All the details, including source code and schematic are available on Will’s Biobug website.
Via MAKE.
Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday.
Don’t forget there’s free PCBs three times a every week:
Continue reading “Free PCB coupon via Facebook to 2 random commenters”
Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon:
Coming up:
What are you hacking this week?
Arhi posted pictures of his latest soldering iron driver build:
Here are the pictures of the populated board. Actually the DC driver is not populated as I’m not very interested in it and there’s no usb connector and D10, R40 as those are also only required for USB operation and I ain’t going to be using USB not even for bootloader, all debugging I’ll do trough serial and programming trough ICSP connector on board. The PIC18F2550 is not in the “stand” because I was still testing how analog side of things worked (works perfectly). Now I’ll go write some firmware to get this puppy running :)
Via the project log forum.
Circuitvalley posted a step by step guide to interfacing Nokia 1100 LCDs with a microcontroller.
Via the comments.
