Precision circuit monitors negative-supply threshold:
Using an IC (MAX971) that includes an open-drain comparator and a precision 1% voltage reference, this circuit monitors the magnitude of a negative supply voltage and provides a digital warning of fault conditions. To monitor multiple negative voltages, use the MAX974, which includes four comparators.
Thanks for the tip rsdio!
Xilinx has released version 13.1 of their ISE Design Suite. including a number of new features. This software is used to develop programs from Xilinx CPLD and FPGA products, including the CoolRunner-II chips found in our development boards. The suite includes the free Webpack ISE.
Note that this is a ~4 GB download. However, Xilinx is also mailing the software on a free DVD.
User guides and tutorials are available free from Xilinx.
Microchip’s MCP79411 general purpose I2C™Compatible real-time clock/calendar (RTCC) is highly integrated with nonvolatile memory and advanced features including a battery switchover circuit for backup power, a timestamp to log power failures and digital trimming for accuracy. It can use a low-cost 32.768 kHz crystal or other clock source and the chip operates over a supply range of 1.8 to 5.5 volts. Time can be tracked in either a 12-hour or 24-hour format with an AM/PM indicator and timing to the second, minute, hour, day of the week, day, month and year. As an interrupt or wakeup signal, a multifunction open drain output can be programmed as an alarm out or as a clock out that supports 4 selectable frequencies. In addition, non-volatile memory is included along with a unique ID in a locked section of EEPROM that is factory programmed with an EUI-48 MAC address.
According to the datasheet, the chip is available in the SOIC package and Microchip says samples are available.
This application note describes the build of a complete electronic watch using this chip.
Profmaad started a Ruby library for working with the Bus Pirate, source available on github.
Via the forum.
Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.
rsdio writes:
Why regulate the voltage from your supply when you really need a controlled current to drive an LED? Any regulator is less than 100% efficient, and the losses increase as more current is drawn. It looks like the circuit in this application note would allow you to skip the voltage regulator and thus avoid massive losses. You would still use a regulator for the µC part of the circuit where a steady voltage is needed, but the LEDs could be driven independently. Unfortunately, the circuit as shown has way too many parts, but I have a feeling that the basic idea can be used in a much smaller circuit after careful study. In the last several years, I’ve designed USB-powered boards with almost 200 LEDs, and I wish I had known about this technique to squeeze every last ounce of energy out of the limited 2.5 W USB supply.
This LED driver reference design drives a 700mA constant current to a single string of LEDs with forward voltages up to 60V. The design allows PWM dimming based on supply chopping. The input power supply is chopped on and off at 300Hz to 1kHz frequency to achieve LED brightness control. The driver uses a fixed-frequency boost converter, controlled by the MAX16834 LED driver. This unique reference design limits the input inrush current to negligible levels without compromising either the input or output filtering. Design schematics and test results are provided.
Thanks rsdio!
PyroElectro shows how to make NTSC video with a FPGA:
NTSC video is a standard that has been around almost as long as black and white TVs. It’s a true analog standard, but we can use digital FPGA signals to create NTSC. This tutorial shows you how to output simple NTSC video to your TV.
McZ ported it to a CoolRunner-II CPLD:
I was able to get it to compile with the XC2C256-6-VQ100 device. Anything smaller did not have enough resources. The original project was done with a Virtex FPGA. I did not do anything to the original vhd file which is one of the nice features of VHDL. All I had to do is create a new project, select the device and add the ntsc_TOP source to the project. Simple! Obviously the pinout changes.
Via the forum.
Seeed Studio is asking for help creating an open source radiation sensor, to help in the wake of the Japanese Tsunami earthquake.
Can open hardware community do something to help in this? Seeed Studio is now sourcing sensors, then assemble quick measurement tools, ship as many/fast as possible to Japan.
Since we have no previous experience with such device, your help is needed!
If you have experience in making such device, some quick questions:
1. What would be the right sensor for such detection? Will the education purpose GM tube work?
2. Any recommended peripheral circuits?
3. Does such Geiger counter needs special calibration? Or can we calibrate it with commercial device?
All creations will be open source and donated, thank you for helping out!
If you have a Chumby and want to experiment with computer vision concepts, check out ChumbyCV. It’s a simple Computer Vision framework and library for the Chumby embedded linux computer (Chumby One and beyond).
Check out EMGRobotics for additional information, videos, and all kinds of robot information.
This document from Xilinx could easily be titled “Everything You Always Wanted to Know About Xilinx CPLDs But Didn’t Know Where to Look.” Its the Xilinx CPLD Applications Handbook, featuring the CoolRunner-II and XC9500XL. It’s a 422 page compendium of application notes, hardware interfacing tips and specs that any Xilinx CPLD user will want to refer to on a continuing basis. From the basics of driving LEDs to designing your own smart card reader, it’s in here!
The handbook covers the family of CPLDs contained on our soon-to-be-released CPLD development boards!
Don’t forget to share your current project in the comments or the forum. This week our favorite project gets a free QFP protoboard.
Here’s a summary of major developments over the last week:
Next week will be busy:
We’re going to try a publishing schedule. No promises:
What are you hacking this week?
Flemming has a list of tips for PCB manufacturing at ITead. Seeed Studio uses the same PCB shop, so these tips apply to their Fusion board service too.
I do all my PCB production at ITead Studio the price is low and their published specs are nice, but there are some quirks that you need to be aware of to get good product.
Thanks Flemming! Via the contact form.
Here’s a design for a digitally controlled power supply:
I’ve built quite a few power supplies over the years; it’s an almost vital tool for electronics. It’s been my plan to built one which would drop the analog potentiometers in exchange for digital control with a microcontroller. There are many advantages to it as well as disadvantages but I believe it is worth the effort.
Thanks tempmj! Via the forum.
Our favorite tools have a new home on the wiki. Each week we’ll muse a bit about one of them. Have your own tool review? We’ll post that too!
Sometimes it’s the small things that bring you joy. That’s definitely the case with this spiffy little label maker. It does one thing, and it does it well: it prints labels.
We don’t sell anything, so we don’t printing shipping labels all day, but we do mail lots of PCBs and business stuff.
For a while we suffered inkjet labels, but less than half of them turned out. Out of total frustration we started trolling classifieds and auctions for a label maker. Brother was our preferred brand because it has some degree of Linux support. We went with the QL-550 because it was $35 at a business bankruptcy auction, but any model would have been fine.
Labels are quite expensive, probably 10 cents each, but the convenience is worth it for a business. You can save money buying loose rolls on eBay, but we haven’t run out yet. So far the included roll has lasted through a year of Free PCB Sundays and light business administration.
The included software is poor and you have to enter a serial number to download updates, but we do use it regularly. You can also use the label maker as a normal printer from any app, which is interesting when you forget to swap printers in Eagle.
We consider this one of our best investments ever, but that probably says more about how much we hated inkjet label sheets.
There’s more tools too.
Chris from PyroElectro was looking for a way to miniaturize his previous VGA test box to make it more suitable for portable use. He came up with this design for a Mini AV Test Box for portable testing of VGA displays and speakers.
His project fits a full fledged AV tester into a mint-tin can with minimal requirements for using it. The design features a PIC 16F84A and 555 timer. Nothing complex, just a quick RGB display pattern to determine whether a display’s 800×600 VGA functionality works, and a variable tone oscillator to check whether a speaker or pair of headphones are operational.
Source code in assembly, schematic and PCB Eagle files are provided.
Rob from the 43oh blog has posted his method to interface a 24LC32A serial EEPROM interface to the Launchpad. The 24LC32A is a 32Kb PROM with a 2 wire serial interface or I2C compatible, and since it can be clocked @400kHz @3.6V bit banging seemed like it would be easy. External pull up should be between 2k-10k. While the suggested value is ~2k for 400kHz, he used a 10k and reports it’s working fine.
The code is available here.
This circuit is a simple and economical interface for remote IC thermal sensors. The temperature sensor (MAX6576), an absolute temperature-to-period converter that integrates the sensor with the necessary signal electronics, connects to the receiver (a MAX9140 comparator) using a twisted-pair cable that carries power to and signals from the sensor.
Thanks rsdio!
tjtag is an open source WIFI router rescue utility by our friend tornado. It uses a parallel programming cable to write firmware back into a bricked router.
Now zoobab has ported jtjag to work with the Arduino as a programmer. If you don’t have a parallel port, just use an Arduino to rescue that router.
Thanks Tornado!
Today a parcel come in with lots of goodies from MDFLY. We are prototyping a lot so every useful gadget that helps us a lot. Follow below for a look at the jumper cables, resistor kits, and pogo pins in this order.
Continue reading “Parts: pogo pins, jumpers, resistor kits, more”
Atmel is presenting a free webinar on March 17, 2011 on AVR Studio 5. This one hour presentation will begin at 8:00 AM PDT and will cover the Visual Assist Solution Explorer project manager, the AVR Software Framework for AVR XMEGA and AVR UC3 and more including many example projects.
You can download your copy of AVR Studio 5 here.
Register now!
