About Circuit Cellar Staff

Circuit Cellar's editorial team comprises professional engineers, technical editors, and digital media specialists. You can reach the Editorial Department at editorial@circuitcellar.com, @circuitcellar, and facebook.com/circuitcellar

Probe a Circuit with the Power Off (EE Tip #14)

Imagine something is not working on your surface-mounted board, so you decide use your new oscilloscope. You take the probe scope in your right hand and put it on the microcontroller’s pin 23. Then, as you look at the scope’s screen, you inadvertently move your hand by 1 mm. Bingo!ComponentsDesk-iStock_000036102494Large

The scope probe is now right between pin 23 and pin 24, and you short-circuit two outputs. As a result, the microcontroller is dead and, because you’re unlucky, a couple of other chips are dead too. You just successfully learned Error 22.

Some years ago a potential customer brought me an expensive professional light control system he wanted to use. After 10 minutes of talking, I opened the equipment to see how it was built. My customer warned me to take care because he needed to use it for a show the next day. Of course, I said that he shouldn’t worry because I’m an engineer. I took my oscilloscope probe and did exactly what I said you shouldn’t do. Within 5 s, I short-circuited a 48-V line with a 3V3 regulated wire. Smoke and fire! I transformed each of the beautiful system’s 40 or so integrated circuits into dead silicon. Need I say my relationship with that customer was rather cold for a few weeks?

In a nutshell, don’t ever try to connect a probe on a fine-pitch component when the power is on. Switch everything off, solder a test wire where you need it to be, grab your probe on the wire end, ensure there isn’t a short circuit and then switch on the power. Alternatively, you can buy a couple of fine-pitch grabbers, expensive but useful, or a stand-off to maintain the probe in a precise position. But still don’t try to connect them to a powered board.—Robert Lacoste, CC25, 2013

PIC32MX1/2/5 Microcontrollers for Embedded Control & More

Microchip Technology’s new PIC32MX1/2/5 series enables a wide variety of applications, ranging from digital audio to general-purpose embedded control. The microcontroller series offers a robust peripheral set for a wide range of cost-sensitive applications that require complex code and higher feature integration.MicrochipPIC32MX125-starterkit

The microcontrollers feature:

  • Up to 83 DMIPS performance
  • Scalable memory options from 64/8-KB to 512/64-KB flash memory/RAM
  • Integrated CAN2.0B controllers with DeviceNet addressing support and programmable bit rates up to 1 Mbps, along with system RAM for storing up to 1024 messages in 32 buffers.
  •  Four SPI/I2S interfaces
  • A Parallel Master Port (PMP) and capacitive touch sensing hardware
  • A 10-bit, 1-Msps, 48-channel ADC
  • Full-speed USB 2.0 Device/Host/OTG peripheral
  • Four general-purpose direct memory access controllers (DMAs) and two dedicated DMAs on each CAN and USB module

 

Microchip’s MPLAB Harmony software development framework supports the MCUs. You can take advantage of Microchip’s software packages, such as Bluetooth audio development suites, Bluetooth Serial Port Profile library, audio equalizer filter libraries, various Decoders (including AAC, MP3, WMA and SBC), sample-rate conversion libraries, CAN2.0B PLIBs, USB stacks, and graphics libraries.

Microchip’s free MPLAB X IDE, the MPLAB XC32 compiler for PIC32, the MPLAB ICD3 in-circuit debugger, and the MPLAB REAL ICE in-circuit emulation system also support the series.

The PIC32MX1/2/5 Starter Kit costs $69. The new PIC32MX1/2/5 microcontrollers with the 40-MHz/66 DMIPS speed option are available in 64-pin TQFP and QFN packages and 100-pin TQFP packages. The 50-MHz/83 DMIPS speed option for this PIC32MX1/2/5 series is expected to be available starting in late January 2015. Pricing starts at $2.75 each, in 10,000-unit quantities.

 

Source: Microchip Technology

New Fully Differential Amplifiers (FDAs)

Texas Instruments has announced two new fully differential amplifiers (FDAs) intended to improve performance in radar and test and measurement equipment and wireless base stations. The LMH3401 and LMH5401 FDAs provide DC-coupled applications with high-quality AC performance to improve system capabilities. They offer a higher bandwidth and slew rate, as well as lower distortion than existing ADC drivers.LMH3401   LMH5401 PR graphic

The LMH3401 delivers 7 GHz of –3-dB bandwidth at 16-dB gain, a high slew rate of 18,000 V/µs, and low harmonic distortion of –77 dBc at 500 MHz. The LMH5401 can be configured for 6 dB of gain or more, delivering 6.2 GHz of -3 dB bandwidth at 12-dB gain.

The LMH3401 and LMH5401 are available in a 14-pin, 2.5-mm × 2.5-mm QFN package. The LMH3401 costs $8.95 and the LMH5401  coss $7.95 in 1,000-unit quantities.

Source: Texas Instruments

STMicro Reduces Time to Development with Open.MEMS Licensing

STMicroelectronics recently announced the launch of the Open.MEMS licensing program. Its purpose is to encourage broad use of its MEMS and sensors among open-community developers. Open.MEMS licensees can access free drivers, middleware, and application software, beginning with “sensor fusion for 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer, considered vital for many portable and wearable applications.”

STMicro’s STM32 Open Development platform supports Open.MEMS, which went live on November 11, 2014, and will continue to be expanded regularly with additional low-level drivers, middleware/libraries, and application-layer code.

 

2014 Year-End Notes

In every December issue, we like to take a look at where we’ve been and where we’re going. Since this is the final issue of the year, let’s review a few important notes about 2014 and the 2015 editorial schedule.

CIARCIA PURCHASES CIRCUIT CELLAR

In early October, Circuit Cellar’s founder Steve Ciarcia finalized a deal to purchase Circuit Cellar, audioXpress, Voice Coil, Loudspeaker Industry Sourcebook, and their respective websites, newsletters, and products from Netherlands-based Elektor International Media. After gaining international recognition for writing BYTE magazine’s “Ciarcia’s Circuit Cellar” column, Ciarcia launched Circuit Cellar magazine in 1988. Since then, he’s published hundreds of articles and editorials in the magazine.

Circuit Cellar founder Steve Ciarcia addresses the team Vermont

Circuit Cellar founder Steve Ciarcia addresses the team Vermont

WIZnet CONNECT THE MAGIC 2014 DESIGN CHALLENGE

In March 2014, engineers around the globe began working on innovative Internet of Things (IoT) design projects around WIZnet’s WIZ550io Ethernet controller module. In September, after a few weeks of judging, we announced the winners. Hans Peter Portner won First Prize for his Chimaera design, which is a touch-less, network-ready, polyphononic music controller.

Portner's Chimaera project

Portner’s Chimaera project

2015 EDITORIAL CALENDAR

Interested in publishing an article in a 2015 edition Circuit Cellar? Email a proposal or complete submission to editor@circuitcellar.com. Our 2015 editorial calendar is now live.