Jon Titus Blog

I breadboarded a microphone pre-amplifier circuit and it worked well until I added a circuit that used the audio output to drive an LED bar-graph display. Now, as the LEDs turned on or off, I could hear a click on the audio output. The audio and bar-graph circuits had plenty of decoupling capacitors, and I had used short connections, so coupling of the digital switching signal into the audio circuit seemed unlikely. My wife got tired of hearing me repeat "Test 1 2 3, test 1 2 3..," so I disconnected the microphone's output signal and fed the preamp directly with a low-frequency triangular wave that exercised the bar-graph display. Now I could hear the clicks without talking. Still I couldn't find their source.

But I had reviewed only the audio portion of the circuit and overlooked the +5V power for the LEDs that also supplied the bias current for the electre...Read More

Ed Sutter, the fellow who created MicroMonitor (uMon), an open-source embedded-system boot platform, sent me a note about his newest software, uCon, an embedded system console. Although many people think of serial ports as old fashioned, or even dead, those involved with embedded systems consider them much alive and useful.

To help developers take better advantage of serial ports, Ed's uCon acts like a terminal emulator that also works with remote networked computers, or "backends," to let them connect with a development system or prototype as a telnet or ssh client.

According to Sutter, uCon can operate as a telnet server on a host PC and then let remote clients connect to the PC and virtually connect to the same COM port that the local uCon session has connected to. This technique lets a developer or engineer work locally with a development system thro...Read More

An old economist gave some sage advice to a young grad student. "Son," he said, "give people numbers and dates, but never both at the same time." Information from many manufacturers must come from economists-turned-marketers because it often lacks important details.

Here's a case in point, with names removed to protect the guilty. I received a press release about new measurement devices. The release contained almost as much information about the company as about the new products. And the release came with no link to a product data sheet and no block diagram or photograph.

I asked for and received a link to a 2-page data sheet, but it lacked critical information such as the size and voltage of the battery used as an optional power source. Although the data sheet explained users can "configure" the device in several ways, it doesn't ex...Read More

I started to work with some new FPGA-design software that seemed to take a long time to "build" a simple LED-flasher demonstration project. I let it run for about 45 minutes while I answered emails and had a conference call.

When I took another look, I saw something flash in the corner of the software's display area, but it appeared only briefly every 15 seconds or so. That made it impossible to see what the short message said. The message also appeared superimposed on other information, which increased the difficulty to read it.

That's when I thought about using my camcorder to record the display so I could play it back and see what the message said. I recorded about 15 seconds of video, loaded the video into my iMac's iMovie software and slowly scanned through the frames. Then I saw the brief superimposed image of "Scanning JTag ports..."...Read More

In mid December 2009, headlines such as "Insurgents Hack U.S. Drones" and "Pentagon: Insurgents Intercepted Drone Spy Videos," appeared in newspapers and on Web sites. Stories suggested US military people knew others could intercept the video streams from unmanned aerial vehicles (UAVs) and view them. Apparently insurgents in Iraq--perhaps with help from Iranians--used the SkyGrabber software that, according to the SkySoftware Web site, "... accepts free to air (FTA) satellite data (movie, music, pictures) and saves information in your hard disk. So, you'll get new movie, best music and funny pictures for free." You'll need a satellite receiver or dish-TV system to get the signals. The software costs 21 Euros, or about $US 30. Sounds like a bargain.

Today, developers must create a complete security plan for a new product from the outset. Th...Read More

I hesitate to guess how many 8051-based MCUs go into products every day. This MCU architecture lives on in many forms. Silicon Labs has good news for 8051 aficionados. The latest low-power C8051F91x/0x MCUs can greatly increase battery life in RFID tags, remote sensors, healthcare devices, wireless controls, and other power-sensitive equipment. According to the company's 14 December 2009 announcement, these MCUs offer the lowest active-mode current at 160 μA/MHz. Current drops to 300 nA in sleep mode (with an active real-time clock and brown-out-detect circuit) or to 10 nA without these circuit powered.

Silicon Labs C8051F912 development kit ($US 99).

When designers look at low-power sleep or standby modes for MCUs, they might forget to also determ...Read More

A recent announcement explained that Essensium, a Belgian supplier of system-on-a-chip ICs joined the Wavenis Open Standard Alliance (Wavenis-OSA). I hadn't heard of Wavenis, so I investigated. A company called Coronis developed the Wavenis technology for low-power long-distance wireless communications between machines such as remote monitors and controllers. In June 2008, Coronis gave the Wavenis specs to the Wavenis-OSA that now manages standardization activities for the royalty-free technology. The largest Wavenis network covers 100,000 nodes and several million sub-GHz RF transceivers now operate throughout the world. (Technically, the core Wavenis technology is royalty free. Companies can license Wavenis IP that goes beyond the MAC and PHY layers.)

You can find the Wavenis OSA at: ...Read More

Yes, you can wear the eZ430-Chronos development kit Texas Instruments introduced on November 23, 2009. The kit looks like, and works like, a sports watch that includes functions for temperature and altitude, and by using an external wireless sensor, heart rate, distance, speed, and calories burned. Users also can take advantage of the built-in RF link to control external actions--such as change PowerPoint slides or operate remote equipment via buttons on the watch case. The eZ430-Chronos costs only $US 49, so even if you want only a neat sports watch, this product looks like a steal. (Order the eZ430-Chronos-915, the 915-MHz version--from the TI Store at www.ti-estore.com. The eZ430-Chronos comes in versions for the 433-, 868- and 915-MHz bands.) For general information and links to hardware and software, visit: ...Read More