On Arduino Due PWM Frequency

I just got myself a couple of Arduino Due boards. While they were released almost two years ago, I have not really got a chance to look at these until quite recently. Arduino Due is based on Atmel’s ATSAM3x8E 32-bit ARM Cortext-M3 processor. The processor core runs at 84 MHz, which is significantly faster than its 8-bit AVR counterpart ATmega328p which runs at 16 MHz. For an ATmega328p, the highest achievable PWM frequency is 8Mhz (square wave), so we should be able to generate much higher frequency signals on an Arduino Due. But how high can we go? Let’s find out.
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HP 8642B Teardown Pictures

In my last post, I showed my LED backlight mod of the HP 8642B synthesized signal generator. And during the process, I also showed some pictures of the A1 (keyboard and LCD) module and A2 (modulator) module alone with an intriguing Easter egg message in the firmware. In today’s post, I will do a full teardown of each module and take a closer look at what’s inside.
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HP 8642B Backlight Mod

If you take a look at the picture below, you may recognize immediately that it is a picture of an HP 8642B synthesized signal generator. But if you take a closer look, you probably will notice something different if you have ever used an HP 8642B before.
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A Four Channel Remote Control Using EnOcean Pi

In my last couple of blog posts, I did a brief overview of the EnOcean Pi sensor kit from Newark and demonstrated how to compile and run the example code using a Raspberry Pi. In this blog post, I will show a real world example – a four-channel remote control built using the EnOcean Pi in conjunction with the EnOcean pushbutton module.
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Compiling and Running EnOcean Sensor Kit Example Code

In my previous post, I took a quick look at the EnOcean sensor kit from Newark for Raspberry Pi and tested its basic functionalities using the Fhem home automation software. In this blog post, I will walk you through the process of compiling and running the example code that comes with the EnOcean Link library. While there are instructions on how to do this, some of the information is out-dated and hard to follow. So I will provide my own step-by-step instructions here.
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A Quick Overview of the EnOcean Pi and EnOcean Sensor Kit

I recently got the EnOcean Pi and EnOcean sensor kit from Newark. The sensor kit includes a temperature sensor module (STM330), a magnet contact transmitter module (STM320) and a pushbutton transmitter switch module (PTM210). The EnOcean Pi module is a receiver adapter board that connects directly to the popular Raspberry Pi. It is a gateway for handling the all the communications with the wirelessly connected sensors.
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Wavetek 907 Repair, YIG Oscillator Teardown

As I mentioned in my previous posting, there was an issue with my Wavetek 907 microwave frequency generator. While everything was fine during my initial testing, the frequency display is now stuck with an out-of-range display and the adjustable frequency range is limited to between around 6.9 Ghz to 7.9 Ghz (instead of all the way up to 11 Ghz). My initial suspicion was that the PTC heater inside the YIG-Gunn oscillator was malfunctioning. But as it turned out, it was something else.
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Wavetek 907 Signal Generator Teardown

Since I just got myself an HP 5350B microwave counter and I had fixed it up, I thought it would be great if I could get a SHF generator to test out the counter in the microwave range. So when I saw a super cheap Wavetek 907 for sale on eBay, I simply could not pass it up.
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DS3232 Clock Frequency Calibration

DS3232 is an extremely accurate RTC with a guaranteed accuracy of 2.5 ppm (0 °C to 40 °C), which translates into an error of just 80 seconds over the course of a year under the worst case scenario. I had done a few projects using this chip before (you can read about them here).
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HP 5350B OCXO Repair

Last time, I did a teardown of an HP 5350B microwave counter. And as I mentioned in my teardown, the oven-controlled crystal oscillator (OCXO) did not appear to be working as the OVEN indicator would not go off even after hours of use but the counter appeared fully functional otherwise. So I decided to disassemble the crystal oven and see if this problem can be fixed.
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HP 5350B Microwave Counter Teardown

Here is a teardown you do not see very often. I recently bought an HP 5350B 20 GHz microwave counter off eBay. HP 5350B uses harmonic heterodyne down-conversion technique to convert the microwave frequency into the range of its internal low frequency counter. It can measure frequencies from 10 Hz all the way up to 20 GHz via two separate inputs.
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MF 10A Analog Multimeter Teardown

Dave did an analog multimeter teardown in his latest episode. I have a Chinese made MF 10A multimeter bought back in the 90’s and thought I’d do a teardown to take a look at what is inside.
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An Old Tung-Sol Germanium Transistor

I recently bought a few old power transistors from eBay. These are PNP Tung-Sol germanium transistors. According to the date code (6326) these transistors were made back in 1963, long before I was born. The last time I actually used a germanium transistor was more than twenty years ago when I was learning to make transistor radios.
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Keithley 197 Teardown and Repair

A few days ago, I bought a Keithley 197 sold as “unknown working condition” on the cheap. The seller said that some of the keys on the meter were unresponsive. I figured that I’d try fixing it if I could. After all, these 5 ½ meters still fetch well over $100 on eBay and for a fraction of that price, I was willing to give it a shot.
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Server Moved to Linode

I just moved my site from my own server to linode‘s VPS hosting. So you should see some pretty significant performance improvement down the road.
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