Again, with this meter I was going for simplicity. Sure, for perfectly accurate measurements you need to measure both the supply current and voltage but for this application and in the interests of keeping the energy meter simple and safe – only requiring a non-contact connection to your mains – I’ve decide to stick with a simple current measurement which gives you an estimate to within a couple of decimal points of a kilowatt hour.
This meter measures the supply current through each phase using a CT (current transformer) and then does a few calculations to give you the current, power, maximum power and kilowatt hours consumed for each phase.
Solar power has surged ahead in recent years, and access for the individual has grown accordingly. Not waiting around for a commercial alternative, Instructables user [taifur] has gone ahead and built himself a solar-powered Bluetooth headset.
Made almost completely of recycled components — reducing e-waste helps us all — only the 1 W flexible solar panel, voltage regulator, and the RN-52 Bluetooth module were purchased for this project. The base of the headset has been converted from [taifur]’s old wired one, meanwhile a salvaged boost converter, and charge controller — for a lithium-ion battery — form the power circuit. An Apple button makes an appearance alongside a control panel for a portable DVD player (of all things), and an MP4 player’s battery. Some careful recovery and reconfiguration work done, reassembly with a little assistance from the handyman’s secret weapon — duct tape — and gobs of hot glue bore a wireless fruit ready to receive the sun’s bounty.
Taking the initiative to go green using solar power– taken literally — could also result in getting into hydroponic gardening.
Over the past few years, I keep getting inquiries from people asking about how to measure the resonant frequency of these transducers, how to design horns, tune the length etc. I decided it was time to do a video about the entire process – hopefully I’ve covered everything relevant. If you check the YouTube description, I’ve put time links to each individual section of the video.
Previously, in part 1 of my blog posting Programming a 7-segment Display, using just Arduino digital pins (the hard way) we had demonstrated how to hook up a pair of 7-segment displays to an Arduino, treating each individual segment as a separate LED. There was a bit of tricky logic to translate each digit into the segments A, B, C, D, E, F, G plus additional logic to turn the digital pins on or off. Although I tried to code it as efficiently as possible, the logic may have been difficult to understand.
Also, constructing the project was fairly tedious, with dozens of resistors and hook-up wires.
Instead, lets do this the easy way. A typical MAX7219 module comprised of a single MAX7219 chip and eight 7-segment displays.
Vadim has posted a tutorial on how to use internal RTC of Stellaris and Tiva Launchpad boards in Energia IDE:
For those of you who still have one of those old Stellaris Launchpads, I’m going to show how to utilize one of its most useful features – real time clock – in a simple way. Actually, the Hibernation module is the same in the new Tiva Launchpad, so it’s supposed to work there as well.
[Juan Carlos Jiménez] has reverse engineered a router — specifically, a Huawei HG533. While that in itself may not sound substantial, what he has done is write a series of blog posts which can act as a great tutorial for anyone wanting to get started with sniffing hardware. Over the five part series, he walks through the details of identifying the hardware serial ports which open up the doors to the firmware and looking at what’s going on under the hood.
The first part deals with finding the one or several debug ports on the hardware and identifying the three important pins – Rx, Tx and GND. That’s when he shows novices his first trick – shining a flashlight from under the PCB to find the pins that have trace connections (most likely Rx and Tx), those that don’t have any connections (most likely CTS and DTR) and those that have connections to the copper pour planes (most likely VCC and GND). The Tx signal will be pulled up and transmitting data when the device is powered up, while the Rx signal will be floating, making it easy to identify them. Finding the Baud rate, though, will require either a logic analyser, or you’ll have to play a bit of a guessing game.
Once you have access to the serial port and know its baud rate, it’s time to hook it up to your computer and use any one of the several ways of looking at what’s coming out of there — minicom, PuTTY or TeraTerm, for example. With access to the devices CLI, and some luck with finding credentials to log in if required, things start getting interesting.
Over the next part, he discusses how to follow the data paths, in this case, looking at the SPI signals between the main processor and the flash memory, and explaining how to use the logic analyser effectively and decode the information it captures. Moving further, he shows how you can hook up a USB to SPI bridge, connect it to the flash memory, take a memory dump of the firmware and read the extracted data. He wraps it up by digging in to the firmware and trying to glean some useful information.
It’s a great series and the detailed analysis he does of this particular piece of hardware, along with providing a lot of general tips, makes it a perfect starting point for those who need some help when getting started on debugging hardware.