App note: Implement high-speed RS-485 application with i.MX RT based on NXP SDK

App note from NXP link here (PDF)

This application note describes how to implement RS-485 communication with NXP i.MX RT series EVK, and how to design software based on NXP MCUXpresso SDK. For high-speed RS-485 bus, normally the baud rate is up to 5 Mbps; the interrupt and software polling mode is not practical in such a scenario. DMA and other mechanisms must be adopted based on SDK API.

Automated weather satellite ground station

Here’s an automated weather satellite ground station project from Nootropicdesign, that is available on Github:

This project will show you how to create a fully automated ground station that will receive and decode NOAA weather satellite images and upload them to your own website served from an Amazon AWS S3 bucket. With this project you don’t need your own server or have to run your own website infrastructure. Have a look at my AWS site that is updated automatically all day long.

See the full project writeup on the Project Lab blog.

Building your own Mini flight recorder

Pinko designed and built his own mini flight recorder:

For a while a wanted to make my own flight recorder similar to the commercial altimeters but with my own requirements for functionality. In addition it needed to be visually appealing and functional in the same time … After some thinking about the design and functionality the idea for the MINI FLIGHT RECORDER was developed in my mind and I set myself to work.

See the full post on ExRockets Blog.

Wireless quiz / game buzzers

An Arduino based remote buzzer project by Flute Systems:

Base station uses an Arduino Pro Mini 5V. The reason for having 5V in this circuit is the TM1637 7-segment display. We’re using a 5V active buzzer module, two wires – signal and ground. On the left are the Adafruit PowerBoost 1000C for 5V and the green Pololu switch mode voltage regulator board for 3.3V for the radio module. The Base Station runs for ~5 hours off a 2000 mAh LiPo battery.

See the full post on Flute Systems blog.

Building a USB-C PD power hub

A detailed instructions of how to build a USB-C PD power hub @

About a month ago, I showed you how to create a USB power hub using a DC power adaptor like this. One of the suggestions was to use USB type C as the power source and in this post, we will learn how to do just that.

More details on BnBe Practical Electronic blog.

Check out the video after the break.

Continue reading “Building a USB-C PD power hub”

#FreePCB via Twitter to 2 random RTs

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

App note: Battery Fuel Gauging LSI [Smart LiB Gauge] for 1-Cell Lithium-ion/Polymer with LC709204F

App note from ON Semiconductor on their Smart Fuel gauge LC709204F. Link here (PDF)

LC709204F is a Fuel Gauge for 1−Cell Lithium−ion/ Polymer batteries. It is a part of our Smart LiB Gauge family of Fuel Gauges which measure the battery RSOC (Relative State Of Charge) using its unique algorithm called HG−CVR2. The HG−CVR2 algorithm provides accurate RSOC information even under unstable conditions (e.g. changes of battery; temperature, loading, aging and self−discharge).

Automatically re-connecting low-voltage cut-outs for 12 and 24 volt battery systems

KA7OEI writes:

In a previous post I described a simple circuit that provided a low-voltage cut-out that could be used in a battery-operated system – see the article “A latching low-voltage disconnect for 12 volt lead-acid and lithium batteries”. That circuit – intended mostly for lithium-based batteries – required manual intervention to “reset” the device, intended for those situations where you wanted to provide manual intervention in resetting the circuit to prevent causing harm to the battery – and maybe the gear connected to it.
This circuit is different from that described in the link above, intended mostly for lead-acid based systems where an automatic reconnect of the battery is required upon application of charge current.

More details on KA7OEI’s blog.

Bus Pirate “Ultra” HDL moves from simulation to real hardware

Latest simulation of Bus Pirate Ultra HDL

The HDL is complete enough to start testing on real hardware. This update puts almost every feature under control of the state machine in the FPGA so commands can be pipelined with repeatable precision. Commands (write/read SPI, set/clear pin, measure voltage, update PWM, enable pull-up resistors, etc) are pushed into a FIFO buffer using a 17bit command/data protocol inspired by the interface of ST7789-based LCDs. When the state machine is enabled the commands are processed in one continuous stream.

Verilog HDL for the FPGA is on github, the latest updates are currently on the command-data-refactor branch. A synthesized version of the bitstream is in the forum.

giggiu16 has already build a v1d. There are a few more boards to give away, if you’d like one please message Ian in the forum.

Homemade injection transformer for PSU loop analysis

Adil Malik made a DIY injection transformer for PSU loop analysis:

Recently, I have been designing some SMPS and required some hardware to measure the actual loop response of the complete converters. People familiar with this area will probably know this can be done breaking the feedback loop of the converter and injecting a small AC signal and measuring the loop response at the output of the converter. However, such a measurement requires a mechanism to inject this signal differential across a small resistor inline with the normal feedback network. Unfortunately, as most signal generators are ground referenced we need special hardware to convert this output to a floating output.

See the full post on DIY projects of an EE student blog.

Nano controlled step attenuator

VE3POA writes:

DuWayne KV4QB, has done a Step Attenuator project and was kind enough to give me a board he designed for it at FDIM this year. So, I will not reinvent the wheel here and follow his design. Thank you DuWayne. Here’s a link to his blog where you can read not only about his attenuator project but other great things he has done.
As is with DuWayne’s project, I’ll use 2 pe4302 boards connected in series with the control lines in parallel. This will mean that the attenuator steps will be in 1dB increments which is fine for anything I’ll require. Max power input is +24dbm which is again fine for my purposes.

More details on this blog At the Electronic’s Workbench of VE3POA.

Building a Power-over-Ethernet (PoE) power supply using a DPS5005 module

Dr. Scott M. Baker has designed and built a PoE-powered lab power supply using a DPS5005 and custom PoE board:

The DPS5005 is a DC-DC converter. It can accept an input voltage from 0 to about 55 volts or so, and will regulate an output voltage up to about 1 volt below the input. This version is good to 5 amps, but there are other versions of this supply that will do as little as 30V / 2A and as much as 50V / 20A. 50V 5A seems like a good sweet spot. Since it is a DC-DC converter, you have to have a DC source to drive it. A lot of people use a 48V power brick, as they are commonly available.

Project info at

Check out the video after the break.

Continue reading “Building a Power-over-Ethernet (PoE) power supply using a DPS5005 module”

An ATmega brushless sensorless motor driver v02

Davide Gironi has posted an update on his ATmega brushless sensorless motor driver project we covered previously:

Brushless electric motor (BLDC motors) are synchronous motors that are powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor.

See the full post on his blog here.

Check out the video after the break.

Continue reading “An ATmega brushless sensorless motor driver v02”

App note: Assembly guidelines for QFN (quad flat no-lead) and SON (small outline no-lead) packages

NXP’s app note about the internals and how to’s footprint design and solder their leadless dual and quad flat packages. Link here (PDF)

The small outline no-lead (SON)/quad flat no-lead (QFN) is a small size, lead-less plastic package with a low profile, moderate thermal dissipation, and good electrical performance. It is a surface mount package with metallized terminal pads located at the bottom surface of the package. SON have terminal pads along two opposite edges of the package versus QFN with terminal pads along the four edges of the bottom surface. SON is sometimes also referred as DFN: Dual flat no-lead package.