Touch Weather Station using a DHT22 Sensor and a Raspberry Pi 3 with TKInter tests the new Raspberry Pi 3 board, by building a simple but useful project.

A few months back, the Raspberry Pi 3 board was released. It is a great new board because it now offers WiFi and Bluetooth connectivity out of the box! It uses a quad core processor which operates at 1.2Ghz and it has 1GB of RAM available. From the benchmarks I have seen, this board is at least 3 times faster than the original Raspberry Pi. It can run Linux and offers 40 GPIO pins for our projects. The impressive thing is its price. It costs around 40$ and was kind enough to send me a sample unit in order to test it and build projects with it.

Touch Weather Station using a DHT22 Sensor and a Raspberry Pi 3 with TKInter [Link]

A miniature persistence-of-vision board

front published an update of the board and firmware of their SMD POV display.

This device is simply 8 bright SMD LEDs and an AVR uC and makes use of the Persistence of Vision effect. You wave it about, and it writes messages in the air, with no wires, liquids or unpleasant bending! Some would say that it’s quite similar to magic. It’s a double-sided kitchen PCB (toner transfer) with a flower on the back. It has a single button; held for a second, it switches it on/off. When on, a quick click switches between a set of predefined messages. It runs off a CR2032 until the end of time.

A miniature persistence-of-vision board – [Link]

VHF Frequency Counter with PC Interface


Scott has published a new build:

This is the general idea behind how this frequency counter works. It’s so simple! It’s entirely digital, and needs very few passive components. sn74lv8154 is configured in 32-bit mode (by chaining together its two 16-bit counters, see the datasheet for details) and acts as the front-end directly taking in the measured frequency.

VHF Frequency Counter with PC Interface – [Link]

Withings GO activity tracker teardown


nick @ tears-down the Withings GO activity tracker.

First, we removed the battery. This is easy: you can simply open the back of the casing with the included tool or with a regular coin. The included battery turned out to be a Panasonic 3V CR2032 with a capacity of 225mAh. In other words, it could power a device consuming 225mA for one hour. According to the Withings GO product website, the battery can last up to 8 months, so simple math tells us that the tracker consumes only 43.4 microamps. With real life usage, that number will probably turn out a little higher, but even then it’s a very low-power device.

Withings GO activity tracker teardown – [Link]

Time Machine – A Smart Clock That Does What You Say Using Alexa Voice Service

With a controller and a seven segment display, showing the time is not a so special feature, but when this clock can listen to the user and do what they want, that’s what worth highlighting a “Time Machine”.

Analysing human voice and take action based on that is not so simple. That’s why using a ready made solution is needed.
Intelligent personal assistant (IPA) is a software designed to perform tasks specified by user voice instructions. Alexa from Amazon, Google Now and Siri from Apple are examples of intelligent personal assistant software.

Some IPAs are designed to be integrated within IoT devices and Alexa is one of them. Amazon has an intelligent cloud service that allows developers to voice-enable any connected product only using a microphone and speaker, it’s called Alexa Voice Service (AVS).

Nick Triantafillou in his project, “Time Machine” used AVS to take the voice command.
The project contains Raspberry Pi 3, 1.2″ 4-Digit 7-Segment Display, wireless speaker and a push button switch.


Nick followed the steps to enable Alexa Voice Service (AVS) for his Raspberry Pi 3 using this tutorial. To make the project more exciting he used IFTTT service so he can make any conditional action using Alexa’s voice orders with IFTTT.


To see the full instructions and details of getting all hardware to work with Raspberry, please go to the project page on

Nick demonstrates the project in the video below:

Public Release of ESP32 SoC The Big Brother Of ESP8266

It has been about one year since the announcement of ESP32 SoC and the beginning of its beta testing for some developers.

A Letter From Espressif Systems Announcing The ESP32 – Source: twitter

Last Month we covered the release of ESP-WROOM-32 module datasheet,  which promised that “New SDK features, tutorials and example applications will be released over the next few months.”.

The ESP-32 datasheet was released at the end of August. So let us discover the details of ESP-32 SoC.

ESP32 Connectivity

ESP32 is a single 2.4 GHz Wi-Fi and Bluetooth combo chip available in QFN48 (6×6 mm) package. The new chip supports 802.11 b/g/n/e/i protocols with a data-rate up to 150Mbps. The previous ESP8266EX SoC supports 802.11 b/g/n only.

The security is enhanced in ESP32 by supporting WPA/WPA2/WPA2-Enterprise/Wi-Fi Protected Setup (WPS), while ESP8266EX supports only WPA and WPA2.

ESP32 features a BT4.2 controller and host stack with Xtensa Dual-Core 32-bit LX6 microprocessors up to 240 MHz. Keep in mind that ESP8266 has single core and lacks a bluetooth transceiver.

ESP32 Peripherals

ESP32 Block Diagram
ESP32 Block Diagram

A lot of peripherals were added and enhanced. Up to 18-channel ADC with 12-bit resolution, two DAC channels with 8-bit resolution, 4 × SPI, 2 × I2S, 3 × UART and 2 × I2C.
ESP32 also features 1 host (SD/eMMC/SDIO), 1 slave (SDIO/SPI), Ethernet MAC interface with dedicated DMA and IEEE 1588 support, CAN 2.0, IR (TX/RX), Motor PWM and LED PWM with up to 16 channels.

Internal Sensors

Hall, 10 × touch and temperature sensors are internally available in ESP32 SoC.

Cryptographic Acceleration Hardware

Cryptographic acceleration hardware is for AES, HASH (SHA-2) library, RSA and ECC with Random Number Generator (RNG).


ESP32’s internal Memory units are:

  • 448 KBytes ROM for booting and core functions.
  • 520 KBytes on-chip SRAM for data and instruction.
  • 8 KBytes SRAM in RTC, which is called RTC FAST Memory and can be used for data storage and main CPU during RTC Boot from the deep-sleep mode.
  • 1 Kbit of EFUSE, of which 256 bits are used for the system (MAC address and chip configuration) and the remaining 768 bits are reserved for customer applications.

ESP32 runs user application from external memory just like ESP8266EX. ESP32 supports 4 x 16 MBytes of external QSPI Flash, while ESP8266EX supports up to 16 MBytes only. Could we have in the future a version of ESP32 with an internal ROM for user application like ESP8285 (the ESP8266 with internal ROM version) ?

Price And Development Tools

You can order ESP-32 SoC -the chip only not a module- for about 2.9$/unit from the Espressif store on Taobao.

Ai-Thinker, one of the third-party manufacturers of ESP modules, introduces ESP-3212 module on their Taobao store.


The demo board is currently for some beta users, and not yet officially available for public.


ESP32 Demo board - Image courtesy Ady
ESP32 Demo board – Image courtesy Ady

Further Reading

ESP32 Resources
ESP32 Forum
ESP32 SDK User Guide

LTC Design Note: Dual 9A, step-down μModule regulator with digital power system management


Jian Li, Yingyi Yan and Marvin Macairan have published a Design Note based on LTM4675 dual DC/DC regulator.

The LTM4675 is a dual 9A or single 18A step-down μModule (micromodule) DC/DC regulator featuring remote configurability and telemetry monitoring of power system management (PSM) parameters over PMBus—an open standard I2C-based digital interface protocol. Its 16mm × 11.9mm × 3.51mm BGA package includes analog control loops, precision mixed-signal circuitry, EEPROM, power MOSFETs, inductors, and supporting components. It features a wide 4.5V to 17V input voltage range, and a 0.5V to 5.5V output voltage range with ±0.5% DC accuracy over temperature. LTM4675’s power outputs can be digitally adjusted, margined, and powered up/down at programmable slew rates and sequencing delay times. Maximum turn-on time is 70ms. Telemetry read back parameters include VIN, IIN, VOUT, IOUT, temperature, running peak values, uptime, faults, and warnings. Current read back accuracy is ±2.5% at 9A load over temperature.

LTC Design Note: Dual 9A, step-down μModule regulator with digital power system management – [Link]

Tracespace Online Gerber Viewer (beta)


This particular PCB viewer takes your Gerber and drill files and gives you individual layer renders as well as very fancy renders of what your completed boards are going to look like.

The tracespace viewer accomplishes all this locally (nothing gets sent to any server!) by converting your files to SVGs. Thanks to the “Scalable” and “Vector” in “SVG”, the renders are easy to examine and quite accurate.

Tracespace Online Gerber Viewer (beta) – [Link]

How to Build a Class-D Power Amp


Cezar Chirila @ shows how to build a Class-D amplifier which has amazing efficiency.

What is a Class-D audio power amplifier? The answer could be just a sentence long: It is a switching amplifier. But in order to fully understand how one works, I need to teach you all its nooks and crannies.

How to Build a Class-D Power Amp – [Link]

Exploring Eagle CAD ULPs #1 – PickUp.ULP Select Components Both in Schematic And Layout


Welcome to the first post of the “Exploring Eagle CAD ULPs” series. Every week we will publish a new post about one useful ULPs in Eagle CAD.
“ULP” User Language Program is a plain text file which is written in a C­-like syntax and can be used to access the EAGLE data structures and to create a wide variety of output files, you can consider it like a plug-in for Eagle.

You can reach the posts published in this series using the following link.


When we work on schematic design, we always add parts here and there, adding a missed capacitor for a power pin of a regulator or a missed resistor for a data line and so on.
When we will generate the board file to start routing, we will find the parts scattered in the board.

The first rule in placing and routing in PCBs is to place connected components near to each other, but in the raw board file you will find every component located in a different place according to the order of adding them in the schematic.

This becomes very annoying in big designs. You need to gather the connected components manually, you will using MOVE tool for that. For example, to gather the components C9, C11, Y1 and R1 of a crystal connected to the MCU, you should run the following commands in the layout editor:


Some MCUs have up to 50 capacitors and resistors or more connected to them, so obviously gathering components manually is not the way.

Personally I was doing the gathering process manually until the day I told myself, SHOW tool can highlight the component or components (by selecting them using ctrl+SHOW tool) both in schematic and PCB editor, you should find a similar way.

When I googled about the problem I found an ULP (made by lorenznl) in a response of one of Element14 forum discussions “How can I select components booth in schematic and layout at the same time?”, it was exactly what I was looking forward.

To use this ULP, you must select a group of components using GROUP tool then run “PickUp.ULP” from the schematic editor. Now when you will go to the layout editor, you will find the components you grouped them in the schematic editor movable as a group in the layout editor.

The below GIF demonstrates how this ULP works.



You can download the ULP from here: PickUp_ulp

See you in next post in this series with another useful ULP.