App note: DC-to-DC design guide

DC-DC converter design guide from Vishay. Link here (PDF)

Manufacturers of electronic systems that require power conversion are faced with the need for higher-density dc-to-dc converters that perform more efficiently, within a smaller footprint, and at lower cost despite increasing output loads. To meet these demands, Siliconix has combined advanced TrenchFET and PWM-optimized process technologies, along with innovative new packages, to provide:
– lowest on-resistance for minimum power dissipation
– lowest gate charge for minimum switching losses
– dV/dt shoot-through immunity
– improved thermal management

App note: Torque recommendations for TO-220 devices

App note from Vishay on the impact of torque on thermal resistance of TO-220 devices. Link here (PDF)

When the TO-220 was first introduced, most applications required something less than the full power handling capabilities of this package. Hence, the TO-220 is almost taken for granted in terms of its excellent power handling capacity and ruggedness. Today, however, advances in semiconductor technologies are bringing application demands closer to the TO-220’s capabilities, so an understanding of these is more relevant than ever.

DIY 18650 Powerwall with onboard BMS

A DIY 18650 Powerwall with onboard BMS @ openhardware.co.za

While I cannot afford a Tesla PowerWall, I’ve spent some time drawing up a PCB to house 7x 18650 cells in series. Each board has onboard Battery Management:
*Overvoltage Protection (per cell)
*Undervoltage Protection (per cell)
*Balance Charging
*Overcurrent Protection
*Main pack Fuse

The design files are available on GitHub.

The core memory inside a Saturn V rocket’s computer

A closer look at an LVDC core memory module:

The Launch Vehicle Digital Computer (LVDC) had a key role in the Apollo Moon mission, guiding and controlling the Saturn V rocket. Like most computers of the era, it used core memory, storing data in tiny magnetic cores. In this article, I take a close look at an LVDC core memory module from Steve Jurvetson’s collection. This memory module was technologically advanced for the mid-1960s, using surface-mount components, hybrid modules, and flexible connectors that made it an order of magnitude smaller and lighter than mainframe core memories.2 Even so, this memory stored just 4096 words of 26 bits.

See the full post on Ken Shirriff’s blog.

Building a Raspberry Pi stratum 1 NTP server

A how-to on building a Raspberry Pi stratum 1 NTP server:

So this article is going to be my notes on how I built one using a cheap GPS module off eBay as the reference time source and a Raspberry Pi. (a 2B in this case, but hopefully the differences for newer models will be minor; if there are any, they’re probably around the behavior of the serial port since I think things changed on the Pi3 with bluetooth support?)

See the full post on The Life of Kenneth blog.

Build a DMX FeatherWing to control lights with a Feather M0

Glen Akins writes:

This project uses an Adafruit Feather M0 Basic Proto board to control a group of Color Kinetics or other RGB light fixtures using the DMX-512 protocol. We’ll build a DMX-512 interface FeatherWing then connect it to the Feather M0 using a Particle Ethernet FeatherWing. Once the hardware is built and assembled, we’ll write software with a web-based GUI to generate RGB lighting effects and control the attached RGB lights using the DMX protocol. By modifying the software on the Feather M0, different effects can be generated and added to the web-based GUI.

Project info at bikerglen.com.

Sinilink WIFI-USB mobile remote controller

Peter Scargill blogged about his AliExpress Sinilink WIFI USB controller project:

So here’s a thing – I had this all set up and working perfectly with Tasmota on my WiFi – then plugged the unit (USB male end) into a USB3 connector – and it immediately lost the lot – well, the settings, not Tasmota – I had to go back to using my mobile phone as an access point and re-enter the info. That’s annoying but the reset after USB3 plugin might be related to somehow triggering the “normal” Tasmota device recovery, which indeed does a “factory reset”. So what I did next after advice from subscriber “sfromis”, was to use “SetOption65 1” in Tasmota console (which is a non-volatile setting) and I’ve had no trouble since – on the same USB3 hub.

More details on Scargill’s Tech Blog.

Check out the video after the break.

Continue reading “Sinilink WIFI-USB mobile remote controller”

App note: USB hardware and PCB guidelines using STM32 MCUs

Peripheral USB on STM32 MCUs app note from STMicroelectronics. Link here (PDF)

STM32 microcontrollers include a group of products embedding a USB (Universal Serial Bus) peripheral. Full-speed and high-speed operations are provided through embedded and/or external PHYs (physical layers of the open system interconnection model).

This application note gives an overview of the USB peripherals implemented on STM32 MCUs, and provides hardware guidelines for PCB design, to ensure electrical compliance with the USB standards.

App note: USB Type-C™ power delivery using STM32xx series MCUs and STM32xxx series MPUs

Guideline from STMicroelectronics on the basics of the two new USB Type-C™ and USB Power-Delivery standards. Link here (PDF)

This new reversible USB Type-C™ connector makes plug insertion more user friendly. The technology offers a single platform connector carrying all the necessary data. Using the power delivery protocol, it allows negotiation of up to 100 W power delivery to supply or charge equipment connected to a USB port, the objective being fewer cables and connectors, as well as universal chargers.

The USB Type-C™ connector provides native support of up to 15 W (5 V @ 3 A), extendable to 100 W (up to 20 V @ 5 A) with the optional USB Power Delivery feature.

Tutorial: Maximum clock Frequency for Kinetis using MCUXpresso clock tools

Erich Styger writes, “This tutorial is about how to use the NXP MCUXpresso Clock configuration and configure the board to the maximum clock frequency of 120 MHz. The same steps apply to many other boards, including the FRDM-K22F one. The tinyK22 has the K22FN512 ARM Cortex-M4F on it which runs up to 120 MHz. It is the same processor as the one on the FRDM-K22F.”

More details at mcuoneclipse.com.

Full Arduino code for poultry egg incubator with humidity sensor

A DIY Arduino-based poultry egg incubator with humidity sensor @ reuk.co.uk. Neil writes:

This device makes use of an always on motor which turns the eggs six full turns every 24 hours. Many of our other incubators have motors which have to be set up to run for a certain length of time a certain number of times per day, but the code for these is either specific to a particular motor or far more complicated (but of course more flexible) if the end-user of the incubator is to set these timings.
This device makes use of a DS18b20 digital temperature sensor, a 1602 LCD display module, a DHT11 humidity sensor, and is based around an Arduino Pro Mini, together with some relays, resistors, buttons, terminals, and other components available everywhere – easily salvaged from old and broken electronics even.

See project info and the full source code on REUK blog.

Raspberry Pi Controlled DC Load

Dr. Scott M. Baker has published a new build:

In this video I build a DC Load that’s controlled by a raspberry pi. I’ve built dc loads before, but this time I decided to up the goal to supporting 100w (it actually handled 200w) using three mosfets instead of one. I drive it with a DAC and read back the actual state using an ADC. The CPU board is a raspberry pi, and I have a VFD, encoder, and some buttons for control. It also has a web UI.

Project info at smbaker.com.

Check out the video after the break.

Continue reading “Raspberry Pi Controlled DC Load”

Building a better bit-bang UART – picoUART

Ralph Doncaster writes, ” The screen shot above is from picoUART running on an ATtiny13, at a baud rate of 230.4kbps. The new UART has several improvements over my old code. To understand the improvements, it helps to understand how an asynchronous serial TTL UART works first. Most embedded systems use 81N communication, which means 8 data bits, 1 stop bit, and no parity. Each frame begins with a low start bit, so the total frame is 1 start bit + 8 data bits + 1 stop bit for a total of 10 bits. Frames can be sent back-to-back with no idle time between them. The data is sent at a fixed baud rate, and when either the receiver or transmitter varies from the chosen baud rate, errors can occur.

See the full post on Nerd Ralph blog.

App note: Low ESR tantalum capacitors make a difference in circuit designs

App note from Vishay about how ESR in tatalum capacitors affect circuit performance. Link here (PDF)

When choosing a capacitor for any application, there are a few key characteristics that must be understood in order to analyze its suitability for the circuit. In a simple capacitor equivalent circuit model, there are three key characteristics that affect circuit performance: capacitance, equivalent series resistance (ESR), and inductance. The magnitude of these elements and how they change over temperature, frequency, and applied voltage are different for each capacitor technology.

App note: The benefit of using a three sense pin design on battery

App note from Vishay about correcting error when reading current on small valued shunt resistor using third pin. Link here (PDF)

The low values of battery shunts being produced today necessitate the use of precision analog to digital converters (ADCs) to interpret the voltage drop across the shunt’s element. Many of these precision ADCs require the sense pins to be within a certain voltage range of the ADC’s analog ground reference input.

App note: Bad block information introduction

App note from Macronix all about NAND flash bad blocks management. Link here (PDF)

Today, NAND flash is used in many fields, such as consumer, industrial, and automotive. Compared with NOR flash, NAND flash has the advantage of availability at higher densities and lower cost per bit. However, NAND flash has the disadvantage of requiring system management of bad blocks, while NOR flash does not. This application note describes how Macronix marks bad blocks in NAND flash and recommends the creation and usage of a bad block table to properly manage bad blocks.

App note: Enhancing system security with Macronix(TM) flash

Technical note from Macronix about built-in and hardware security strategies on their flash memories. Link here (PDF)

Attacks on a system typically alter or copy the content of the Flash image for three primary reasons, which are to:

  • operate the system in an unauthorized manner with the purpose of committing fraud against the user or service provider.
  • disrupt the functionality of many systems through a denial of service.
  • reverse-engineer the system in order to clone its data/code or to exploit its security weaknesses.

To achieve the above goals, both hardware and software skills are needed. The attack may come from direct tampering of a single system or from software spread through viruses in connected devices. The systems that more frequently have to deal with security are those connected to payment/billing services such as Set-Top Box, mobile devices (such as smart phones) and metering devices.