App note: Ambient lighting design utilizing RGB LEDs


App note from OSRAM on using RGB LEDs or their MULTILED® for automotive interior lighting. Link here (PDF)

This application note describes the advantages and challenges of utilizing RGB LEDs for ambient lighting control. Besides pointing out practical challenges, preferred solutions for RGB LEDs are outlined and discussed to assist customers with engineering design solutions.

Edge-lit seven segment display


Debra over at Geek Mom Projects posted detailed instructions of how to build this edge-lit seven segment clocks:

This build combines small dozens of small laser-cut acrylic pieces which fit together with very tight tolerances. It uses skinny (4mm wide) LED strips which must be soldered, bent, and then slotted in between those acrylic pieces. When assembling the parts you must be willing to force pieces into place, even though it feels like you are stressing the brittle acrylic. You must also be willing to remove and re-seat said pieces and LED strips when it turns out they *can’t* actually be forced into place. At some point during the assembly there is a strong likelihood that you will have to remove everything and re-solder your LED strip when you realize that forcing everything into place broke one of the wires away from your LED strip or created a short circuit.

See the full post on Geek Mom Projects blog.

Check out the video after the break.

PocketPi MK2

img_20190518_140600 A smaller thinner PocketPi from Facelesstech:

Thinner with a simpler design but packing the same feature as before. At its heart is a raspberry pi zero W with a 3.5″ screen 480×320. It has all the GPIO pins available what aren’t being used by the screen. Its powered by a 2500mAh battery and has one full sized usb port. Its controlled by a bluetooth keyboard with trackpad

More details on Facelesstech blog.

Check out the video after the break.

App note: Eye safety for proximity sensing using infrared light-emitting diodes


A guide to human eye safety for designers of consumer products, app note from Renesas. Link here (PDF)

Active Proximity Sensing for Consumer products requires the use of a light-emitting component to illuminate the target object to be detected at some distance from the sensor. Typically, product designers do not want the illumination to interfere with the other functions of the product, or to distract the user during normal use. Therefore, Infrared Light-emitting Diodes (IR-LEDs) are used as the light-emitting components for proximity sensing. To further reduce the user awareness of the proximity function, the IR-LED and the proximity sensor are located under heavily tinted – but, infrared-transmitting – glass. While remaining unaware of any illuminating light source, the consumer indeed is exposed to low-levels of infrared radiation. All consumer products that emit light radiation – whether visible, ultraviolet, or infrared – must adhere to international standards that specify exposure limits for human eye safety.

App note: Basics on decoupling


See AVX technical note on how capacitors filter out transients in high speed digital circuits. Link here (PDF)

This paper discusses the characteristics of multilayer ceramic capacitors in decoupling applications and compares their performance with other types of decoupling capacitors. A special high-frequency test circuit is described and the results obtained using various types of capacitors are shown.

App note: Hand soldering tutorial for fine pitch QFP devices


No SMD tools removal and soldering of QFP packages tutorial from Silicon labs. Link here (PDF)

This document is intended to help designers create their initial prototype systems using Silicon Lab’s TQFP and LQFP devices where surface mount assembly equipment is not readily available. This application note assumes that the reader has at least basic hand soldering skills for through-hole soldering. The example presented will be the removal, cleanup and replacement of a TQFP with 48 leads and 0.5 mm lead pitch.

Building a Raspberry Pi UPS and serial login console with tinyK22 (NXP K22FN512)


Erich Styger has been working on a UPS with the Raspberry Pi to cover a short power out:

There are different ways to ruin a Linux system. For the Raspberry Pi which uses a micro SD card as the storage device by default, it comes with two challenges:
1.Excessive writes to the SD card can wear it out
2.Sudden power failure during a SD card write can corrupt the file system
For problem one I do I have a mitigation strategy (see “Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway“). Problem two can occur by user error (“you shall not turn it off without a sudo poweroff!”) or with the event of a power outage or black out. So for that problem I wanted to build a UPS for the Raspberry Pi.

Project info on MCU on Eclipse site.