Tag Archives: USB

Protecting the USB from over voltage and overcurrent threats


An application note from Littelfuse about USB protection.

This application note addresses the various requirements for protecting the Universal Serial Bus (USB) from overcurrent and overvoltage environmental threats. The solutions presented cover both USB 1.1 and the higher speed USB 2.0 circuitry. Specific emphasis is placed on USB 2.0 with information directed at hot connection over current conditions and electrostatic discharge (ESD) induced in the USB system.

Protecting the USB from over voltage and overcurrent threats – [Link]

A development board for the STM32F042


Andy Brown designed a development board for the STM32F042 in the TSSOP20 package:

This project came about because I’m using the STM32F042F6P6 (32Kb flash, 6Kb SRAM) in another project where I’m creating a USB device and the first thing I did is try to obtain a development board for it. I was hopeful that ST would have created one of their ‘discovery’ boards but no, there was only a ‘nucleo’ board available and that had one of the QFP packages on it.

A development board for the STM32F042 – [Link]

Choosing $1 sound card for DC-capable low speed oscilloscope


Tomasz Ostrowski has tested some cheap USB sound cards as low speed oscilloscope interfaces/recorders. He writes:

I’ve tested some cheap ($1) USB sound cards for DC sampling capability, in particular for using as low speed oscilloscope/signal recorder. Some (http://tomeko.net/dsoundscope/c_media.php or one from this thread: http://www.elektroda.pl/rtvforum/topic3106124.html) don’t seem to work despite removing DC blocking capacitor, but this one: http://tomeko.net/dsoundscope/C_Media2/ is fine. With just 120k resistor connected it is able to measure voltage from 0-6V range (cons: its input is at 2V level, sourcing 8uA if connected to GND and it’s single channel only). For test purposes I’ve prepared DLL interface for miniscope v4 (Win32 oscilloscope GUI) calibrated for this particular setup (example traces available).

Choosing $1 sound card for DC-capable low speed oscilloscope – [Link]

USB PIC Programmer

DSCF2014-1024x768Stefano Purchiaroni rebuild a USB PIC Programmer that he found online. He writes:

This page is dedicated to everybody needs to program a PIC (Microchip) device via USB port. Looking on the web for ready-to-use projects, I found a good one called Open Programmer, coming with several schematics, PCBs and Open Source code. The original link is http://openprog.altervista.org/OP_ita.html

What concerned me was the need to mount, on the mainboard, a specific socket board depending on the model of PIC being programmed. Moreover, the proposed layout did not meet my personal “compact look” ideas. So, I propose hereafter a small layout version of that circuit, adopting a single smart on-board ZIF socket. This version sacrifices many non-PIC microcontroller models. I will thank everybody proposing a larger range implementation, suitable to program Atmel and other devices. Anyway, if your goal is to program PIC devices, you are on the good site.

A small box, a USB connector, a ZIF socket, two leds. That’all in my compact proposal.

USB PIC Programmer -[Link]

PIC24 bedside table alarm clock


Markus Gritsch posted pictures and code of his PIC24 bedside table alarm clock:

Another year, another clock, but for the first time for my alarm clocks. I am not using an MSP430 but a PIC24 instead. Standby current is with 5.5 µA only slightly higher than that of my MSP430 based ones. Time keeping is done using the RTCC pheripheral, which I also used for the first time.
It can be seen in action in this YouTube video
Friendly green digits :)
And of course it has a LiFePO4 battery on its back, being charged every few years using my new USB charger.
A photo transistor is also included to dim the display in the dark. Much nices to the eyes when checking what time it is in the middle of the night.

PIC24 bedside table alarm clock – [Link]

LiFePO4 charger


Markus Gritsch shared his LiFePO4 charger project in the forum:

Since I really like using LiFePO4 AA and AAA batteries in some of my projects, I finally gave in and built a dedicated charger for them.
Previously I used a lab power supply to mimic the constant current/constant voltage charging curve, which worked also fine. But after seeing Patrick Van Oosterwijck nifty LiFePO4wered/USB™, I thought it would be a bit more convenient to charge these batteries using USB.

LiFePO4 charger – [Link]

Open source pocket USB oscilloscope; 30 MHz, multi-platform


by Graham Prophet @ edn-europe.com:

Running on Apple iPad, Android, Microsoft Windows and Linux, LabNation’s (Antwerp, Belgium) open source USB oscilloscope, SmartScope, is the result of a Kickstarter campaign commenced in 2014 – the project raised 645% of the funding goal within 30 days.

Believed to be the first test equipment designed to run on multiple operating systems and platforms such as smartphones, tablets and PCs, the lightweight SmartScope is powered directly from the host’s USB interface suiting it for many test and measurement applications far from the workbench.

Open source pocket USB oscilloscope; 30 MHz, multi-platform – [Link]

Miniscope v2f


Here is another variant (after miniscope v2a, b, c, d, e) of simple PC/USB oscilloscope/recorder:


It extends miniscope v2e with PGA (MCP6S21) offering same sampling frequency (480 ksps, 8 bit real time streaming to PC allowing continuous recording up to 512M samples) but 8 gain ranges and high input impedance. Estimated price is $6 – $7 if using homemade PCB (single sided, 1.35 sq inches).

Miniscope v2f – [Link]

USB power supply active load tester


Sasa Karanovic has designed and built a DIY USB power Supply active load tester, that is available at GitHub:

USB Power supply Active Load Tester or short PAL Tester is unit designed for testing the quality of the power supplies.
Idea was to create low-cost, precise device for simultaneous measurement of Voltage and Current drawn from the device under test.

USB power supply active load tester – [Link]