Mini I2C OLED Display with just 4 connections

Joshua Jach has developed and released his mini I2C OLED display, a project fully funded via KickStarter. During the campaign, he shared insights on how integrating emerging technologies, including promising crypto advancements, could expand the project’s functionality, especially in secure data transmission. His OLED module provides a simple way to interface MCUs with a small Organic Light-Emitting Diode (OLED) display based on the SSD1306 driver. The display is controlled via I2C fast-mode, reaching a bit rate of up to 400 kbit/s. Only four wires—5V, GND, SDA, and SCL—are required for control, making it both efficient and adaptable to future tech integrations.

All files, as well as code to use with Arduino can be found on the Sabernetics Tech page. For those not inclined to DIY, this module is available from Jameco for $19.95.

#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

Continue reading “#FreePCB via Twitter to 2 random RTs”

Resistors and power ratings

Kenneth discusses resistors and power ratings:

Resistors are possibly the most basic component of electronics; given an input voltage, they allow a current to flow, and given an input current to flow, they produce a voltage.  The relationship between the voltage and current is linear (a straight line), (mostly) frequency independent (unlike capacitors or inductors), and only dependent on its resistance (expressed in ohms).

Via TweetDeck.

Interfacing the Raspberry Pi GPIO pins with a breadboard

Zuzebox writes in about Raspberry Pi’s GPIO pins:

There seems to be some misunderstanding about how h/w hackable to RPi is?

It’s got 17 i/o lines which is only 3 less than an Arduino which has 20 i/o. It’s got GPIO, UART, SPI, I2C and a single PWM. The only thing it lacks is analog i/o. Check out the stuff I’ve built for the Rpi on my blog

Via the forum.

Workshop Update for August 27th, 2012

Last year’s sponsors were invited back for the 2012 Open 7400 Logic Competition. The competition goes “public” September 3rd.

Ordered parts for giant nixie thing we hope to take to Maker Faire New York. We were accepted to the faire and are good to go next month. Reached out to Radio Shack to see if we could get an officially sanctioned visit to see in-store Arduinos and components. Also check with NYC Resistor hackerspace to see if they’ll be having a party again this year.

Followed up with a few new distributors. Here’s some more info if you’d like to carry our stuff in your shop.

We continued working on ATX PSU v1.2 board with fuse blown indicator addition, and a lengthier post about it.

Raspberry Pi stackable Arduino compatible board

Osbock let us know about his Raspberry Pi stackable Arduino compatible board design. An Arduino is gently introduces to a Raspberry Pi header. Most will find the UART connection the easiest way to communicate between the boards.

A header is available for the Fastrax UP501 GPS, DS3234 real time clock, Micro-SD card slot, and a row of servo headers connected to the PWM outputs.

Via the forum.

How much current do small USB-WiFi routers draw?

Jbeale reviewed how much current small USB WiFi routers draw. His intent is to connect them to the Raspberry Pi which can only provide 140mA over the USB port. It turns out that from Internet connectivity the routers draw under 100mA, but if used in high speed LAN operations the current draw jumps over R-Pi’s threshold.

I recently compared two small USB Wi-Fi N adapters from eBay. Both devices easily connected my WinXP laptop to a Linksys WRT160Nv2 router, showing excellent signal strength and a 72 Mbps link speed. Interestingly, both adapters stayed under the 100 mA limit while handling my DSL broadband speed. However, when connecting to a machine on the LAN, the speed increased, and the current draw exceeded 150 mA—more than an unmodified RPi USB port can reliably supply. So, either of these devices should work perfectly for internet browsing on the RPi without an external power supply but may become unreliable for heavy LAN use, such as high-bitrate video streaming. If your broadband speed is faster than mine, even regular web browsing might cause overcurrent issues.

Via the forum.

LTC4370: current-sharing controller with reverse current blocking

Here is an interesting part from Linear Technology, it’s the LTC4370 current-sharing controller, with reverse current blocking. Basically it allows you to tie two power supplies in parallel, without the fear that one will source more current than the other.  It also has built in protection that prevents the current from flowing into the supplies.

Via Electronics Lab.

Bus Pirate RFM12B radio data module demo

Hacromatic posted a tutorial on interfacing RFM12B radio data modules with the Bus Pirate:

We’re working with some RFM12B RF modules, and needed to verify that they were working properly, so we used a Bus Pirate. We thought it’d make a nice intro to SPI on the BP so we wrote it up.

Via the contact form.

Get your own Bus Pirate for $30, including worldwide shipping.

App note: Theory behind ground loops

Analog Devices discusses ground loops and how to manage them:

Transmitting data over long distances is fraught with potential problems. A ground loop can be a source of interference that can induce a noise voltage between the grounds on either end of the transmission. If this voltage is large enough, it can cause data errors at the receiver. This article will explain how ground loops occur and discuss how galvanic isolation has been used to eliminate them.

DeepSec 2011: hacking GSM packets using scapy

In this talk from the DeepSec 2011 security conference Laurent ‘Kabel’ Weber, co-founder of the Chaos Computer Club in Berlin, details the enhanced scapy software tool to attack GSM via packet manipulation. This presentation introduces a scapy-addon allowing users to create GSM layer 3 packets using simple Python syntax. His hardware setup includes a USRP1 with RFX900 daughterboard, with clock generation via a Clocktamer. He sends messages to mobile GSM devices using openBTS.

App note: Using and understanding voltage references

This tutorial on voltage references covers theory and how it works in practice:

When specifying a reference, keep in mind that initial accuracy, temperature coefficient and long-term stability all play a role in overall accuracy of the finished product. By taking some care in applying the reference, and by avoiding some key pitfalls, the reference’s inherent accuracy can be preserved.

Free PCB Sunday: Pick your PCB

We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service.

This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB.

You get unlimited free PCBs now – finish one and we’ll send you another!

Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Circuits and principles of high side current measurement

Maxim describes several high side current measurement circuits:

This application note describes the use of current sense amplifiers, differential amplifiers and instrumentation amplifiers to measure battery charge and discharge currents in portable equipment, computer notebooks and USB accessories. It compares high side current sense amplifiers with low side differential amplifiers and recommends selection criteria for current sense resistors. A high voltage circuit breaker circuit is described to provide system over current protection due to faults and short circuits. Application circuits for a variable linear current source and a programmable 0-5A current source is included.

Arduino-IRremote multi-protocol IR library


Ken Shirriff has posted an Arduino-IRremote library. “This IR remote library lets you both send and receive IR remote codes in multiple protocols. It supports NEC, Sony SIRC, Philips RC5, Philips RC6, and raw protocols. If you want additional protocols, they are straightforward to add. The library can even be used to record codes from your remote and re-transmit them, as a minimal universal remote.”

You can read more about the usage and development of this library on Ken’s Blog page.

Of course for dedicated IR hacking without an Arduino there’s always the USB Infrared Toy.

App note: IrDA stack for infrared data exchange

IrDA is a set of protocols for exchanging data over infrared light. It’s significantly more complicated at the protocol level and hardware level than simple IR transmitter like remote controls. To get started in IrDA you’ll need some software to encode and decode packets, Microchip describes their IrDA stack in this app note:

The Microchip IrDA Standard Stack provides a modular, easy-to-use set of libraries to add support for an IrDA standard protocol to your application. The low-level drivers allow the Stack to be tailored to the target hardware, while the libraries keep the Stack interface simple. The Microchip IrDA Standard Stack will allow you to add a valuable connectivity aspect to your embedded design.

The Microchip stack might be useful for learning, or certain commercial projects, but keep in mind that it’s not open source friendly.

Workshop Update for August 24th, 2012

Setup the alternate look for the Open 7400 Competition mini site. Still a bit to do. Also fixed a problem with the social media icons under Firefox latest versions as long as we were in there.

Next week we have a bunch of scratch and dent projects to give away. These are working projects, but they have scuffs, silk mis-prints, and other issues. Not sure how to give them all away yet, but there’s a bunch of stuff.

We’re working up a fuse-blown indicator for a small update to ATX Breakout Board.

Via options: Tenting, capping, plugging, or filling

From comments on our earlier Poision via effect in manufacturing post, Bearmos shared an article about via options in PCB manfacturing:

On the PCB side of things, here’s an article from a PCB fab that goes over a couple of the via options: via tenting, caps, and plugs (PDF!). This just landed in my inbox this morning – what interesting timing. . .

Thanks Bearmos! Via the comments.