An application from Maxim: Introduction to SHA-256 Master/Slave authentication
A new group of secure authenticators and a companion secure coprocessor/1-Wire® master implement SHA-256 authentication. This application note explains the general logistics of this SHA-256-based security system and introduces the bidirectional authentication functionality that the authentication system uses.
Supertronic posted pictures of his new stencil printer design in the forum:
I did a new stencil printer design it will be avaliable before machine production starts.
It can print 300x200mm stencils and is used for prototyping.
Kevin Rye posted an update on his LCD clock project:
Now that I’ve spent some time working with SMD Atmegas, I decided to redo the PCB to make it all SMD. By moving the Atmega to the SMD version, I picked up some additional space on the PCB. That allowed me to add a 4th button to the PCB for the alarm function. In addition to the alarm button, there’s also a status LED for the alarm. The LED indicates that the alarm is set. I can even make it flash when the alarm is active. I could either use the Alarm button to enter the alarm menu to set the time, or add the alarm time to the main menu and use the alarm button as a snooze or a simple on/off toggle. Skies the limit!
Every Friday we giveaway some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:
Continue reading “Free PCB coupon via Facebook to 2 random commenters”
Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.
Coming up:
Sverre Holm writes:
Ultrasonic distance sensors can find the range out to 2-4 meters and are popular in e.g. robotics. Here I look at how the accuracy can be improved by compensating for the variation of speed of sound with temperature. It actually varies quite a lot in air and around 0 C it is:
c = 331.3 + 0.606 * T
where c is in m/s and T is in C. The formula is good to up to at least +/-30 C. There is also a dependence of humidity, but as it is so small it is neglected here.
Via the contact form.
Viswa wrote to us about the USB-to-UART CP2104-MINIEK (mini evaluation kit) from Silicon Labs available for $5.
Via the contact form.
The Bus Pirate v4 Acrylic case kit v1 is back in stock at Seeed Studio. This fits the earlier Bus Pirate v4 models which comes in the non-Sick of Beige PCBs.
You can get one for $3 at Seeed Studio.
Here’s Catmacey’s digital side of the Chipstomp. He wrote a post on his blog detailing its assembly:
I started with the digital side of things. The first task being to get the PIC and it’s supporting circuitry up and running and confirm that all was ok by attempting to talk to it with my PicKit 3.
After assembly and half an hour of head scratching I found my first mistake. Some how along the way I connected the ICSP clock line to pin 2 rather than pin 5 of the PIC. Luckily this wasn’t to hard to fix with a knife and a small bodge-wire.
Once that was done the Pickit 3 detected the PIC ok and I could program and (and verify) the Chipkit DP32 bootloader.
How often have you been caught without the right cables? You can salvage an old ugly one from somewhere, or make a last minute part order that delays your project. Never again! The Premium Make Your Own Keyed Cable Kit from Dangerous Prototypes contains enough housing and sockets to make an (almost) lifetime supply of cables.
Choose the connector, or combination of connectors, that best fit your project. Slide the pre-crimped rainbow ribbon cable into the connector until you hear a snap. Now you’re ready to go!
This cable cornucopia contains keyed connectors, meaning the cable can only be attached one way. Connect without fear of short circuits or reversed polarity!
2.54 mm (0.1″) Keyed Crimp Housings:
2, 3 Pin x30 pieces each
4, 5, 6, 8, 10 Pin x20 pieces each
12, 16, 20 Pin x10 pieces each
2.54 mm (0.1″) Keyed Crimp Connectors:
2, 3 Pin x30 pieces each
4, 5, 6, 8, 10 Pin x20 pieces each
12, 16, 20 Pin x10 pieces each
Pre-crimped Cables:
100 mm x2 with crimps
200 mm x2 with crimps
300 mm x2 with crimps
40 Wire, 16 gauge
10 Colors (brown, red, orange, yellow, green, blue, purple, grey, white, black)
Bonus gear:
A practical tray to organize the parts on a shelf
What is OOMP?
Premium Cable Kit is part of the Open Organization Method for Parts. A project to help your workshop have the right parts available, right now. What to know more? See our expanding universe at OOMP.
You can get the Keyed Cable Kit for $50 at Seeed.
Fabio Battaglia blogged about his Ithaca Audio Z80 CPU card for the S100 bus project:
First of all, I assembled some simple test code to write a letter on my video console, just to check that code was actually executing. Obviously I only got a black screen at first, which seems a constant when I build these cards. I ended up tracing the problem on pin 53 of the bus: on the IEEE696 standard (the last, and official, iteration of the bus) that pin is always grounded, on the Ithaca card the pin is used to enable/disable internal buffer to allow manual data input on the processor lines. Once found, it was a matter of disconnecting a two IC legs and a little rewiring.
Pull out pin 2 of IC14 and tie it to 5v, then pull out pin 12 of IC16. That’s it. And then, the board started to show signs of life!
Martin Kumm writes:
This page provides documents about a cheap SMD solder station built as an Arduino shield (Arduino UNO). It supports active soldering tips from Weller (RT series) which contain the heating element as well as a sensor and provides a standard 3.5 mm jack. Together with the corresponding female connector you will get a compact SMD soldering iron (see pictures below) with very fast heat up times of a few seconds.
The shield consists of a low-noise amplifier for measuring the temperature via the ADC of the AVR, a power MOSFET stage to control the heating using PWM and a 7-segment LED display and push buttons for setting and displaying the temperature. The controller is realized digitally on the AVR.
Hardware and software are open source.
Via the contact form. Thanks Devgiant!
Alan Parekh of Hacked Gadgets writes:
If you are doing any electrical work, one of these Non Contact Voltage Test Pens can be quite handy. Just touch the wire that you want to make sure isn’t live and check that the tester doesn’t beep and start flashing. This test pen is on all the time monitoring for AC between 90V and 1000 V. I would have preferred the device to have an on/off switch which would allow the battery to last even longer but I guess they figured that the 1.5 year life that they rate this for when in standby was good enough. This impressive life is because they got the current draw down to under 10 micro amps! Even when operating it only draws a handful of milli amps.
The board is quite thin at 0.8mm, this is half the typical generic PCB thickness which is 1.6mm. In large quantities the thinner board might be cheaper but typically anything thinner or thicker than 1.6mm is a premium price at most board houses that I know about.
The main component of the board is a 74HC14D hex inverting buffer the data sheet (PDF) shows a maximum supply current to the chip of 2 micro amps which makes sense based on our current readings. You can see a schematic below that Warren Young reverse engineered from a similar device (not the same but very similar operation).
Check out the video after the break. Continue reading “Non contact voltage test pen teardown”
Bus Blaster v3 JTAG debugger is back in stock at Seeed Studio.The cool thing about the Bus Blaster is that it uses a programmable logic chip as a buffer. It can imitate different types of programming hardware with a simple USB update. You can get a Bus Blaster v3 for $34.95.
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:
Some stuff:
We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.
TonyD posted pictures of his latest batch of PCB’s from DirtyPCBs:
In the box where 4, yes 4 sets of PCB’s.
In the photo, the big PCB at the back is RPi-X PIAC. On the photo front row, on the left is MiniPiio LED Breakout, in the centre is MiniPiio BOP4 and to the right is MiniPiio PWM16
From the comments on our earlier USB oscilloscope with signal generator post, here’s a PC storage oscilloscope and logic analyzer by Nerd Ralph:
A logic analyzer is a useful tool when working with micro-controllers, but when compared to the price of Arduino compatible boards, they are expensive. While the ability to decode different protocols is a nice convenience, the key functionality of a logic analyzer is the ability to record a signal over a period of time. For low-speed signals in the tens of kbps, a PC audio codec can perform this function.
The audio codecs in most modern PCs are capable of at least 96kbps stereo sampling at 16 bits per sample, with 192kbps/24-bit “HD audio” being relatively common. This is enough to analyze a 38.4kbps UART signal in modest detail (5 samples per bit). With some hardware to connect to the audio input and software to record and view the signal data it is possible to have the functionality of a basic storage oscilloscope and logic analyzer.
Via the comments.
A library for I2C communications for Linux devices – the Lsquaredc by Jan Rychter, that is available at Github:
Lsquaredc is a tiny Linux library that allows you to access I2C (IIC, I²C, or I squared C) from userspace without causing excessive pain and suffering. The library uses the Bus Pirate convention for specifying I2C sequences, supports repeated start, and has been tested on the BeagleBone Black and Raspberry PI.
Via the contact form.
Nerd Ralph writes:
I’ve blogged before about PL-2303HX USB-TTL adapters. In some ways they are even better than the expensive FTDI adapters – for example they work at 6mbps. In conjunction with a cheap Pro Mini clone it’s possible to get started with Arduino/AVR programming for $5. For more advanced use such as burning bootloaders or directly programming AVR chips, I usually recommend a USBasp. While writing picoboot-avrdude, I noticed avrdude supports bit-bang SPI programming not just with a parallel port, but also with a serial port. Here’s how hacked a PL-2303HX module so I could use it as a bit banging SPI AVR programmer.
Via the contact form.
Tom Keddie writes:
This week at VHS we’re building Logic Pirates in our SMD workshops. The LP is an awesome little open hardware logic analyser design from DP.
The ICSP header is a tiny 0.05″ pitch, I struggled with this a little until I came up with this top and bottom 0.1″ jig (obvious in hindsight).
The LP is currently OOS at Seeed, I’m selling the extra PCBs on Tindie
