RS232 Breakout Board for Raspberry-P

The Raspberry-Pi  will be with us soon. In the mean time I would like to share a little RS232 breakout PCB I”ve designed for use with the RPi.

It”s a simple RS232 circuit using a MAX3232 chip connected to the UART Rx and Tx of the RPi.

I”ve not included any mounting holes as I don”t know if the final RPi will have any, although I hope to add some for the next version. It was pointed out on the RPi forums that the RPi’s 3.3v supply is limited to 50mA so I may add a 3.3V regulator to the circuit. A MCP1703 from Microchip was recommended, The addition current from an additional  3.3V regulator will useful if you want to use the prototyping area on the breakout board. That said the RPi’s 3.3V at 50mA is enough for the MAX3232 by itself.

The design was done in DesignSpark PCB and I”ll post the design files and gerbers in due course and I expect to get some finished PCB”s after the Chinese New Year

Initial schematic for v0.10 is here

ARDvance-Pi v0.1

The ARDvance-Pi is an advance Arduino training board. You can use it together with any of the Ardunio Uno or Duemilanove style of boards. The Arduino is plugged into the ARDvance-Pi and DIL switches allow the user to select which interfaces or circuits they want to connect to the Ardunio.

The training board has a number of interfaces

• 6 x Rotary Potentiometers
• 2 x Linear Potentiometers
• 4-Digit, 7-segment LED display
• Temperature Sensor
• Light Sensor
• Buzzer Output
• 5V/3.3V switchable PSU
• Prototyping area
• 8 x LEDs
• 8 x tactile switches
• 1-ch Relay (Change Over)
• RS232 interface with 9-W D connector
• H-Bridge Motor Controller (based on L298)
• XBee socket
• 16-way keypad*
• LCD interface*
• 5V to 3.3V logic conversion for Raspberry-Pi

* Note: if space allows

It was originally going to be called the ARDvance-10 but its name changed when I decided to add an interface port for the Raspberry Pi board, hence its new name ARDvance-Pi. Port Expanders, either MCP23008 or PCF8573 and a 8-ch ADC will also be added to allow I2C or SPI interfaces to be used from the Raspberry-Pi. When its finished, its hoped that the Raspberry-Pi can use the Arduino as a sort of slave I/O processor.

The schematic is here: Ardvance Pi Schematic 0v10

MAX7456 OSD Shield (v0.1)

Here’s a beta release of a On Screen Display (OSD) shield I’ve been working on, it still needs a bit tiding up.

It uses a MAX7456 from Maxim for the video overlay function. The MAX7456 is connected to the Ardunio’s SPI port (MOSI, MISO and CLK) and a double row of 0.1 headers can be used to choose which digital pin drives chip select (CS) for the MAX7456.

In addition to the MAX7456 OSD chip, there’s also a DS1307 Real Time Clock (RTC) with battery backup for displaying time and date in the video feed.

I designed it using DesignSpark PCB, pulling in the MAX7456 footprint from the Sparkfun PCB library. I’ll post design files and gerbers shortly.

For software, I used code from Arduino forum members dfraser and zitron in this Arduino forum post.

osd – Arkwork.pdf
osd – Schematic.pdf

Arduino PLC Software

The Ardunio PLC design I designed is nothing without software to drive it.

My initially thoughts was to hardcod the process logic using C programming code. This would involve reading from the AVR’s I/O pins with digitalRead() and writing back using digitalWrite(). Process Logic in-between the “in” and “out” instructions would be written using if’s, else’s and switch C statements to perform the desired logic task. After spending some time in the Raspberry-Pi forums, I realised this approach while fine for myself and other C programmers but it would not be suitable for beginners.

So, I’ve begun looking at ways to make a full PLC programming environment for the Arduino PLC.

A developer will write their PLC statements using a PC based environment such as free automation tools from and Beremiz and CoDeSys. Once the plc program is complete, it can download the control program to a IEC-61131 run time such as LDmicro, executing on the Arduino PLC hardware.

Some useful sites:

http://www.plctutor.com
http://www.plcmanual.com
http://www.beremiz.org
http://www.cq.cx/ladder.pl
http://www.3s-software.com/

32-bit Arduino

At last the Arduino team have announced an official 32-bit ARM board.

The specs look pretty standard for a ARM Cortex-M3 but they’re nice specs none the less.

The uC is a SAM3U processor from Atmel with the following specs:

• Speed: 96MHz
• Program Memory: 256Kb Flash
• Data Memory: 52Kb SRAM
• Digital I/O: 5 SPI buses, 2 I2C interfaces, 5 UARTS
• Analog I/O: 16ch 12-bit Analog Inputs.

Not sure of the PCB package size but it looks like a 100 or 144 pin TQFP.

I’m not sure if the SAM3U uC is 5V tolerant, which could be a problem for some 5V only shields.

On the whole the 32-bit Arduino looks like a winner, now lets hope the 32-bit Arduino software is as good as the hardware.

Raspberry Pi – An ARM Linux box for $25

I’ve been a fan David Braben work since his (and Ian Bell’s) awesome Elite video game from the 80′s.

It was with great interested when I read about his latest hardware venture “Raspberry Pi” – An ARM Linux box for $25.

The specs for the Raspberry Pi are impressive

• credit-card-sized
• Broadcom BCM2835 application processor
• Ethernet interface using LAN9512 at the $35 price point
• 128MB of RAM at the $25 price point
• 256MB of RAM at the $35 price point

 

The first alpha PCB’s are back and they have successfully managed to get Linux working on them, with their latest blog entries showing the boards running a port of Quake 3.

With shipping quoted for the end of 2011, I know what I want for Christmas this year

 

Maker Space @ Newcastle

Last night (20th July 2011) saw the first drop in session for the Newcastle Maker Space.

A big thanks goes to Alistair and Brian for allowing us to use their office space at the Star and Shadow (and the tea and biscuits).

For those who couldn’t attend, we had about 10 or so makers turn up which is a good start considering it wasn’t advertised.

After a quick round of introductions, we got talking on what we would all like to get from a maker space. From the friendly discussions I think people want:

• * A friendly drop in club to chat with others, seek advice on those troubling tech problems, show and tells etc.
• * a workspace with space and access to equipment to work on their projects
• * workshops to learn or help others

While the maker space finds its feet so to speak, we’ve palnning on drop in sessions every 1st and 3rd Wednesday’s of the month. Check the Maker Space web site and discussion group for more details.

DesignSpark PCB to Google SketchUp in 3D

DesignSpark have released a small conversion program which will take a DesignSpark PCB’s 3D IDF output and convert it into a format Google SketchUp can import.

To make the most of this you need to enter height data for the components on your PCB. But this is pretty easy, you need open the property dialog for a component either on the schematic or layout and select “values” and edit the “component height” value. If you’re doing this on the schematic you’ll need to forward annotate the design changes to the PCB layout before outputting the PCB as a IDF model.

At the moment it just gives you a simple “skyscraper” 3D model, but even this is useful for checking for space clashes when you come to integrate your PCB design into a mechanical design.

“PCB Converter for SketchUp allows designers to import Intermediate Data Format (IDF) files into Google SketchUp. The new module adds a 3D CAD back-end capability to PCB design tools and takes SketchUp into the electronic product design domain.”

A tale of two boards

Lately I’ve been keeping my eye on two recent developments from Xmos and Parallax.

The Xmos staff are developing a Stamp (40-pin DIP package PCB) like board for their XS1-L1-TQFP48.

Mean while Parallax to support their Semiconductor spin off have brought a new Quick Start board of their popular Propeller P8X32A multicore microcontroller.

Maker Faire UK 2011

The Maker Faire UK was back at Newcastle on the weekend 12th and 13th March 2011.

This year Abs and Sid were actually looking forward to going to the Faire, no arguments or huffy pants, in the back of the car they jumped and off we went.

This years Maker Faire as definitely bigger and better than last years. More floor space, more stands and more visitors.

In the makerspace, Abs decided to build a Maker Faire UK 2011 LED Badge, a RGB light thingy and a Drawdio noise making pencil. While Sid built the same LED badge and RGB light thingy but chose to build a LED light cube instead of the Drawdio.

It was great to meet some old friends and makers:

Aaron from Oomlout was there with their Arduino boards.

Jim and Kat from Sonodrome with their 555 step sequencer and their newest project an AUV (looking forward to seeing it fly Jim )

Brian from Lab in a Box showing off his chemistry skills with his college showing off an early version of the OpenPCR.

Oli was there again with his interactive light table

John brought his UK101′s again and a new or should I say “old” Roland plotter churnning out coloured drawings.

and some new makers

Mark founder of Minty Geek was showing off their neat electronics kits.

Malcolm from Weird Motors with an array of homebuilt electric vehicles

Dave from BodgeitQuick with an impressive homebuilt RepRap

Martin showing off his mini ROV’s.

The legend poster that is Mike Cook (aka Grump Mike) from the Arduino forums showing off his Electric Harp and Hexome Arduino sequencer.

The world renouned hardware hacker Mitch Altman was there again working the maker area, helping the young and old to get making. The old guy from the Gadget Show was doing the rounds with a camera crew.