The early work on the PCB design uncovered a few issues with the initial goal. In particular, the SSRAM puts too much pressure on the PCB and routing so it is not possible to make a cheap 2-layers circuit. The free version of Eagle reaches the limits so it is not a viable solution, at least for the entry level. So I have decided to make 2 versions :
* The SSRAM-based board will be kept as a higher-performance option, with a slightly more expensive 4-layer PCB and the design is not available as Eagle files. Let's call it "version S"
* "Version A" uses Asynchronous SRAM, with a less demanding pinout. There are less power pins and less pressure on the routing, which should help keep the promises of Eagle design files and cheaper PCB. Memory capacity could be smaller too, there is more choice of parts. ASRAM is also somewhat slower but consumes less than SSRAM.
Both versions would be available in 3 ways : built and tested, or as a kit (build and test it yourself from the supplied parts), and if you feel adventurous, get the files and make everything yourself.
Before it's too late (like, too many contents) and because the default Dotclear blog system (from Gandi, the DNS+host provider) was too limited for our needs, Laura installed Drupal.
The contents have been updated moved over this new (more flexible) blog engine. Now we can resume our normal activities ! Thank you Laura :-)
Update : we still have to setup a decent download/upload system for easy updating...
Update 2010-12-23 : this old post is superseded by the discussion on the wiki about layout. The first routing attempt, as shown in the picture, used incorrect dimensions.
Trying to fit and route 3 power supply voltages on a 2-layer PCB is quite delicate, but if on top of that there are two fine-pitched QFP packages on each side, it's almost impossible. Well it seems that there is a (difficult) way but it requires a lot of vias... And I have not yet routed the data and address signals !
Other more recent SSRAM references need yet another supply voltage and this can't seriously fit with this system or organisation. At least 4 Layers become necessary, which drives the cost up. Fortunately the K7B401825B requires only 3.3V which is the main supply voltage.
Here is more insight into the board's design.
Update 2010-12-28 : look at the wiki for a clickable version of the image hereunder :
Concerning the inputs-outputs, let's have a look at http://arduino.cc/en/Main/Hardware : the "Arduino" shield pinout and functions are very basic and stable, though there exists a wide variety of additional features.
The Actuino boards will have the standard "shield" interface AND provide all the possible pins from the FPGA to additional connectors. The size and organisation will probably be similar to the MEGA 2560 : http://arduino.cc/en/Main/ArduinoBoardMega2560
Like this latest generation MEGA 2560, the Actuino uses an Atmel chip for the USB connexion. However we don't use the Atmega8U2 but the more powerful 32U2 (more SRAM and 4x more code space). It is directly derived from the Noogroove built by NooElec.
The ATmega2560 has 256KB of flash, Actuino has 2x more by default and that can be used for data or code as desired.
The only issues are :
* The Actel part is a 3.3V device and Arduino is typically 5V-compatible. Voltage translators will be probably added.
I'm sure you have questions, so here are some preliminary answers.
So... what is this Actuino thing ?
- It's an Arduino-compatible board
- it's based on Actel's A3P250 Flash FPGA
- It has much more RAM, Flash and MHz
- Because it's a FPGA, it is much more flexible. Do you want 20 16-bits PWM channels ? Piece of cake, nothing to worry about. Try this (as easily) with a microcontroller.
And... Why do it ?
- Arduino is... "limited".
- Because it is possible : we're in the 21th century, damnit !
- Because we can : we have the motivation, incentives and means
- Because its useful and fun
And... How is it done ?
- The PCB design uses skills, experience and tools from electronics professionals. A lot of technology is already available and ready for use !
- The FPGA contains a "soft core", its logic gate fabric emulates the Atmel processor of the Arduino (at first)
- A big Flash and SSRAM (each holding 512KB and capable of about 100MHz frequencies) provide a lot of storage for demanding projects
Oh cool, but it's going to cost a lot :-/
- Well, not that much more than a good, classic Arduino board.
- We are cost-conscious and want to keep the prices as low as reasonably possible.
This blog is used as a main page for the actuino website. It will contain the latest news, events, updates about this new and exciting project !
A wiki is opening as well, containing more technical, less social or volatile informations than on this blog.
For now, the "team" comprises (in no particular order) :
Things will rapidly evolve during the next days, stay tuned !