Friday, March 19, 2010

The InterSceptre

This blog will also be used to inform you about the Sceptre, the open source & hardware ARM7-based 32-bit fast prototyping platform as published in Elektor. In the Pages box on the right of this article you will find a link to a special Sceptre page. All information about updates will be posted there; it is sort of the project’s home page.

The Sceptre is my baby and (for the moment) I do all the development for it. Currently I am working on an extension I/O board on which you can plug a Sceptre so that it can talk to the rest of the world. At the same time my goal is to make this board as universal as possible so that it can also be used with other microcontrollers. Except for its name, InterSceptre, and some component print this I/O board will not be Sceptre specific.

The InterSceptre is due for the June issue of Elektor and I am almost done with the circuit diagram. The board will feature lots of communication interfaces: 2x RS-232, 2x RS-485 (so RS-422 is possible too), MIDI in/out, DMX-512 (OK, that’s just RS-485 with a different connector), a WIZnet module for Internet connection, SPI, PS/2 and I2C. USB is available on the Sceptre itself, but a dedicated USB connector for ISP/serial comms will be on the InterSceptre. I also added a JTAG connector and a 4-way multiplexed DAC (the LPC2148 used on the Sceptre has a 10-bit DAC). To stay flexible the board will have a 25-pin DB connector to give access to the ADC inputs and PWM outputs, and some other GPIO.

All of this can of course (unfortunately) not be used at the same time, but I am confident that it will be useful anyway for many applications.

The universal side of the board is also emphasized by its power supply and it will work with 5V and 3V3 systems. The Sceptre is a 3V3 system but 5V tolerant and I will soon show you how you can use it with a 5V I2C controller.

Contrary to the Sceptre, the InterSceptre will only use easy to solder (change/replace/remove) through-hole parts so mounting it will be possible for anyone capable of holding a soldering iron.

That’s all for now folks, I have a PCB to draw.

Thursday, March 11, 2010

It's a tactile green embedded world

Last week I visited Embedded World 2010 in Nuremberg in Germany. Nuremberg is a nice city with a mediaeval city center and even though I had a hotel room right on the main market place, I did not see much of the town because of the show. The show was pretty big, more than 700 exhibitors spread out over three halls and allthough I spent two full days there, I did not have enough time to see everything.

The main theme of the show was green electronics. Lots of companies showed off green products, low-power boards and microcontrollers. Although low power electronics is very important, there were not many real green novelties. Microamps per megahertz is the most common term now and several manufacturers claim that their products have the lowest number. Unfortunately these numbers are difficult to compare, because one manufacturer talks about a 32-bit controller whereas another is talking about an 8-bit controller. Actually uA/Mhz is not a good measure, it would be better to use something like uA/MIPS or so. Energy Micro, a company that I didn't know before, won the Embedded World award in the category Hardware. Their EFM32 32-bit MCU (ARM Cortex-M3) consumes 180 uA/MHz (running at 32 MHz and 3V).

Another big thing these days is touch technology. In the coming years everything will be tactile, if we can believe the Embedded World exhibitors. Personally I am a bit weary of touch interfaces. At the end of the seventies touch keys were hot too. Being a poor student I had recovered a third-hand color TV with touch keys for the channel selection. These keys were very sensible to weather conditions and my TV changed station randomly, especially when humidity was high or when I really wanted to see something. One day this TV caught spontaneously fire and I finally got rid of it, but that's another story.

Now I have a monitor with touch keys. I also have a cat. It has happened several times that the cat changed the settings of my monitor in a completely random way just by striking the tactile surface of the monitor. I guess I’ll just have to wait until the touch craze has passed before I buy any new kit.