New Arduinos

The Arduino team announced some new Arduino’s:

The “Arduino Leonardo” is simpler, and should be significantly cheaper than an Arduino because it uses an ATmega with on-board USB. This looks pretty much like a “Teensy” from PJRC but with an Arduino UNO board layout.

The “Arduino Due” uses an ARM Cortex-M3 processor, in this case an Atmel SAM3U4. Unfortunately, that chip is quite big, 100-pin or 144 pin, so cost might be an issue. Atmel might give them good discounts,. We will see. It is forecast to be available by end of year.

From the brief spec, I think it is a 144-pin part, the SAM3U4E. That gives lots of Input and Output (I/O) pins. I am very interested in small robots, so that is quite big for a micromouse.

Compared to the ARM Cortex-M3 I am working with already, the ST Micro STM32F103, the exciting new feature of the Atmel SAM3U is high-speed USB (480Mbits) on-board, and it runs at 96MHz.

In other STM32F comparisons, I think the STM32F is slightly better for my areas of interest, though I would have to use a 144-pin STM32F part to get the full external memory interface.

The SAM3U does not have any Digital to Analogue Converters (DACs), whereas the comparable STM32F103xC (high density) part has two. Comparable STM32F has three 12-bit Analogue to Digital Converters (ADCs) which is slightly better than the SAM3U4 two ADCs. There is an interface to good quality audio chips called I2S. SAM3U4 has one I2S interface, while STM32F103 has two. What does this all mean? If you want to build audio projects, the STM32F might be a better starting point.

It is extremy useful for robots to keep track of their own position by measuring wheel movement (odometery). The technique often used is the same as older ‘ball’ mice. Internally a ball mouse has two orthogonal small wheels which rotate when the ball rotates. The two orthogonal wheels have slots. Light shines though the slots, and each time the light beam is broken, movement is detected. By using two beams and two sensors on each wheel, it can tell which direction the ball is moving. This technology is a quadrature encoder.

Quadrature decoders are very useful to track and time the quadrature encoder. STM32F103 timers can each implement a quadrature decoder, and hence some parts can provide upto 6. I had thought I’d misunderstood the SAM3U4 datasheet, but Atmel have confirmed it only has one quadrature decoder. This is not an issue, unless you want to build robots which ‘know’ where they are.

I am very pleased that the Arduino team are working on ARM Cortex-M3. I think this will encourage a lot more people to use the 32-bit ARM platform. Coretx-M3 is capable of so much more than the 8-bit ATmega, that I expect a significant flurry of new projects next year when the Arduino Due is fully developed.

Meanwhile, I’ll keep working on STM32F, and watch out for results from the Arduino Due .

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