The problem with the Atmel 8-bit AVR's on most Arduinos, is that eventually you want the extra Flash memory and RAM that an ARM can bring, with the increased clock speed also being welcome.

The problem being that the Arduino Due, CHIPKIT 32, Rasp. Pi etc, are 3.3v boards, making them incompatible with many Arduino Shields.

5 Volt ARM's do exist:
http://www.edn-europe.com/5varmcorte...85+Europe.html

So if anyone has, or does come across a 5V ARM-based Arduino compatible or similar, post it here

Yeah I noticed that too, Deckie. Might be easier to work a voltage divider into your circuit somewhere, when interfacing the raspi and arduino. Going to a 'non-standard' version of the MC might lead to other problems.

Pete

Don't forget you can easily add an i2c bus EEPROM or FRAM chip for much larger memory using only 2 analog pins for more storage. I did this with my MonsterShield. You can add 8 of these chips off the same 2 pins.

That's what makes I2C so attractive. Have you experienced any latency at all?

It all depends on what you want to do. I had no trouble reading 64 bytes of animation data (what I called a block) at a time every few seconds for my MonsterShield during live record & playback. Actually I *thought* I had an issue and ended up trying a FRAM chip to solve it. While the FRAM chip is WAY faster than EEPROM (and was a drop-in replacement for the EEPROM chip), it turns out that I didn't need it. I had a bug in my code that was causing a time shift after each load of the next block of animation data. EEPROM is obviously going to be way slower than RAM. I don't remember the exact timings, but I flashed an LED every time I was reading or writing a block of data. The flash of the LED was a fraction of a second with EEPROM.... maybe 50ms long? With the FRAM it was probably 5-10ms for the same 64 bytes of data? I'm just guessing... I didn't actually measure it. You could barely see the LED flash with the FRAM.

Originally Posted by Skystream

Don't forget you can easily add an i2c bus EEPROM or FRAM chip for much larger memory using only 2 analog pins for more storage. I did this with my MonsterShield. You can add 8 of these chips off the same 2 pins.

Interesting, and if I find or build an I2c version, it can be addressed by other Arduinos as well

Ferroelectric RAM (FeRAM, F-RAM or FRAM) is non-volatile random-access memory technology that will not lose its mind or data when the power is turned off. Similar to flash memory.

EEPROM (also written E2PROM and pronounced "e-e-prom," "double-e prom," "e-squared," or simply "e-prom") stands for Electrically Erasable Programmable Read-Only Memory and is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration tables or device configuration. (Wikipedia)

PROM (Permanent Read Only Memory), allows users to program its contents exactly once by physically altering its structure with the application of high-voltage pulses, setting of each bit is like blowing by a microscopic fuse ('burning' memory).

ROM (Read Only Memory)