Tutorial - Bricklets with EEPROM vs Co-Processor

Early 2017 we started to replace all of the existing Bricklets with new versions. These new versions have a co-processor instead of an EEPROM and they have a different connector.

To re-design and replace about 50 Bricklets is of course a mammoth task. So why did we do it?

Old Bricklet with EEPROM

The old Bricklets with EEPROM had parts like sensors, analog-digital converters, LEDs, interface extensions etc. These parts were directly connected to the processor on the Bricks (through a Bricklet cable). This concept has the advantage, that simple Bricklets only need few parts. Every Bricklet had an EEPROM that saved the code for the Brick. This code was loaded by the Brick, written into its own flash and executed periodically. Because of this a Brick did not have to know each individual Bricklet. This allowed for a big variety of different building blocks.

A disadvantage was, that the processor of the Brick had to run all of the Bricklet code as well as the code for the Brick functionality itself. Applications like a frequency counter or similar, that need to react permanently to a signal, were not possible to realize. Another disadvantage was that the code of the Bricklets was only compatible to the SAM3 and SAM4 processors from Atmel. After Microchip bought Atmel it was not clear anymore how long these processors will be available.

Because of these problems we decided to replace all of these Bricklets with new ones that have a co-processor.

New Bricklet with Co-Processor

The new Bricklets have their own co-processors that only have two tasks:

  • To implement the Bricklet functionality and
  • to communicate with a Brick.

Compared to the old Bricklets with EEPROM, the new Bricklets with co-processor now have a fixed protocol that can be implemented by any processor. So the Bricks do not need to use a specific kind of processor anymore.

Additionally, we can now have Bricklets that

While the old Bricklets with EEPROM could only be connected to a Brick, the new Bricklets can in theory be read out by any device that can speak SPI.

This allowed us to develop the Isolator Bricklet as well as the Bricklet HAT (comming soon) and Bricklet HAT Zero (comming soon).

There are many other small technical advantages that increase the performance and robustness of the new Bricklets compared to the old ones.

And last but not least, we were able to replace the old 10 pole connector with a new more robust and user-friendly 7 pole connector. A detailed explanation about the connector change can be found here.

It took us about 2.5 years and many many engineering man-hours to design the new Bricklets and replace all of the old ones. Nevertheless, in hindsight we are very happy with the result and we are certain that the efforts were worthwhile.