Where did all the Flash go?

Firmware
4

Hi @bko

That's an interesting comment - so I did some research ...

There are three factors that affect how much flash is available for the user application.
Total Flash on the platform, bootloader size, and base firmware size.

Amount of flash on platform (from Arduino IDE boards.txt & Spark docs)

 32K    Arduino UNO, Pro, Mini   (Atmega328)
256K    Arduino Mega 2560        (Atmega2560)
 32K    Arduino Pro Micro        (Atmel32U4)
128K    Spark                    (ST32M)
128K    RFduino                  (nRF51822)

Size of the bootloader (from Arduino IDE boards.txt & Spark docs)

  0      Arduino UNO
 2K      Arduino Pro Mini
 4K      Arduino Mega 2560
 4K      Arduio Pro Micro
20K      Spark
  0      RFduino

Size of an empty setup() and loop() application (rough estimate of base firmware)

466 bytes  Arduino UNO, PRO, Mini, Micro
466 bytes  Arduino Mega 2560
73K bytes  Spark
466 bytes  RFduino

Flash available for user application (available flash - bootloader - base firmware)

31.5K      Arduino UNO
29.5K      Arduino Pro Mini
251.5K     Arduino Mega 2560
27.5K      Adruino Pro Micro
35K        Spark
127.5K     RFduino

So the Spark has slightly more flash available to the user application than several of the Arduino platforms, but significantly less than Arduino Mega and RFduino.

Spark has a lot of potential (SRAM and Processing speed) however with so much code overhead in the support of the cloud it falls into the smaller category of platforms by reducing the flash available for the user application.

SRAM for comparison

 2K        Arduino UNO, PRO Mini
 2.5K      Arduino Pro M
 8K        Arduino MEGA
 20K       Spark
 8K        RFduino

Spark takes the lead with available SRAM, which is probably why it can support a TCP/IP stack. :smile:

I should point out that because of the base firmware on the Spark the user application could consume less firmware because of leveraging any library function already included in the base firmware - in otherwords the user application may take up less space in flash on the Spark vs other platforms due to the presence of library routines already loaded in support of the Spark protocol.

I am hopeful that the hardware abstraction re-factor going may provide an opportunity to reduce the base firmware size. :smile:

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