Is the Zero/Samd21 really worth more ?

Hardware Arduino Zero
1

As I was thinking of getting into this chip, I said, well, its an ARM Cortex processor, and I will be able to almost do anything possible right?

As I dive into it more and more, I can see that many things are really exactly like any previous Atmel chip, and it has almost the same limitations as the others.

So what ARM Cortex 48Mhz 32bits even means where :

  1. the DAC is so slowly that you can barely output a sine wave larger then a few Khz
  2. the ADC has 12 bits, where in this resolution it becomes so slowly to 2us !! you cant sample any signal above few Khz
    3.The high resolution timer(24 bits) really means almost nothing when you deal with 1Mhz timer, because 48Mhz clock is not that fast.

There are more and more, but as I came to realise , this chip means not really more then any old 16bits Atmel such as 328p.

I couldn't find too many reasons to say - this is a "real" processor, because when you dig into any of its specifications, you see it means nothing with a 48Mhz clock.

2

The SAMD21G18A on the Arduino Zero costs about the same as the Atmega 32U4 used on the Mirco/Leonardo, both have native USB, but the SAMD21G:

runs between 2-3 times faster,
has 8 times more flash memory,
more than 12 times more RAM,
contains 6 timers (4 x 16-bit, 2 x 24-bit) as opposed to 4 timers (8-bit, 10-bit & 2 x 16-bit)
6 configurable Serial/SPI/I2C ports instead of 1 Serial, 1 SPI and 1 I2C ,
highly configurable peripheral pins rather than fixed,

...these are just some of its advantages.

I feel the main disadvantage with the SAMD21 is that it feels a though your writing code for an ARM core with bolted on peripherals, rather than the complete and seamless architecture offered by the AVR. However, in terms of performance there's no contest.

3

True, unless you deal high frequencies (both in and out).
Its an ARM that can barely output or read frequencies above 3Mhz for many reasons (Nyquist sampling rate for the ADC and DAC)