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4 Commity (7ad41bc2d80fc757cbd73295ba233db4c56b8d48)

Autor SHA1 Wiadomość Data
robert-hh 76cf98c35b samd/mcu: Implement a hardware seed for the SAMD21 random module. 
By using the phase jitter between the DFLL48M clock and the FDPLL96M clock.
Even if both use the same reference source, they have a different jitter.
SysTick is driven by FDPLL96M, the us counter by DFLL48M.  As a random
source, the us counter is read out on every SysTick and the value is used
to accumulate a simple multiply, add and xor register.  According to tests
it creates about 30 bit random bit-flips per second.  That mechanism will
pass quite a few RNG tests, has a suitable frequency distribution and
serves better than just the time after boot to seed the PRNG.
 2023-02-21 23:15:29 +11:00
robert-hh e69313f89c samd: Add a vref=num option to the ADC and DAC constructor. 
ADC: The argument of vref=num is an integer. Values for num are:

    SAMD21:
    0  INT1V   1.0V voltage reference
    1  INTVCC0 1/1.48 Analog voltage supply
    2  INTVCC1 1/2 Analog voltage supply (only for VDDANA > 2.0V)
    3  VREFA   External reference
    4  VREFB   External reference

    SAMD51:
    0  INTREF  internal bandgap reference
    1  INTVCC1 Analog voltage supply
    2  INTVCC0 1/2 Analog voltage supply (only for VDDANA > 2.0v)
    3  AREFA   External reference A
    4  AREFB   External reference B
    5  AREFC   External reference C (ADC1 only)

DAC: The argument of vref=num is an integer. Suitable values:

    SAMD21:
    0  INT1V   Internal voltage reference
    1  VDDANA  Analog voltage supply
    2  VREFA   External reference

    SAMD51:
    0  INTREF Internal bandgap reference
    1  VDDANA Analog voltage supply
    2  VREFAU Unbuffered external voltage reference (not buffered in DAC)
    4  VREFAB Buffered external voltage reference (buffered in DAC).
 2022-12-14 12:48:24 +11:00
robert-hh b3ce059767 docs/samd/pinout: Fix the pin numbering for the default assignments. 
It still used the 'old' pin numbers.
 2022-11-08 23:24:35 +11:00
robert-hh 11910e2fa1 docs/samd: Add documentation for the samd port. 
Includes a general overview, a quickref, pinout tables, and the beginnings
of a tutorial.
 2022-10-26 23:39:35 +11:00