Commit Graph

6 Commits

Author SHA1 Message Date
robert-hh 786013d467 docs/samd: Make use of pin names more consistent in examples.
This keeps up with the changed Pin naming scheme.
2023-05-04 13:19:19 +10:00
robert-hh dc8f9d22ca docs: Update the PWM examples based on recent API improvements.
This adds the freq and duty_u16 keyword settings to the constructor, and
sometimes other details in the PWM section.

For mimxrt a clarification regarding the PWM invert argument was added, and
for rp2 a few words were spent on PWM output pairs of a channel/slice.
2023-05-04 13:15:55 +10:00
robert-hh 250757716a samd/machine_pwm: Add init() method to PWM and simplify the PWM code.
The PWM.init() method has been added.  Calling init() without arguments
restarts a PWM channel stopped with deinit().  Otherwise single parameters
except for "device=n" can be changed again.  The device can only be
specified once, either in the constructor or the first init() call.

Also simplify get_pwm_config() and get_adc_config(), and shrink the PWM
object.
2023-05-04 13:10:38 +10:00
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 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