These include ADC, DAC, I2C, SoftI2C, SPI, SoftI2C, PWM, UART, pulse. This
is useful for devices like the Adafruit Trinket series which have almost no
accessible GPIO pins.
Signed-off-by: robert-hh <robert@hammelrath.com>
Even if boards do not have a clock crystal. In that case, the clock
quality will be very poor.
Always having machine.RTC means that the date/time can be set in a way that
is consistent with other ports.
This commit also removes the special code in modutime.c for devices without
the RTC class.
Signed-off-by: Damien George <damien@micropython.org>
Methods implemented are:
- rtc.init(date)
- rtc.datetime([new_date])
- rtc.calibration(value)
The presence of this class can be controlled by MICROPY_PY_MACHINE_RTC. If
the RTC module is used, the time module uses the RTC as well.
For boards without a 32kHz crystal, using RTC makes no sense, since it will
then use the ULP32K oscillator, which is not precise at all. Therefore, it
will by default only be enabled for boards using a crystal, but can be
enabled in the respective mpconfigboard.h.
It suuports 1 channel @ 10 bit for SAMD21, 2 channels @ 12 bit for SAMD51.
Instantiation by:
dac = machine.DAC(ch) # 0 or 1
Method write:
dac.write(value)
The output voltage range is 0..Vdd.
All board pins that have UART's assigned can be used. Baud rate range is
75 Baud to ~2 MBaud.
No flow control yet, and only RX is buffered. TX buffer and flow control
may be added later for SAMD51 with its larger RAM and Flash.
Features are:
- 3 to 5 different frequency groups.
- Freq range of 1Hz - 24 MHz.
- Duty rate stays stable on freq change.
Keyword options to the PWM constructor:
- device=n Select a specific PWM device. If no device is specified, a free
device is chosen, if available at that pin.
- freq=nnnn
- duty_u16=nnnn
- duty_ns=nnnn
- invert=True/False Allowing two outputs on the same device/channel to have
complementary signals.
If both freq and duty are provided, PWM output will start immediately.
Pins at the same device have the same frequency. If the PWM output number
exceeds the number of channels at the PWM device, the effctive channel_no
is output_no % channel_count. So with a channel count of 4, output 7 is
assigned to channel 3. Pins at a certain channel have the same frequency
and duty rate, but may be seperately inverted.
With the method read_u16(). Keyword arguments of the constructor are:
- bits=n The resolution; default is 12.
- average=n The average of samples, which are taken and cumulated. The
default value is 16. Averaging by hw is faster than averaging
in code.
The ADC runs at a clock freq 1.5 MHz. A single 12 bit conversion takes
8 microseconds.
