machine module contains specific functions related to the hardware
on a particular board. Most functions in this module allow to achieve direct
and unrestricted access to and control of hardware blocks on a system
(like CPU, timers, buses, etc.). Used incorrectly, this can lead to
malfunction, lockups, crashes of your board, and in extreme cases, hardware
A note of callbacks used by functions and class methods of
all these callbacks should be considered as executing in an interrupt context.
This is true for both physical devices with IDs >= 0 and “virtual” devices
with negative IDs like -1 (these “virtual” devices are still thin shims on
top of real hardware and real hardware interrupts). See Writing interrupt handlers.
Returns a byte string with a unique identifier of a board/SoC. It will vary from a board/SoC instance to another, if underlying hardware allows. Length varies by hardware (so use substring of a full value if you expect a short ID). In some MicroPython ports, ID corresponds to the network MAC address.
time_pulse_us(pin, pulse_level, timeout_us=1000000)¶
Time a pulse on the given
pin, and return the duration of the pulse in microseconds. The
pulse_levelargument should be 0 to time a low pulse or 1 to time a high pulse.
If the current input value of the pin is different to
pulse_level, the function first (*) waits until the pin input becomes equal to
pulse_level, then (**) times the duration that the pin is equal to
pulse_level. If the pin is already equal to
pulse_levelthen timing starts straight away.
The function will return -2 if there was timeout waiting for condition marked (*) above, and -1 if there was timeout during the main measurement, marked (**) above. The timeout is the same for both cases and given by
timeout_us(which is in microseconds).
- class Pin – control I/O pins
- class Signal – control and sense external I/O devices
- class UART – duplex serial communication bus
- class SPI – a Serial Peripheral Interface bus protocol (master side)
- class I2C – a two-wire serial protocol
- class RTC – real time clock
- class Timer – control hardware timers
- class WDT – watchdog timer