This is the v1.22.0 version of the MicroPython documentation. The latest development version of this page may be more current.

machine — functions related to the hardware

The 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 damage.

A note of callbacks used by functions and class methods of machine module: 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.

Memory access

The module exposes three objects used for raw memory access.


Read/write 8 bits of memory.


Read/write 16 bits of memory.


Read/write 32 bits of memory.

Use subscript notation [...] to index these objects with the address of interest. Note that the address is the byte address, regardless of the size of memory being accessed.

Example use (registers are specific to an stm32 microcontroller):

import machine
from micropython import const

GPIOA = const(0x48000000)
GPIO_BSRR = const(0x18)
GPIO_IDR = const(0x10)

# set PA2 high
machine.mem32[GPIOA + GPIO_BSRR] = 1 << 2

# read PA3
value = (machine.mem32[GPIOA + GPIO_IDR] >> 3) & 1

Miscellaneous functions


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.

machine.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_level argument 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_level then 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).

machine.bitstream(pin, encoding, timing, data, /)

Transmits data by bit-banging the specified pin. The encoding argument specifies how the bits are encoded, and timing is an encoding-specific timing specification.

The supported encodings are:

  • 0 for “high low” pulse duration modulation. This will transmit 0 and 1 bits as timed pulses, starting with the most significant bit. The timing must be a four-tuple of nanoseconds in the format (high_time_0, low_time_0, high_time_1, low_time_1). For example, (400, 850, 800, 450) is the timing specification for WS2812 RGB LEDs at 800kHz.

The accuracy of the timing varies between ports. On Cortex M0 at 48MHz, it is at best +/- 120ns, however on faster MCUs (ESP8266, ESP32, STM32, Pyboard), it will be closer to +/-30ns.


For controlling WS2812 / NeoPixel strips, see the neopixel module for a higher-level API.


Return a 24-bit software generated random number.

Availability: WiPy.



IRQ wake values.


Reset causes.


Wake-up reasons.