OpenMV MicroPython libraries

Warning

Important summary of this section

  • MicroPython provides built-in modules that mirror the functionality of the Python standard library (e.g. os, time), as well as MicroPython-specific modules (e.g. bluetooth, machine).

  • Most Python standard library modules implement a subset of the functionality of the equivalent Python module, and in a few cases provide some MicroPython-specific extensions (e.g. array, os)

  • Due to resource constraints or other limitations, some ports or firmware versions may not include all the functionality documented here.

  • To allow for extensibility, some built-in modules can be extended from Python code loaded onto the device filesystem.

This chapter describes modules (function and class libraries) which are built into MicroPython. This documentation in general aspires to describe all modules and functions/classes which are implemented in the MicroPython project. However, MicroPython is highly configurable, and each port to a particular board/embedded system may include only a subset of the available MicroPython libraries.

With that in mind, please be warned that some functions/classes in a module (or even the entire module) described in this documentation may be unavailable in a particular build of MicroPython on a particular system. The best place to find general information of the availability/non-availability of a particular feature is the “General Information” section which contains information pertaining to a specific MicroPython port.

On some ports you are able to discover the available, built-in libraries that can be imported by entering the following at the REPL:

help('modules')

Beyond the built-in libraries described in this documentation, many more modules from the Python standard library, as well as further MicroPython extensions to it, can be found in micropython-lib.

Python standard libraries and micro-libraries

The following standard Python libraries have been “micro-ified” to fit in with the philosophy of MicroPython. They provide the core functionality of that module and are intended to be a drop-in replacement for the standard Python library.

OpenMV Cam libraries

The following sections describe the libraries available on each OpenMV-supported board, including both the MicroPython-specific built-ins and OpenMV’s own extensions.

Common modules

Built into the firmware on every OpenMV camera board.

Frozen Python helpers shipped on most OpenMV camera boards (drivers, networking, and utilities):

Networking helpers (require a working network interface):

Port-specific modules

Modules tied to a specific MCU family. See the per-board sections below for which boards include each one.

Hardware drivers

Drivers for sensors, displays and other peripherals shipped on one or more OpenMV-supported boards. See the per-board sections below for which boards include each one.

Per-board availability

The lists below show which port-specific and driver modules are shipped on each board. All the modules in Common, Frozen Python helpers, and Networking helpers (above) are available on every camera board unless otherwise noted.

OPENMV_N6 (STM32N6)

OpenMV N6 (STM32N6 — STMicroelectronics’ first NPU-equipped MCU):

  • pyb — functions related to the board

  • stm — functionality specific to STM32 MCUs

  • ssd1306 — OLED driver

  • tb6612 — TB6612 motor driver

OPENMV_AE3 (Alif Ensemble E3)

OpenMV AE3 (Alif Ensemble E3 MCU):

  • alif — Alif Ensemble SoC functions

  • lsm6dsox — LSM6DSOX 6-axis IMU

  • romfs — ROMFS helper utilities

  • pca9674a — PCA9674A I2C expander driver

OPENMV_RT1060 (i.MX RT1060)

OpenMV RT1060:

  • mimxrt — functionality specific to NXP i.MXRT

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • onewire — 1-Wire bus protocol

  • ds18x20 — DS18x20 temperature sensor driver

  • neopixel — control of WS2812 / NeoPixel LEDs

  • ssd1306 — OLED driver

  • tb6612 — TB6612 motor driver

  • pca9674a — PCA9674A I2C expander driver

OPENMVPT (Pure Thermal, STM32H7 + DVI/HDMI)

OpenMV Pure Thermal:

  • pyb — functions related to the board

  • stm — functionality specific to STM32 MCUs

  • tfp410 — DVI/HDMI serializer

  • ft5x06 — capacitive touchscreen driver

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • onewire — 1-Wire bus protocol

  • ds18x20 — DS18x20 temperature sensor driver

  • neopixel — control of WS2812 / NeoPixel LEDs

  • ssd1306 — OLED driver

  • tb6612 — TB6612 motor driver

OPENMV2 / OPENMV3 / OPENMV4 / OPENMV4P (STM32)

Legacy STM32-based OpenMV camera boards:

  • pyb — functions related to the board

  • stm — functionality specific to STM32 MCUs

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • onewire — 1-Wire bus protocol

  • ds18x20 — DS18x20 temperature sensor driver

  • neopixel — control of WS2812 / NeoPixel LEDs

  • ssd1306 — OLED driver

  • tb6612 — TB6612 motor driver

ARDUINO_GIGA (STM32H7 + touchscreen)

Arduino Giga R1 WiFi:

  • pyb — functions related to the board

  • stm — functionality specific to STM32 MCUs

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • onewire — 1-Wire bus protocol

  • neopixel — control of WS2812 / NeoPixel LEDs

  • gt911 — GT911 5-point capacitive touch controller

  • ft5x06 — capacitive touchscreen driver

ARDUINO_PORTENTA_H7 (STM32H7)

Arduino Portenta H7:

  • pyb — functions related to the board

  • stm — functionality specific to STM32 MCUs

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • ds18x20 — DS18x20 temperature sensor driver

  • onewire — 1-Wire bus protocol

  • neopixel — control of WS2812 / NeoPixel LEDs

  • lora — LoRa modem driver

  • ssd1306 — OLED driver

  • tb6612 — TB6612 motor driver

ARDUINO_NICLA_VISION (STM32H7)

Arduino Nicla Vision:

  • pyb — functions related to the board

  • stm — functionality specific to STM32 MCUs

  • lsm6dsox — LSM6DSOX 6-axis IMU

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • ds18x20 — DS18x20 temperature sensor driver

  • onewire — 1-Wire bus protocol

  • neopixel — control of WS2812 / NeoPixel LEDs

ARDUINO_NANO_33_BLE_SENSE (Nordic nRF52840)

Arduino Nano 33 BLE Sense — board-specific imu wrapper that selects between the LSM9DS1 (Rev 1) and BMI270 + BMM150 (Rev 2) sensor sets, plus:

  • bmi270 — BMI270 6-axis IMU

  • bmm150 — BMM150 3-axis magnetometer

  • lsm9ds1 — LSM9DS1 9-axis IMU

  • hts221 — HTS221 humidity/temperature sensor

  • lps22h — LPS22HB/HH pressure sensor

  • hs3003 — HS3003 humidity/temperature sensor

  • apds9960 — proximity, gesture, and color sensor driver

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • onewire — 1-Wire bus protocol

  • ds18x20 — DS18x20 temperature sensor driver

  • neopixel — control of WS2812 / NeoPixel LEDs

ARDUINO_NANO_RP2040_CONNECT / RPI_PICO (RP2)

RP2040-based boards. The Arduino Nano RP2040 Connect adds a few extra companion-chip drivers; the Raspberry Pi Pico ships only with the core upstream drivers.

Arduino Nano RP2040 Connect:

  • espflash — ESP32 ROM bootloader firmware flasher

  • lsm6dsox — LSM6DSOX 6-axis IMU

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • onewire — 1-Wire bus protocol

  • ds18x20 — DS18x20 temperature sensor driver

  • neopixel — control of WS2812 / NeoPixel LEDs

Raspberry Pi Pico:

  • dht — DHT11 and DHT22 temperature/humidity sensors

  • onewire — 1-Wire bus protocol

  • ds18x20 — DS18x20 temperature sensor driver

  • neopixel — control of WS2812 / NeoPixel LEDs

Extending built-in libraries from Python

A subset of the built-in modules are able to be extended by Python code by providing a module of the same name in the filesystem. This extensibility applies to the following Python standard library modules which are built-in to the firmware: array, binascii, collections, errno, gzip, hashlib, heapq, io, json, os, platform, random, re, select, socket, ssl, struct, time zlib, as well as the MicroPython-specific machine module. All other built-in modules cannot be extended from the filesystem.

This allows the user to provide an extended implementation of a built-in library (perhaps to provide additional CPython compatibility or missing functionality). This is used extensively in micropython-lib, see Package management for more information. The filesystem module will typically do a wildcard import of the built-in module in order to inherit all the globals (classes, functions and variables) from the built-in.

In MicroPython v1.21.0 and higher, to prevent the filesystem module from importing itself, it can force an import of the built-in module it by temporarily clearing sys.path during the import. For example, to extend the time module from Python, a file named time.py on the filesystem would do the following:

_path = sys.path
sys.path = ()
try:
  from time import *
finally:
  sys.path = _path
  del _path

def extra_method():
  pass

The result is that time.py contains all the globals of the built-in time module, but adds extra_method.

In earlier versions of MicroPython, you can force an import of a built-in module by appending a u to the start of its name. For example, import utime instead of import time. For example, time.py on the filesystem could look like:

from utime import *

def extra_method():
  pass

This way is still supported, but the sys.path method described above is now preferred as the u-prefix will be removed from the names of built-in modules in a future version of MicroPython.

Other than when it specifically needs to force the use of the built-in module, code should always use import module rather than import umodule.