pyb — functions related to the pyboard

The pyb module contains specific functions related to the pyboard.

Time related functions

pyb.delay(ms)

Delay for the given number of milliseconds.

pyb.udelay(us)

Delay for the given number of microseconds.

pyb.millis()

Returns the number of milliseconds since the board was last reset.

The result is always a micropython smallint (31-bit signed number), so after 2^30 milliseconds (about 12.4 days) this will start to return negative numbers.

pyb.micros()

Returns the number of microseconds since the board was last reset.

The result is always a micropython smallint (31-bit signed number), so after 2^30 microseconds (about 17.8 minutes) this will start to return negative numbers.

pyb.elapsed_millis(start)

Returns the number of milliseconds which have elapsed since start.

This function takes care of counter wrap, and always returns a positive number. This means it can be used to measure periods upto about 12.4 days.

Example:

start = pyb.millis()
while pyb.elapsed_millis(start) < 1000:
    # Perform some operation

pyb.elapsed_micros(start)

Returns the number of microseconds which have elapsed since start.

This function takes care of counter wrap, and always returns a positive number. This means it can be used to measure periods upto about 17.8 minutes.

Example:

start = pyb.micros()
while pyb.elapsed_micros(start) < 1000:
    # Perform some operation
    pass

Reset related functions

pyb.hard_reset()

Resets the pyboard in a manner similar to pushing the external RESET button.

pyb.bootloader()

Activate the bootloader without BOOT* pins.

Interrupt related functions

pyb.disable_irq()

Disable interrupt requests. Returns the previous IRQ state: False/True for disabled/enabled IRQs respectively. This return value can be passed to enable_irq to restore the IRQ to its original state.

pyb.enable_irq(state=True)

Enable interrupt requests. If state is True (the default value) then IRQs are enabled. If state is False then IRQs are disabled. The most common use of this function is to pass it the value returned by disable_irq to exit a critical section.

Power related functions

pyb.freq([sysclk[, hclk[, pclk1[, pclk2]]]])

If given no arguments, returns a tuple of clock frequencies: (sysclk, hclk, pclk1, pclk2). These correspond to:

• sysclk: frequency of the CPU
• hclk: frequency of the AHB bus, core memory and DMA
• pclk1: frequency of the APB1 bus
• pclk2: frequency of the APB2 bus

If given any arguments then the function sets the frequency of the CPU, and the busses if additional arguments are given. Frequencies are given in Hz. Eg freq(120000000) sets sysclk (the CPU frequency) to 120MHz. Note that not all values are supported and the largest supported frequency not greater than the given value will be selected.

Supported sysclk frequencies are (in MHz): 8, 16, 24, 30, 32, 36, 40, 42, 48, 54, 56, 60, 64, 72, 84, 96, 108, 120, 144, 168.

The maximum frequency of hclk is 168MHz, of pclk1 is 42MHz, and of pclk2 is 84MHz. Be sure not to set frequencies above these values.

The hclk, pclk1 and pclk2 frequencies are derived from the sysclk frequency using a prescaler (divider). Supported prescalers for hclk are: 1, 2, 4, 8, 16, 64, 128, 256, 512. Supported prescalers for pclk1 and pclk2 are: 1, 2, 4, 8. A prescaler will be chosen to best match the requested frequency.

A sysclk frequency of 8MHz uses the HSE (external crystal) directly and 16MHz uses the HSI (internal oscillator) directly. The higher frequencies use the HSE to drive the PLL (phase locked loop), and then use the output of the PLL.

Note that if you change the frequency while the USB is enabled then the USB may become unreliable. It is best to change the frequency in boot.py, before the USB peripheral is started. Also note that sysclk frequencies below 36MHz do not allow the USB to function correctly.

pyb.wfi()

Wait for an interrupt. This executies a wfi instruction which reduces power consumption of the MCU until an interrupt occurs, at which point execution continues.

pyb.standby()

pyb.stop()

Miscellaneous functions

pyb.have_cdc()

Return True if USB is connected as a serial device, False otherwise.

pyb.hid((buttons, x, y, z))

Takes a 4-tuple (or list) and sends it to the USB host (the PC) to signal a HID mouse-motion event.

pyb.info([dump_alloc_table])

Print out lots of information about the board.

pyb.mount(device, mountpoint, *, readonly=False, mkfs=False)

Mount a block device and make it available as part of the filesystem. device must be an object that provides the block protocol:

• readblocks(self, blocknum, buf)
• writeblocks(self, blocknum, buf) (optional)
• count(self)
• sync(self) (optional)

readblocks and writeblocks should copy data between buf and the block device, starting from block number blocknum on the device. buf will be a bytearray with length a multiple of 512. If writeblocks is not defined then the device is mounted read-only. The return value of these two functions is ignored.

count should return the number of blocks available on the device. sync, if implemented, should sync the data on the device.

The parameter mountpoint is the location in the root of the filesystem to mount the device. It must begin with a forward-slash.

If readonly is True, then the device is mounted read-only, otherwise it is mounted read-write.

If mkfs is True, then a new filesystem is created if one does not already exist.

To unmount a device, pass None as the device and the mount location as mountpoint.

pyb.repl_uart(uart)

Get or set the UART object that the REPL is repeated on.

pyb.rng()

Return a 30-bit hardware generated random number.

pyb.sync()

Sync all file systems.

pyb.unique_id()

Returns a string of 12 bytes (96 bits), which is the unique ID for the MCU.

Classes

• class Accel – accelerometer control
• class ADC – analog to digital conversion: read analog values on a pin
• class CAN – controller area network communication bus
• class DAC – digital to analog conversion
• class ExtInt – configure I/O pins to interrupt on external events
• class I2C – a two-wire serial protocol
• class LCD – LCD control for the LCD touch-sensor pyskin
• class LED – LED object
• class Pin – control I/O pins
• class PinAF – Pin Alternate Functions
• class RTC – real time clock
• class Servo – 3-wire hobby servo driver
• class SPI – a master-driven serial protocol
• class Switch – switch object
• class Timer – control internal timers
• class TimerChannel — setup a channel for a timer
• class UART – duplex serial communication bus
• class USB_VCP – USB virtual comm port