pycom – Pycom Device Features

The pycom module contains functions to control specific features of the Pycom devices, such as the heartbeat RGB LED.

Quick Usage Example

import pycom

pycom.heartbeat(False)  # disable the heartbeat LED
pycom.heartbeat(True)   # enable the heartbeat LED
pycom.heartbeat()       # get the heartbeat state
pycom.rgbled(0xff00)    # make the LED light up in green color

Functions

pycom.heartbeat([enable])

Get or set the state (enabled or disabled) of the heartbeat LED. Accepts and returns boolean values (True or False).

pycom.heartbeat_on_boot([enable])

Allows you permanently disable or enable the heartbeat LED. Once this setting is set, it will persist between reboots. Note, this only comes into effect on the next boot, it does not stop the already running heartbeat.

pycom.rgbled(color)

Set the colour of the RGB LED. The colour is specified as 24 bit value representing red, green and blue, where the red colour is represented by the 8 most significant bits. For instance, passing the value 0x00FF00 will light up the LED in a very bright green.

pycom.nvs_set(key, value)

Set the value of the specified key in the NVRAM memory area of the external flash. Data stored here is preserved across resets and power cycles. Value can only take 32-bit integers at the moment. Example:

import pycom

pycom.nvs_set('temp', 25)
pycom.nvs_set('count', 10)

pycom.nvs_get(key)

Get the value the specified key from the NVRAM memory area of the external flash. Example:

import pycom

pulses = pycom.nvs_get('count')

If a non-existing key is given the returned value will be None.

pycom.nvs_erase(key)

Erase the given key from the NVRAM memory area.

pycom.nvs_erase_all()

Erase the entire NVRAM memory area.

pycom.wifi_on_boot([enable])

Get or set the WiFi on boot flag. When this flag is set to True, the AP with the default SSID (lopy-wlan-xxx for example) will be enabled as part of the boot process. If the flag is set to False, the module will boot with WiFi disabled until it's enabled by the script via the WLAN class. This setting is stored in non-volatile memory which preserves it across resets and power cycles. Example:

import pycom

pycom.wifi_on_boot(True)   # enable WiFi on boot

pycom.wifi_on_boot()       # get the wifi on boot flag

pycom.wdt_on_boot([enable])

Enables the WDT at boot time with the timeout in ms set by the function wdt_on_boot_timeout. If this flag is set, the application needs to reconfigure the WDT with a new timeout and feed it regularly to avoid a reset.

import pycom

pycom.wdt_on_boot(True)     # enable WDT on boot

pycom.wdt_on_boot()         # get the WDT on boot flag

pycom.wdt_on_boot_timeout([timeout])

Sets or gets the WDT on boot timeout in milliseconds. The minimum value is 5000 ms.

import pycom

pycom.wdt_on_boot_timeout(10000)     # set the timeout to 5000ms

pycom.wdt_on_boot_timeout()         # get the WDT timeout value

pycom.pulses_get(pin, timeout)

Return a list of pulses at pin. The methods scans for transitions at pin and returns a list of tuples, each telling the pin value and the duration in microseconds of that value. pin is a pin object, which must have set to INP or OPEN_DRAIN mode. The scan stops if not transitions occurs within timeout milliseconds.

Example:

# get the raw data from a DHT11/DHT22/AM2302 sensor
from machine import Pin
from pycom import pulses_get
from time import sleep_ms

pin = Pin("G7", mode=Pin.OPEN_DRAIN)
pin(0)
sleep_ms(20)
pin(1)
data = pulses_get(pin, 100)

pycom.ota_start()

pycom.ota_write(buffer)

pycom.ota_finish()

Perform a firmware update. These methods are internally used by a firmware update though FTP. The update starts with a call to ota_start(), followed by a series of calls to ota_write(buffer), and is terminated with ota_finish(). After reset, the new image gets active. buffer shall hold the image data to be written, in arbitrary sizes. A block size of 4096 is recommended.

Example:

# Firmware update by reading the image from the SD card
#
from pycom import ota_start, ota_write, ota_finish
from os import mount
from machine import SD

BLOCKSIZE = const(4096)
APPIMG = "/sd/appimg.bin"

sd = SD()
mount(sd, '/sd')

with open(APPIMG, "rb") as f:
    buffer = bytearray(BLOCKSIZE)
    mv = memoryview(buffer)
    size=0
    ota_start()
    while True:
        chunk = f.readinto(buffer)
        if chunk > 0:
            ota_write(mv[:chunk])
            size += chunk
            print("\r%7d " % size, end="")
        else:
            break
    ota_finish()

Instead of reading the data to be written from a file, it can obviously also be received from a server using any suitable protocol, without the need to store it in the devices file system.