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machine.PMIC – Functions to control the power management IC

The machine.PMIC class contains all of the functions to configure the S1 voltage rails, and configure the battery charger. Import it with

from machine import PMIC

To see what’s contained inside the class you can use the help() command

help(PMIC)

Functions

PMIC.charge_config(v, i)

  • Configures the battery charger. If no arguments are given, the current setting is printed as a tuple

  • If voltage, and/or current arguments are provided, the values will be set accordingly

  • Voltage v can be set between 3.6V and 4.3V (in 50mV steps)

  • Current i can be set between 7.5mA and 300mA (in 7.5mA steps). Note Value should be written as a float in mA, not A

      PMIC.charge_config(v=4.21, i=100)

  PMIC.charge_config() # Read the set parameters
  # Note the difference due to the resolution that can be set
  (4.2, 97.5)

PMIC.battery_level(enable)

  • Displays the current battery voltage as a float

  • Before reading the value, the voltage monitoring must be enabled

      PMIC.battery_level(True) # Enable monitoring
  PMIC.battery_level() # Read the battery level
  3.46

  PMIC.battery_level(False) # The monitoring can be disabled to save a small amount of power if not needed

PMIC.fpga_power(enable)

  • Enables or disables the FPGA core power rail

  • Setting this to False will automatically disable the Vio rail to avoid damaging the FPGA. Vio will need to be reconfigured manually after reenabling the FPGA core power rail

      PMIC.fpga_power() # Read the current state of the rail
  True

  PMIC.fpga_power(False) # Shuts down the FPGA core power rail

  PMIC.vio_config() # Read the Vio rail value
  # Will be set to 0V whenever the FPGA is shut down
  0

  PMIC.fpga_power(True) # Power on the FPGA again
  PMIC.vio_config(1.8) # You'll need to set the Vio rail again

PMIC.vaux_config(voltage)

  • Configures the buck-boost convertor of the Vaux rail

  • If no arguments are given, the current setting will be printed as a float

  • Can be set to 0V which turns off the rail, or between 0.8V and 5.5V

      PMIC.vaux_config(3.3) # Set the Vaux rail to 3.3V

  # Read the current setting
  PMIC.vaux_config()
  3.3

  • If Vio is set to be in load switch mode, the Vaux rail will be limited to 3.45V

PMIC.vio_config(voltage, lsw=False)

  • Configures the FPGA IO rail voltage, either in LDO mode, or load switch mode

  • If no arguments are given, the current setting will be printed

    • If Vio is configured as an LDO, the voltage setting will be returned as a float

    • If Vio is configured as a load switch, the state will be returned as a string. Either LOAD_SWITCH_ON or LOAD_SWITCH_OFF

  • Can be set to 0V which turns off the rail, regardless of the mode

      PMIC.vio_config(0) # Shuts down the rail

  • Can be set between 0.8V or 3.45V in LDO mode

      PMIC.vio_config(3.3, lsw=False) # Set Vio to regulate 3.3V in LDO mode

  PMIC.vio_config(3.3) # The same as above. lsw=False by default

  • Vio can also be configured as a load switch. In this mode the Vaux voltage is passed through directly to Vio. In this case, Vaux must not exceed 3.45V

      PMIC.vio_config(True, lsw=True) # Turn on the load switch (pass Vaux to Vio)
    
  PMIC.vio_config(False, lsw=True) # Turn off the load switch