The ConnectCore MP15 contains an STM STPMIC1A Power Management IC (PMIC). The PMIC is connected to the CPU via the I2C4 port (address 0x33).
The PMIC has the following features:
-
Four buck regulators
-
One boost regulator
-
Six low-dropout (LDO) regulators
-
DDR reference voltage
Kernel configuration
You can manage the driver support through the following kernel configuration option:
-
ST Microelectronics STPMIC1 PMIC driver (
CONFIG_MFD_STPMIC1
)
This option is enabled as built-in on the default ConnectCore MP15 kernel configuration file.
Kernel driver
The driver for STPMIC1 driver is located at:
File | Description |
---|---|
STPMIC1 driver |
Device tree bindings and customization
The STPMIC1 device tree binding is documented at Documentation/devicetree/bindings/mfd/st,stpmic1.yaml
.
The PMIC and its regulators are defined on the ConnectCore MP15 device tree at arch/arm/boot/dts/ccmp15.dtsi
.
Some regulators are used internally inside the ConnectCore MP15 and some are used externally on the carrier board. The settings of the external regulators can be modified in the carrier board device tree if required by your platform.
ConnectCore MP15 internal regulators
The following regulators are used internally on the ConnectCore MP15 and their parameters should not be modified. |
Device tree alias | STPMIC1 regulator | Description |
---|---|---|
|
buck1 |
Internal CPU power supply |
|
buck2 |
Internal DDR power supply |
|
buck3 |
SOM and DVK power supply |
|
ldo1 |
Internal ADC reference voltage |
|
ldo4 |
VDD_3V3_USBHS voltage supply |
|
vref_ddr |
DDR_REF voltage supply |
ConnectCore MP15 external regulators
The following regulators are routed outside the ConnectCore MP15 and may be used in the carrier board:
Device tree alias | STPMIC1 regulator | Type | Default voltage | Usage on ConnectCore MP15 Development Kit |
---|---|---|---|---|
|
buck4 |
Buck regulator |
3.3 V |
RS232, RS485, Ethernet PHY, USB hub, LVDS, parallel camera, Audio |
|
ldo2 |
LDO regulator |
0 V |
not used |
|
ldo5 |
LDO regulator |
3.3 V |
not used |
|
ldo6 |
LDO regulator |
1.8 V |
LVDS |
|
pwr_sw1 |
SW1 regulator |
5 V |
USB OTG |
|
pwr_sw2 |
SW2 regulator |
5 V |
not used |
Digi recommends you use the device tree alias for modifying the ConnectCore MP15 external regulator parameters in the final platform DTS file. |
Example of a regulator consumer in the device tree
Certain device drivers have a property in the form propname-supply
to help users define them as consumers of a power regulator.
You can use this property to provide the phandle of the regulator that powers the device.
This mechanism reduces the overall power consumption of the system by allowing the driver to enable the regulator when the interface is being used and disable it (or set a lower voltage) when the system goes to suspend or the driver is unloaded.
For example, on the ConnectCore MP15 Development Kit, the Micro SD connector is powered by PMIC buck4.
The sdmmc property vmmc-supply
allows you to define a power supply that will be controlled by the MMC driver.
&sdmmc2 {
pinctrl-names = "default", "opendrain", "sleep";
pinctrl-0 = <&sdmmc2_b4_pins_a>;
pinctrl-1 = <&sdmmc2_b4_od_pins_a>;
pinctrl-2 = <&sdmmc2_b4_sleep_pins_a>;
broken-cd;
disable-wp;
st,neg-edge;
bus-width = <4>;
vmmc-supply = <&v3v3>;
status = "okay";
};