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# Voltage reference 1.2 V

You can configure pad MCA_IO2 to output a steady temperature-compensated 1.2 V output to use as a voltage reference for external peripherals.

CAUTION! For this functionality to work properly you must connect a 100 nF capacitor between MCA_IO2 and ground to filter ripple signals in the output. Connect the capacitor as close as possible to the module pad.

## Kernel configuration

The 1.2 V voltage reference functionality is part of the MCA core driver and does not require any special kernel option.

## Platform driver mapping

The MCA core driver is located at:

File | Description
--- | ---
drivers/mfd/mca-cc6ul-core.c | ConnectCore 6UL MCA core driver

## Device tree bindings and customization

The voltage reference functionality does not require any device tree property.

## Using the voltage reference output

The functionality is controlled by a sysfs entry. To enable the voltage reference on MCA_IO2 pad:

    ~# echo enabled > /sys/bus/i2c/drivers/mca_cc6ul/0-007e/vref

To disable it:

    ~# echo disabled > /sys/bus/i2c/drivers/mca_cc6ul/0-007e/vref

To read the current status of the pad:

    ~# cat /sys/bus/i2c/drivers/mca_cc6ul/0-007e/vref
    disabled

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Voltage reference 1.2 V updated on 22 January 2018 02:43:37 PM