Writes the value of VOUT_COMMAND to set the output voltage of a PMBus regulator rail. Communicates with the device directly using the I2C interface.
This action should be executed during configuration for the rail.
The PMBus specification defines four modes/formats for the value of VOUT_COMMAND:
Currently only the linear format is supported. The decimal value of the "volts" property is converted into linear format before being written.
The linear data format requires an exponent value.
If the device supports the PMBus VOUT_MODE command, the exponent value can be read from the device.
If VOUT_MODE is not supported by the device, the exponent value must be specified using the "exponent" property. The exponent value can normally be found in the device documentation (data sheet).
If you wish to verify that the specified volts value was successfully written to VOUT_COMMAND, specify the "is_verified" property with a value of true.
The value of VOUT_COMMAND will be read from the device after it is written to ensure that it contains the expected value. If VOUT_COMMAND contains an unexpected value, an error will be logged and no further configuration will be performed for this regulator rail.
To perform verification, the device must return all 16 bits of voltage data that were written to VOUT_COMMAND. The PMBus specification permits a device to have less than 16 bit internal data resolution, resulting in some low order bits being zero when read back. However, verification is not supported on devices that provide less than 16 bit internal data resolution.
| Name | Required | Type | Description |
|---|---|---|---|
| volts | no | number | Volts value to write, expressed as a decimal number. If not specified, the "volts" property from the configuration will be used. |
| format | yes | string | Data format of the value written to VOUT_COMMAND. Currently the only supported format is "linear". |
| exponent | no | number | Exponent value for linear data format. Can be positive or negative. If not specified, the exponent value will be read from VOUT_MODE. |
| is_verified | no | boolean (true or false) | If true, the updated value of VOUT_COMMAND is verified by reading it from the device. If false or not specified, the updated value is not verified. |
true
{
"comments": [ "Set output voltage. Get volts value from configuration.",
"Get exponent from VOUT_MODE." ],
"pmbus_write_vout_command": {
"format": "linear"
}
}
{
"comments": [ "Set output voltage. Explicitly specify volts and exponent.",
"Verify value was successfully written to VOUT_COMMAND." ],
"pmbus_write_vout_command": {
"volts": 1.03,
"format": "linear",
"exponent": -8,
"is_verified": true
}
}