1# power_sequencer 2 3## Description 4 5A power sequencer device within a chassis. 6 7The power sequencer is responsible for performing the following tasks on a set 8of [voltage rails](rail.md): 9 10- Power the rails on in the correct order 11- Monitor the rails for a [pgood fault](../pgood_faults.md) 12- Power off the rails in the correct order 13 14Note that some voltage rails may automatically power on/off without the power 15sequencer, but they might still be monitored for pgood faults. 16 17[Named GPIOs](../named_gpios.md) are used for the following: 18 19- Power the sequencer on and off 20- Monitor the power good signal from the sequencer. This signal is true when all 21 rails are providing the expected voltage level. 22 23## Properties 24 25| Name | Required | Type | Description | 26| :---------------------- | :-----------------: | :-------------------------------- | :---------------------------------------------------------------------------------------------------------------------------- | 27| comments | no | array of strings | One or more comment lines describing this power sequencer. | 28| type | yes | string | Power sequencer type. Specify one of the following supported types: "UCD90160", "UCD90320", "gpios_only_device". | 29| i2c_interface | see [notes](#notes) | [i2c_interface](i2c_interface.md) | I2C interface to this power sequencer. | 30| power_control_gpio_name | yes | string | Named GPIO for turning this power sequencer on and off. | 31| power_good_gpio_name | yes | string | Named GPIO for reading the power good signal from this power sequencer. | 32| rails | see [notes](#notes) | array of [rails](rail.md) | One or more voltage rails powered on/off and monitored by this power sequencer. The rails must be in power on sequence order. | 33 34### Notes 35 36- The "i2c_interface" and "rails" properties are required if the "type" is 37 "UCD90160" or "UCD90320". They are ignored if the "type" is 38 "gpios_only_device". 39 40## Example 41 42```json 43{ 44 "type": "UCD90320", 45 "i2c_interface": { "bus": 3, "address": "0x11" }, 46 "power_control_gpio_name": "power-chassis-control", 47 "power_good_gpio_name": "power-chassis-good", 48 "rails": [ 49 { 50 "name": "VDD_CPU0", 51 "page": 11, 52 "check_status_vout": true 53 }, 54 { 55 "name": "VCS_CPU1", 56 "presence": "/xyz/openbmc_project/inventory/system/chassis/motherboard/cpu1", 57 "gpio": { "line": 60 } 58 } 59 ] 60} 61``` 62