Moto Mods Firmware: Battery Protocol¶

Overview¶

The Battery protocol allows the Moto Z to inquire about the battery on the Moto Mod. The data includes battery voltage, temperature and capacity.

To provide and receive power from the Moto Z, the Moto Mod is required to support the Power Transfer Protocol.

Hardware Manifest¶

Hardware Manifest files reside in apps/greybus-utils/manifests, one should be created for your unique project.

0x08 is the identifier for the Battery protocol.

Two entries are necessary for Battery, one for the Interface and one for the Bundle.

To support Charge Only mode, the Battery protocol must be in the Bundle with the Power Transfer protocol. If any other protocols are included in the bundle with Power Transfer and Battery, the Moto Mod will not be supported in Charge Only mode.

; Battery interface on CPort XX
[cport-descriptor XX]
bundle = YY
protocol = 0x08

; Battery related Bundle YY
[bundle-descriptor YY]
class = 0x08

XX shall be a unique integer (within your hardware manifest) defining which CPort is used for Battery.

YY shall be a unique integer (within your hardware manifest) which Bundle the Battery CPort is a member of.

Implementation¶

The Low level Battery device driver is specific to the hardware and reports current battery state upon requests.

Files¶

nuttx/include/nuttx/device_battery.h

This file defines the device_battery_type_ops structure and provides the glue to the Greybus Battery channel.

nuttx/configs/ara/bridge/src/battery_dummy.c

This file provides the starting point for your development. It should be copied into nuttx/configs/PROJECT/src for your specific Project and modified.

Methods¶

A battery device driver must implement methods defined in the device_battery_type_ops structure.

Reporting battery technology type: get_technology¶

The get_technology function reports the technology type of the Moto Mod battery from a set of defined types.

int (*get_technology)(struct device *dev, uint32_t *tech)

Parameters
`dev`	Pointer to structure of device data
`tech`	The output value is battery technology, based off a set of defined values:
`tech`	`GB_BATTERY_TECH_UNKNOWN GB_BATTERY_TECH_NiMH GB_BATTERY_TECH_LION GB_BATTERY_TECH_LIPO GB_BATTERY_TECH_LiFe GB_BATTERY_TECH_NiCd GB_BATTERY_TECH_LiMn`	`0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006`
Return
`int`	0 on success, negative errno on error

Reporting battery charging status: get_status¶

The get_status function reports the current charging status of the Moto Mod battery.

int (*get_status)(struct device *dev, uint16_t *status)

Parameters
`dev`	Pointer to structure of device data
`status`	The output value is battery status
Return
`int`	0 on success, negative errno on error

Reporting battery voltage: get_voltage¶

The get_voltage function reports an accurate reading of the Moto Mod battery voltage.

int (*get_voltage)(struct device *dev, uint32_t *voltage)

Parameters
`dev`	Pointer to structure of device data
`voltage`	The output value is battery voltage in microvolts
Return
`int`	0 on success, negative errno on error

Reporting battery current: get_current¶

The get_current function reports an accurate reading of the current being currently supplied or drawn from the Moto Mod battery.

int (*get_current)(struct device *dev, int *current)

Parameters
`dev`	Pointer to structure of device data
`current`	The output value is battery current in microamps
Return
`int`	0 on success, negative errno on error

Reporting battery capacity in percentage: get_percent_capacity¶

The get_percent_capacity function reports Moto Mod battery percent capacity.

int (*get_percent_capacity)(struct device *dev, uint32_t *percent_cap)

Parameters
`dev`	Pointer to structure of device data
`percent_cap`	The output value is battery level in percent
Return
`int`	0 on success, negative errno on error

Reporting battery total capacity: get_total_capacity¶

The get_total_capacity function reports total Moto Mod battery capacity.

int (*get_total_capacity)(struct device *dev, uint32_t *total_cap)

Parameters
`dev`	Pointer to structure of device data
`total_cap`	The output value is battery total design capacity in mAh
Return
`int`	0 on success, negative errno on error

Reporting battery temperature: get_temperature¶

The get_temperature function reports current temperature of the Moto Mod battery.

int (*get_temperature)(struct device *dev, int *temperature)

Parameters
`dev`	Pointer to structure of device data
`temperature`	The output value is battery temperature in 0.1 Celsius
Return
`int`	0 on success, negative errno on error

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