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6.3.2End Power Transfer Packet (0x02)

Table 6-3 defines the format of the message contained in an End Power Transfer Packet.

Table 6-5: End Power Transfer

End Power Transfer Code This field identifies the reason for the End Power Transfer request, as listed in Table 6-6. The Power Receiver shall not transmit End Power Transfer Packets that contain any of the values that Table 6-6 lists as reserved.

Table 6-6: End Power Transfer values

(Informative) It is recommended that the Receiver uses the End Power Transfer values listed in Table 6-6 as follows:

0x00 The Receiver may use this value if it does not have a specific reason for terminating the power transfer, or if none of the other values listed in Table 6-6 is appropriate.

0x01 The Receiver should use this value if it determines that the battery of the Mobile Device is fully charged. On receipt of an End Power Transfer Packet containing this value, the Transmitter should set any “charged” indication on its user interface that is associated with the Receiver.

0x02 The Receiver may use this value if it has encountered some internal problem, e.g. a software or logic error.

0x03 The Receiver should use this value if it has measured a temperature within the Mobile Device that exceeds a limit.

0x04 The Receiver should use this value if it has measured a voltage within the Mobile Device that exceeds a limit.

0x05 The Receiver should use this value if it has measured a current within the Mobile Device that exceeds a limit.

0x06 The Receiver should use this value if it has determined a problem with the battery of the Mobile Device.

0x07 The Receiver should use this value if it desires to renegotiate a Power Transfer Contract.

0x08 The Receiver should use this value if it determines that the Transmitter does not respond to Control Error Packets as expected (i.e. does not increase/decrease its Primary Cell current appropriately).

6.3.3Control Error Packet (0x03)

Table 6-7 defines the format of the message contained in a Control Error Packet.

Table 6-7: Control Error

Control Error Value The (two’s complement) signed integer value contained in this field ranges between

–128…+127 (inclusive), and provides input to the Operating Point controller of the Power Transmitter. See Sections 5.2.3.1 and 5.3.4 for more details. Values outside the indicated range are reserved and shall not appear in a Control Error Packet.

6.3.4Received Power Packet (0x04)

Table 6-8 defines the format of the message contained in a Received Power Packet.

Table 6-8: Received Power

Received Power Value The unsigned integer contained in this field indicates the average amount of power that the Power Receiver receives through its Interface Surface, in the time window indicated in the Configuration Packet. This amount of power is calculated as follows:

( ) ( )

Here, Maximum Power and Power Class are the values contained in the Configuration Packet (see Section 6.3.7). Annex D defines how a Power Receiver shall determine its Received Power .

6.3.5Charge Status Packet (0x05)

Table 6-9 defines the format of the message contained in a Charge Status Packet.

Table 6-9: Charge Status

Charge Status Value If the Mobile Device contains a rechargeable energy storage device, the unsigned integer contained in this field indicates the charging level of that energy storage device, as a percentage of the fully charged level. For clarity, the value 0 means an empty energy storage device, and the value 100 means a fully charged energy storage device. If the Mobile Device does not contain a rechargeable energy storage device, or if the Power Receiver cannot provide charge status information,14 this field shall contain the value 0xFF. All other values are reserved and shall not appear in the Charge Status Packet.

14Note that the Charge Status Packet is optional, which means that the Power Receiver may elect not to send the Charge Status Packet.

6.3.6Power Control Hold-off Packet (0x06)

Table 6-8 defines the format of the message contained in a Power Control Hold-off Packet.

Table 6-10: Power control hold-off

Power Control Hold-off Time The unsigned integer contained in this field contains the amount of time in milliseconds, which the Power Transmitter shall wait prior to making adjustments to the Primary Cell current after receipt of a Control Error Packet.

6.3.7Configuration Packet (0x51)

Table 6-11 defines the format of the message contained in a Configuration Packet.

Table 6-11: Configuration

Power Class This field contains an unsigned integer value that indicates the Power Receiver’s Power Class. Power Receivers that comply with this version 1.1.1 of the System Description Wireless Power Transfer, Volume I, Part 1, shall set this field to 0.

Maximum Power Apart from a scaling factor, the unsigned integer value contained in this field indicates the maximum amount of power, which the Power Receiver expects to provide at the output of the rectifier. This maximum amount of power is calculated as follows:

Prop If this bit is set to ZERO, the Power Transmitter shall control the power transfer according to the method defined in Section 5.2.3.1. If this bit is set to ONE, the Power Transmitter may control the power transfer according to a proprietary method instead of the method defined in Section 5.2.3.1. However, if this bit is set to ONE, the Power Transmitter shall continue to ensure that the received Control Error Packets comply with the timings defined in Section 5.2.3. (Informative) This implies that a Power Transmitter terminates the power transfer if it times out when waiting for a Control Error Packet. Moreover, this implies that setting the Prop bit to ONE does not relieve the Power Receiver from transmitting Control Error Packets on a regular basis. Finally, if the Prop bit is set to ZERO, the Power Transmitter could still decide to abort the power transfer based on information contained in a Proprietary Packet.

Reserved These bits shall be set to ZERO.

Count This field contains an unsigned integer value that indicates the number of optional configuration Packets that the Power Receiver transmits in the identification & configuration phase.

Window Size The unsigned integer contained in this field indicates the window size for averaging the Received Power, in units of 4 ms. See also Figure 5-10(b) in Section 5.3.4.

Window Offset The unsigned integer contained in this field indicates the interval between the window for averaging the Received Power and the transmission of the Received Power Packet., in units of 4 ms. See also Figure 5-10(b) in Section 5.3.4.

6.3.8Identification Packet (0x71)

Table 6-12 defines the format of the message contained in an Identification Packet.

Table 6-12: Identification

Major Version The combination of this field and the Minor Version field identifies to which revision of the System Description Wireless Power Transfer the Power Receiver complies. The Major Version field shall contain the binary coded digit value 0x1.

Minor Version The combination of this field and the Major Version field identifies to which minor revision of the System Description Wireless Power Transfer the Power Receiver complies. The Minor Version field shall contain the binary coded digit value 0x1.

Manufacturer Code The bit string contained in this field identifies the manufacturer of the Power Receiver, as specified in [PRMC].

Ext If this bit is set to ZERO, the bit string Manufacturer Code || Basic Device Identifier

identifies the Power Receiver. If this bit is set to ONE, the bit string Manufacturer Code || Basic Device Identifier || Extended Device Identifier

identifies the Power Receiver (see also Section 6.3.9).

Basic Device Identifier The bit string contained in this field contributes to the identification of the Power Receiver. A Power Receiver manufacturer should ensure that the combination of Basic Device Identifier and Manufacturer ID is sufficiently unique. Embedding a serial number of at least 20 bits in the Basic Device Identifier is sufficient. Alternatively, using a (pseudo) random number generator to dynamically generate part of the Basic Device Identifier is sufficient as well, provided that the generated part complies with the following requirements:

The generated part shall comprise at least 20 bits.

All possible values shall occur with equal probability.

The Power Receiver shall not change the generated part while the Power Signal is applied.

The Power Receiver shall retain the generated part for at least 2 s if the Power Signal is interrupted or removed.

(Informative) These requirements ensure that the scanning procedure of a type B1 Power Transmitter proceeds correctly; see also Annex C.2.

6.3.9Extended Identification Packet (0x81)

Table 6-13 defines the format of the message contained in an Extended Identification Packet.

Table 6-13: Extended Identification

Extended Device Identifier The bit string contained in this field contributes to the identification of the Power Receiver. See Section 6.3.8