P9222-R/RN Datasheet

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May 5, 2022

6. Bi-directional User Data Communication

Note: The default firmware supports bi-directional user data communication.

In customer-end systems, the transmitter and receiver boards must have an external microcontroller (MCU) or leverage an existing

application processor to orchestrate bi-directional communication. Using the I2C communication, the MCU on the receiver board must load

the data into specific registers and trigger the communication. The P9222-R/RN sends the data to the P9235-RB using amplitude-shift keying

(ASK) modulation. The P9235-RB will receive the data and interrupt the MCU on the transmitter when the data is ready to be read. The

external MCU on the transmitter follows the same procedure to send the data to the P9222-R/RN. When new data is available to be read, the

P9222-R/RN will interrupt the external MCU on the receiver board.

Bi-directional user data communication is enabled only in the power transfer phase for the WPC standard. The external MCU on the receiver

board can read register 0x4C (bit 0) to determine whether the P9222-R/RN is in the power transfer phase.

See Figure 19 for a state diagram that shows the procedure that the external MCU on the receiver board must follow to send the user data

from the P9222-R/RN to the P9235-RB as described in “Transferring Data from the P9222-R/RN to the P9235-RB.” See Figure 20 for a state

diagram that shows the procedure that the external MCU must follow to read the data sent by the P9235-RB as described in “Reading Data

Sent from the P9235-RB to the

”.

6.1 Transferring Data from the P9222-R/RN to the P9235-RB

The external MCU on the receiver board should read bit 5 in register 0x4C to determine the status of the communication channel before initiating

a new transfer. If the communication channel is free, bit 5 in register 0x4E is 0. If the communication channel is busy, bit 5 in register 0x4E is

set to 1. The P9222-R/RN receiver supports sending up to 7 bytes of user data. The external MCU on the receiver should write the data that it

will send to the transmitter into the Outgoing User Data Registers (0x51 to 0x57) and set the Data Header register (0x50) accordingly.

Table 6.

Registers Used for Data Transmission from P9222-R/RN to P9235-RB

Register Name

Register Address

Command Register

0x4E

Data Header Register

0x50

Outgoing User Data Registers

0x51 to 0x57 (7 bytes)

System Mode register

0x4C

Power Transfer Phase Indicator

0x4C (bit 0)

The external MCU on the receiver should set bit 0 in the Command register 0x4E to 1b to trigger the communication after loading the user

data into the outgoing data registers and setting the data header for the correct number of bytes. If the receiver is sending 1 byte, 2 bytes,

and 3 bytes in the outgoing register, then the user would set the header register to 0x18, 0x28, and 0x38, respectively. After receiving the

communication trigger from the control register, the P9222-R/RN reads the data header register and outgoing data registers and constructs a

proprietary communication packet with a packet checksum. The communication packet is sent into the channel between two Control Error

Packets (CEP) using ASK modulation.

Figure 17 shows the timing diagram for the user data transfer from the P9222-R/RN to the P9235-RB.