P9221-R3 Datasheet

© 2017 Integrated Device Technology, Inc.

26

October 20, 2017

10.2 Reading Data Sent from the P9242-R3 to the P9221-R3

The 9221-R3 can receive 2 bytes of information at a time. When the P9221-R3 receives the data from the P9242-R3, it will generate an interrupt

to the external MCU on the receiver by pulling down the interrupt pin (INT

̅̅̅̅). Because interrupts can be generated for multiple reasons, the MCU

can respond to the interrupt and read the data received flag in bit 4 in Status register 0034HEX to confirm that the interrupt is generated because

of new incoming data. The data received flag (bit 4 in register 0034HEX) is set to 1 when there is new incoming data. After confirming that new

data is available to read, the external MCU can read incoming user data registers 0058HEX and 0059HEX.

Table 10. Registers Used for Reading User Data from the P9242-R3

Register Name

Register Address

Status Register

0034HEX

Command Register

004EHEX

Clear Interrupts

0056HEX

User Incoming Data

0058HEX and 0059HEX

After reading the data, the external MCU on the receiver should clear the interrupt by writing 1 to bit 5 in Command register 004EHEX and clear

the data received flag in bit 4 in Status register 0034HEX by writing 1 to bit 4 in register 56HEX. If the external MCU on the receiver does not

handle interrupts, it should constantly poll bit 4 in register 0034HEX to check whether there is any new incoming data.

If the external MCU on the receiver does not read the data soon after the interrupt is received, there is a risk that the data will become corrupted

because of new incoming data. The P9221-R3 does not reject new incoming data because old data was not read by the MCU on the receiver.

The user can implement a higher-level handshaking protocol between the external MCU on the transmitter and the receiver to avoid data

corruption.