User Guide

DisplayPort Tx IP Configuration
Microsemi Proprietary and Confidential UG0935 User Guide Revision 2.0 11
7 DisplayPort Tx IP Configuration
7.1 HPD Detection
DisplayPort Tx IP detects the input HPD signal to check the status of the attached DisplayPort Sink
device. The HPD event includes three types.
• HPD assertion, it means DisplayPort Sink device is connected.
• HPD de-assertion, it means DisplayPort Sink device is disconnected.
• HPD interrupt, it means the DisplayPort Sink device's status has changed.
When the HPD event is detected and interrupt is enabled, DisplayPort Tx IP could output a pulse on the
int_o port and indicates the interrupt type on interrupt register 0x0188.
7.2 Transmit AUX Request Transaction
To transmit a Native Writing AUX Request transaction, DisplayPort Tx application software should do the
following steps:
1. Write all the writing bytes into register 0x010C, write one byte for each writing operation.
2. Write the DPCD address into register 0x0104.
3. Write (WritingBytesNum-1) into register 0x0108.
4. Write ((WritingBytesNum << 16) | (0x00000001 << 8) | 0x00000008) into registers 0x0100.
To transmit a Native Reading AUX Request transaction, DisplayPort Tx application software should do
the following steps:
1. Write the DPCD address into register 0x0104.
2. Write (ReadingBytesNum-1) into register 0x0108.
3. Write ((0x00000000<<16) | (0x00000001<<8) | 0x00000009) into registers 0x0100.
To transmit an I2C-Over-AUX Writing Request transaction, DisplayPort Tx application software should do
the following steps:
1. Write all the writing bytes into register 0x010C, write one byte for each writing operation.
2. Write the DPCD address into register 0x0104.
3. Write (WritingBytesNum-1) into register 0x0108.
4. Write ((WritingBytesNum << 16) | (0x00000001 << 8) | (MOT<<2) | 0x00000000) into registers
0x0100.
To transmit an I2C-Over-AUX Reading Request transaction, DisplayPort Tx application software should
do the following steps:
1. Write the DPCD reading address into register 0x0104.
2. Write (ReadingBytesNum-1) into register 0x0108.
3. Write ((0x00000000<<16) | (0x00000001<<8) | (MOT<<2) | 0x00000001) into registers into 0x0100.
7.3 Receive AUX Reply Transaction
After sending an AUX Request transaction to the DisplayPort Sink device, DisplayPort Source
application software should wait for the AUX Reply transaction. When the AUX Reply is arrived and
interrupt is enabled, DisplayPort Tx IP could output an interrupt signal and record this event in the
interrupt register.
To read the received AUX Reply transaction from DisplayPort Tx IP, software should do the following
steps:
1. Read register 0x012C to know AUX Reply transaction length AuxReplyByteNum.
2. Read register 0x0124 AuxReplyByteNum times to get all the AUX Reply Transaction bytes.
3. Software checks the Reply type by checking the first reading transaction byte bit [7:4], it could be
AUX ACK, NACK, or AUX DEFER. Bit [3:0] is reserved.
4. If AuxReplyByteNum > 1, the followed bytes are reading data from the DPCD registers.