Kv260 single board PS control setting IIC switch chip

stay KV260 There is one board IIC The control of the 4 choose 1 Circuit switch chip TAC9546A, Use through IIC Set the chip selection IIC passageway ,PS Output one way IIC Can be controlled 4 road IIC equipment .

IIC agreement

Introducing IIC SWITCH Before , Just a quick introduction IIC agreement , How to use PL Realization IIC Control needs to be right IIC The agreement is very familiar with , If you use PS control IIC, Only need to IIC Just understand the agreement .

IIC Protocols are commonly used , A friend I don't know , It is recommended to refer to two documents, one is Xilinx Of pg090, The other is Philips Semiconductors I2C-bus Specification.

IIC The communication between bus master and slave devices mainly includes 4 part ：
• START
• Slave Address
• Data Transfer
• STOP

Usual IIC In communication Data Transfer Send address first and then send data , but IIC SWITCH chip TAC9546A There are some differences , Finished sending Slave Address Then send data directly , When reading operations , Finished sending Slave Address Then read the data directly , In the next section, I'll talk about .

IIC SWITCH

TAC9546A

stay KV260 adopt HDA Pin connection TAC9546A, Use TAC9546A Output 3 Channels , Connect two ways respectively MIPI Camera and raspberry pie camera .

Write register

Through to IIC SWITCH Write data in the control register , Choose IIC passageway B3、B2、B1、B0 Respectively corresponding to the channel 3、 passageway 2、 passageway 1 And channel 0 Four way output . For example, select a channel 2 Write on 0x02.

adopt IIC When sending the write register command , Send... First Slave Address, Then send the value to be written in the control register .Slave Address Middle and high 4 Bit fixation , low 3 position A2A1A0 Configurable , Again KV260 Set in the for 100, therefore Slave Address by 1110100,0x74.

Read register

After writing the register , To verify whether the writing is normal , Read register value . Send first when reading Slave Address, Then receive the control register value .

PS Add IIC

stay KV260 Use in EMIO, instead of MIO, Need to be in vivado Make the following settings in ：

iic_sda and iic_scl All use IOBUF,iic_scl_io and iic_sda_io Use inout Port settings .

  IOBUF iic_scl_iobuf
       (.I(iic_scl_o),
        .IO(iic_scl_io),
        .O(iic_scl_i),
        .T(iic_scl_t));
  IOBUF iic_sda_iobuf
       (.I(iic_sda_o),
        .IO(iic_sda_io),
        .O(iic_sda_i),
        .T(iic_sda_t));

PS Reading and writing IIC SWITCH

Reading and writing IIC when , You can use polling mode and interrupt mode , Because the polling mode is relatively simple , So this design uses polling mode .

Write IIC SWITCH register ：

int i2c_switch_write(XIicPs *InstancePtr, u8 IIC_ADDR, u8 Data)
{
	int Status;
	u8 wr_data = Data;
	Status = XIicPs_MasterSendPolled(InstancePtr, &wr_data, 1, IIC_ADDR);
	while (XIicPs_BusIsBusy(InstancePtr));
	return Status;
}

read IIC SWITCH register ：

char i2c_switch_read(XIicPs *InstancePtr, u8 IIC_ADDR)
{
	u8 rd_data;
	XIicPs_MasterRecvPolled(InstancePtr, &rd_data, 1, IIC_ADDR);
	while (XIicPs_BusIsBusy(InstancePtr));
	return rd_data;
}

ILA debugging

stay PL Pass through ILA Observe IIC Read write timing .

Write register ：Slave Address by 0x74, Start high bit Late onset low bit, Finished sending 7bitSlave Address1110100 after , send out 0, This bit indicates a write operation , wait for IIC SWITCH send out ACK, Then send the data 0x02, wait for ACK Post send stop bit .

Read register ：Slave Address by 0x74, Start high bit Late onset low bit, Finished sending 7bitSlave Address1110100 after , send out 1, This bit indicates a read operation , wait for IIC SWITCH send out ACK, Then send the data 0x02, No response , Send stop bit .

matters needing attention

Use PS control IIC when , Be especially important SlaveAddress, This use 1110100, Convert to sixteen progressive digits 0x74, Don't write as 8bit11101000, There is no such chip ACK.