Data Sheet

iEthernet

W5200

READ Processing

The READ Processing Sequence Diagram is shown in Figure 20. The READ processing is

entered by driving CSn low, followed by the Address, the OP code, the Data Length and

the Dummy data byte on MOSI. And then W5200 read the data byte on MISO. The Address,

the OP/Data Length Sequence Diagram and the Data are shown in Figure 19. The OP code

(OP) is defined type of the READ OP and WIRTE OP. On OP = 0, the read operation is

selected. Otherwise, On OP = 1, the write operation is selected.

In W5200 SPI mode, the Byte READ processing and the burst READ processing are provided.

The Byte READ processing takes 4 instructions which is consist of the 16-bit Address, the

1-bit OP code(0x0), the 15-bit Data length and 8-bit Data. Otherwise, The Burst READ

processing only takes the Data instruction after the setting of the burst read processing.

To distinguish between the Byte READ and the burst READ processing, the Data length is

used. If the Data length is ‘1,’ the Byte READ processing is operated. Otherwise, the Burst

READ Processing is operated when the Data length is more than two. The MISO pin should

be selected by driving MISO low after the falling edge of the CSn.

Figure 21 READ Sequence

/* Pseudo Code for Read data of 8bit per packet */

#define data_read_command 0x00

uint16 addr; // Address : 16bits

int16 data_len; // Data length :15bits

uint8 data_buf[]; // Array for data

SpiSendData(); // Send data from MCU to W5200

SpiRecvData(); // Receive data from W5200 to MCU

{

ISR_DISABLE(); // Interrupt Service Routine disable