Data Sheet

iEthernet

W5200

/* update destination_ptr */

dst_address += upper_size;

/* copy left_size bytes of gSn_RX_BASE to destination_address */

left_size = len – upper_size;

memcpy(gSn_RX_BASE, dst_address, left_size);

}

else

{

copy len bytes of source_ptr to destination_address */

memcpy(src_ptr, dst_ptr, len);

}

/* increase Sn_RX_RD as length of len */

Sn_RX_RD += len;

/* set RECV command */

Sn_CR = RECV;

}

ESTABLISHMENT: Check send data / Send process

The size of the transmit data cannot be larger than assigned internal TX memory of

Socket n . If the size of transmit data is larger than configured MSS, it is divided by

size of MSS and transmits. To transmit the next data, user must check the completion

of prior SEND command. An error may occur if the SEND command executes before

completion of prior SEND command. The larger the data size, the more time to

complete the SEND command. So the user should properly divide the data to transmit.

To check the completion of the SEND command, it should be check that the send data

length is equal with the actual sent data length. The actual sent data length is

calculated by the difference of the Sn_TX_RD before and after performing the SEND

command. If the actual sent data is less than the send data length, the SEND command

is retried for sending the left data. The send process is therefore completed the

SENDwhen the sum of the actual sent data is equal the send data length. A simple

example of the send process is as below

Ex) Send Data Length Size= 10,

1) Execute SEND Command with send data length

2) Calculate the actual sent data length

If the actual sent data length is 7 (= Sn_TX_RD_after_SEND-Sn_TX_RD_befor_SEND),

the left Data length= 3

3) Retry SEND Command until the sum of the actual sent data length is same the

send data length.

Note: Don’t copy data until the sum of the actual sent data length is the send data length.