User's Manual

Table Of Contents
Direct Socket Interface
AT+i Programmer‘s Manual Version 8.32 13-7
13.7 +iSSND[%] Send A Byte Stream to A Socket
Syntax:
AT+iSSND[%]:<hn>,<sz>:<stream>[<checksum>]
Sends a byte stream of size sz to the socket specified by
the socket handle hn.
Parameters:
<hn>
A TCP/UDP socket handle of an open socket
<sz>
The exact size of the byte stream that follows
<stream>
A byte stream of size sz to be sent to the specified
socket. When iChip is in checksum mode (
CKSM set to
1), the socket is UDP or when sending data over an SSL
socket, sz is limited to 2048 bytes.
<checksum>
A two-byte checksum. Checksum is calculated by
summing all the characters in stream modulo 65536 and
taking two‘s complement of the result. Checksum is sent
as big-endian. This parameter must be appended by the
host application when iChip is in checksum mode.
Command Options:
<hn>
Must have been obtained by a previous execution of an
AT+iSTCP or AT+iSUDP command during the current
Internet mode session. Or a socket accepted by a
listening socket.
<sz>
Regular TCP socket: 0..4GB
SSL Socket, Checksum mode or UDP: 0..2048
<stream>
An 8-bit byte stream of exactly size sz. If sz is larger
than 256 bytes, iChip assumes host flow control.
Depending on the setting of the FLW parameter, the
flow control mode is either software or hardware.
Under software flow control mode, the host processor
must respond to iChip‘s flow control characters. The
flow control protocol is detailed in the ―Host iChip
Software Flow Control‖ section.
Under hardware flow control, the ~CTS/~RTS RS232
control signals must be connected and the host must
respond to iChip‘s ~CTS signal. The host may send data
only when the ~CTS signal is asserted (active low).
%
When the auto flush (%) flag is specified for a TCP
socket, the socket is automatically flushed immediately
after receiving the stream. Otherwise, data is transmitted
to the Internet only in integral quantities of the specified
Maximum Transfer Unit (MTU) or when the
AT+iSFSH