AT+i Programmer's Manual - SE Spezial-Electronic AG

23.3 Software Flow Control During A Socket Send
Flow Control
When a WAIT control is sent to the host during a socket send (AT+iSSND) command, it
is automatically followed by an RP4 socket status report in the following syntax:
I/(, , … ,)
See the AT+iRP command for a full description.
While the host is waiting for the CONTINUE control, it may analyze the sockets‘ input
buffer status. If the host detects a need to execute a socket receive command to empty one
or more socket input buffers, it may escape the current SSND command by issuing a
‗Pause’ sequence immediately after receiving the ‗CONTINUE‘ control.
The ‗Pause’ sequence is defined as: half a second of silence followed by (---) (three
consecutive minus sign characters). iChip responds by prematurely terminating the SSND
command, including flushing the current socket if the (%) flag is specified. Following
this, the I/OK message is issued and the host may issue the required SRCV command in
addition to any other operations it needs to execute. The host may return to the preempted
socket at any time and issue a new SSND command to send out the balance of
data.