GS2101M IP2WiFi Adapter Command Reference Guide
1VV0301499
Rev. 2.0
50
2019-08-05
shows the timing diagram for MCU Read (>1024 Bytes) to GS node.
Figure 8 MCU Read (>1024 Bytes) to GS Node
3.2.2.3 Annexure - HI Frame Format (From Host)
All messages carried over the Host Interface have a common format. They are composed
of a HI header, and parameters depending on the header. HI frames are composed, in
addition to the HI header and parameters, of a start delimiter and a HI HEADER checksum.
This format is defined in
.
The Start-of-frame delimiter is the single-byte value 0xA5, used to ensure synchronization
at the frame level. The driver starts the reception process when it recognizes the delimiter.
The length of the delimiter has been reduced to 1 byte to avoid alignment problems when
waiting for the start element. However, no provisions are made to ensure that the
subsequent data stream does not contain a byte with value 0xA5, so it is possible for the
driver to mistake a data byte for a delimiter. Therefore, a header checksum has been added
to ensure correct synchronization. A single checksum byte is used, computed as the 1’s
complement of the 8-bit long (modulo-256) sum of all the bytes of the HI HEADER (not
including the Start delimiter). Note that each byte is independently added to the sum, as an
integer between 0 and 255, without regard for its significance within its own data field.
Figure 9 HI Frame Format (From Host Side)
1
3 4
5 6
8
2
7
0
READ_REQUEST from HOST
DATA
CMD PHASE
RESPONSE PHASE
DATA PHASE
READ_RESPONSE
DATA_HEADER
GPIO37 goes HIGH when GS is ready with
READ_RESPONSE
GPIO37 goes LOW after receiving
4bytes of READ_REQUEST.
GPIO goes LOW after 16+X bytes , when
GS is sending more than 1024bytes to
MCU (Where X= actual data size – 1024
Byte).
