Data Sheet

ISM4343 Specification
DOC-DS-20074-5.3
Inventek Systems
Page 16
6.3.2 SPI Command Phase:
The Command Phase indicates the eS-WiFi module is ready to accept an IWIN AT Command.
The command must include all delimiters and data for the command.
Ex. S3=0010\r0123456789
The command must also be sent as one continuous SPI cycle, that is SSN must stay low for the
complete command, delimiters, and data.
The Host will initiate a SPI cycle (lower SSN) and clock out the command, delimiters and
associated data and raise the NSS signal to indicated that the all data has be sent. As result of the
NNS raising the eS-WiFi module will lower the CMD/DATA READY pin to signal the end
Command Phase.
The data that will be clocked back to the Host will be 0x15 (NAK).
6.3.3 SPI Endian Example:
The data is in little endian (0x15 0x15 0x0A 0x0D 0x20 0x3E) and needs to be converted back to
big endian with the leading 0x15’s removed. Please remember that this is a 16-bit interface so
the endian conversion is done one 16-bit at a time.
The endian requirement extends to the command being sent to the module. So a “I?\r\x0A”
command would be sent as 0x3F 0x49 0x0A 0x0D.