UM0934 Datasheet, PDF (38/113 Pages) STMicroelectronics – ST7570 S-FSK power line networking System-on-Chip

Host interface
UM0934
As described in Section 2.2, the ST7570 protocol stack implemented in compliance with [2]
can be accessed at the physical layer (PHY mode) or at the MAC layer (MAC mode).
Several commands of the host interface may present a different format and behavior
according to the selected mode.
Local frames
The format of the frame used in the local communication between the ST7570 and the
external host is graphically represented in Figure 15:
Figure 15. Local frame format
STX
Length Command
Code
DATA
Checksum
The frame fields are described in Table 10:
Table 10. Local frame format
Field
Byte length Value
Description
STX
1
02h Start of text delimiter
Length
1
3..250 Byte length of fields: command + data + checksum
Command code
Data
1
0..247
0..FFh Command code
Data field (247 byte max)
Checksum
2
The checksum of the local frame is the result of the addition
of the elements of the frame, from length up to the last data
byte, or up to the command byte if there is no data byte.
Byte endianness for fields (data and checksum) with a length greater than one byte is:
● Data field: structured in sub-fields in accordance with command code specifications
described in 5.3. Sub-fields with a length greater than one byte are sent LSByte first
unless otherwise specified
● Checksum field: is sent LSByte first.
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Doc ID 17389 Rev 2