Rules For Output Messages - STMicroelectronics SPC572L series Reference Manual

RM0400
nex_mseo_b[1:0]=01
nex_mseo_b[1:0]=01
nex_mseo_b[1:0]=01
The dual pin MSEO option is more robust that the single pin option. Termination of the
current message may immediately be followed by the start of the next message on the
consecutive clocks. An extra clock to end the message is not necessary as with the one
MSEO pin option. The dual pin option also allows for consecutive "End Packet" states. This
can be an advantage when small, variable sized packets are transferred.
Note: The "End Message" state may also indicate the end of a variable-length packet as well as
the end of the message when using the dual pin option.
66.19

Rules for output messages

Class 3 compliant embedded processors must provide messages via the auxiliary port in a
consistent manner as described below:
•
A variable-sized packet within a message must end on a port boundary.
•
A variable-sized packet may start within a port boundary only when following a fixed
length packet. (If two variable-sized packets end and start on the same clock, it is
impossible to know which bit is from the last packet and which bit is from the next
packet.)
•
Whenever a variable-length packet is sized such that it does not end on a port
boundary, it is necessary to extend and zero fill the remaining bits after the highest-
Figure 1185. Dual pin MSEO transfers
nex_mseo_b[1:0]=10
nex_mseo_b[1:0]=11
End
Message
nex_mseo_b[1:0]=00
nex_mseo_b[1:0]=11
End
Packet
DocID027809 Rev 4
nex_mseo_b[1:0]=11
Idle
MDO: Invalid
nex_mseo_b[1:0]=00
nex_mseo_b[1:0]=11
nex_mseo_b[1:0]=01
nex_mseo_b[1:0]=00
e200z215An3 Nexus 3 Module
nex_mseo_b[1:0]=10
Start
Message
nex_mseo_b[1:0]=00
Normal
Transfer
nex_mseo_b[1:0]=00
1977/2058
1982