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TC1796
Peripheral Units (Vol. 2 of 2)
Micro Second Channel (MSC)
User’s Manual
21-19
V2.0, 2007-07
MSC, V2.0
21.1.2.4 Downstream Counter and Enable Signals
During downstream channel operation, a 7-bit downstream counter DSS.DC is counting
FCL shift clock periods. With the loading of the shift register, the downstream counter is
reset to 00
H
and started for counting up to the end of the downstream frame (end of
passive phase).
In Triggered Mode, the downstream counter stops counting at the end of the passive
phase and waits until a new downstream frame is started.
In repetition mode, the downstream counter does not stop at the end of the passive
phase but is reset and starts counting up again with the next frame, independently
whether a data frame, command frame, or passive time frame is started as next frame.
shows an example of downstream channel data frame transmission. In this
example, the selection bit for the SRL active frame is enabled (ENSELL = 1), and the
selection bit for the SRH active frame is disabled (ENSELL = 0). With loading of the shift
register SRL/SRH, the downstream counter is reset and then starts counting up with
each FCL clock until the end of the passive phase is reached. ENL is set to high level at
the beginning of the SRL active frame selection bit.
Figure 21-12 Shift Clock Counting: Data Frame with ENSELL = 1 and ENSELH = 0
MCT05806
Passive
Phase
ENH
t
FCL
Downstream Frame
SRL Active Phase
SRH Active Phase
1
0
2
m+1
ENL
FCL
State of
DSS.DC
SRL.0
0
SRL.m
m
SO
SRH.0
m+2
m+3
DC
max
SRL/SRH
Loading
SRL.1
3
SRH.n
SRH.1
m+4