TC1796
Peripheral Units (Vol. 2 of 2)
Micro Link Interface (MLI)
User’s Manual 23-72 V2.0, 2007-07
MLI, V2.0
Figure 23-49 Loop Delay Measurement
To adjust the generated parity delay in the local transmitter and in the remote receiver,
the following steps are necessary:
• Send a dummy frame to the receiver for measuring the loop delay. This frame should
not lead to internal data move actions in the receiver, so a parity error can be
simulated in the transmitter. The receiver has a fixed even parity scheme, whereas
the transmitter can be programmed either for even or for odd parity. Programming
odd parity before sending a frame will generate a (dummy) frame that will be
discarded by the receiver (assuming a correct transfer). For a dummy frame, it is
recommended to use a data frame with disabled Automatic Data Mode in the receiver
(RCR.MOD = 0).
• The receiver delay RCR.DPE being 0 after a module reset, the transmitter can
measure the loop delay and the receiver discards the frame (without modification of
DPE, there is no difference in time between a frame with or without a parity error
having been detected). The value given by TSTATR.RDC indicates how many TCLK
cycles are necessary for a control handshake. This value should be incremented by
a value DELTA (value see below) and written to TCR.MDP.
• The transmitter parity has to be programmed to even parity to be able to generate
frames that are not discarded by the receiver.
• Programming the receiver delay for parity error (RCR.DPE) to a value bigger than
DELTA will lead to a value of TSTATR.RDC bigger than TCR.MDP if the receiver
detects a parity error. The value of DPE in the remote receiver is modified by the local
transmitter by sending a Command Frame in pipe 1 with the desired value. The
difference between TSTATR.RDC and TCR.MDP allows a certain timing tolerance
between local transmitter and remote receiver.
MCT05894_mod
TVALID
RDC
RREADY
TCLK
012n-1n
RREADY Window (best case)
Loop Delay
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