NXP Semiconductors MPC5644A, Reference Manual, Page: 1222 / 1735

Decimation Filter
MPC5644A Microcontroller Reference Manual, Rev. 6
1222 Freescale Semiconductor
Figure 26-22. Examples of mixed cascaded and single blocks
26.5.16.1 Cascade freeze, stop, and configuration change procedures
To change a block configuration mode to or from cascade mode, the following safe procedures must be
observed:
• To modify a cascade combo, either to single or any other cascade combo combination, all the
cascade combo blocks must have their inputs disabled (using DECFILTER_MCR bit IDIS), in
order, from the Head to the Tail block. After a block IDIS bit has been set to 1 (one), one must wait
for its DECFILTER_MSR bit BSY to be 0 (zero) before disabling the input of the next block in the
sequence.
• Each block in a new cascade combo must be configured with its input disabled. When the mode
configuration is done, the combo blocks must have their inputs enabled in order, from the Tail
towards the Head block.
• A single block must also be reconfigured the same way, to or from a cascade combo configuration:
first disabling its input, and then waiting for a non-busy state before writing DECFILTER_MCR
field CASCD.
To take cascade combo blocks to or from freeze or low power modes, a similar procedure must be used:
• Take the Head to freeze or low-power first, wait for DECFILTER_MSR bit BSY = 0, and repeat
the procedure for the other blocks in the chain in sequence, towards the Tail block.
• Take the blocks out of freeze or low-power modes in the inverse sequence, from Tail to Head.
single
Head
Middle Tail
single
Head Tail single
(arrows show just the physical cascading order)
Head Tail
Head Tail single single Head Tail
single Head
Middle Middle Middle Tail single single
Tail single
Head Middle Tail
single
Head Middle