MPC563XM Reference Manual, Rev. 1
Freescale Semiconductor
1133
Preliminary—Subject to Change Without Notice
Figure 25-12. Output buffer Interface Block Diagram
25.5.4.1
Output Buffer Overrun
The output overrun occurs when the output buffer is holding a not read output data and one more data is
asked to be written on it. Refer to
Section 25.5.4, “Output Buffer Description,”
for details of the output
buffer.
When ISEL=0, the output overrun occurs when a new output result is sent to the output buffer but the
previous result was not read by the PSI master block. For prefill, the output overrun does not occur because
the output buffer is not updated. In bypass or filter disabled, this overrun does not occur because the input
buffer waits until the output buffer is empty to transfer the data to the output. And in filter mode, the
overrun can occur when the filter result is ready to be written into the output buffer with decimation
enabled, but the output buffer has a data not read by the master block.
When ISEL=1, an output overrun occurs if a new output is ready and the output data flag ODF is not
cleared. Therefore, an output overrun does not occur if the ODF flag is cleared but the output buffer is not
read. For prefill, the output overrun does not occur because the output buffer is not updated. For filter
operation mode, when the filtering result is ready, the value is immediately written into the output buffer
and the overrun can occur. And in bypass mode, the data written into the input buffer is immediately
written into the output buffer. Therefore, the overrun can occur if the ODF flat is asserted in that time.
25.5.5
Bypass Configuration Description
The Bypass is a block configuration mode that is obtained by setting the bit field FTYPE[1:0] of module
configuration register DECFILTER_MCR to 00. In this case, the input data is sent to the output with no
change (bypass). This behavior is independent of ISEL setting. In addition, it is not performed the flush
cycle and the BSY bit is not set. However, the input and output flags are set.
When ISEL=0, the sample data/ timestamp and tag value is sent back to the master block with no changes.
For ISEL=1, only the sample data is sent to the output buffer. Moreover, decimation does not occur in
bypass.
OUTBUFF reg
From timestamp storage reg
Control
From MAC
bypass path