Infineon Technologies C166S V2 User Manual page 140

Field
BWT
COUNT
The Byte/Word Transfer bit (BWT) of the PECCx register determines if a byte or a word
is to be moved during a PEC service cycle and defines an increment step size for the
pointer(s) to be modified.
The PEC Transfer Count field (COUNT) of the PECCx directly controls the action of the
respective PEC channel. The contents of the bit field COUNT may specify a certain
number of PEC transfers, unlimited transfers, or no PEC service at all.
– If the PEC transfer counter COUNT value is set to 00
are processed instead of PEC data transfers and the corresponding PEC channel
remains idle.
– Continuous data transfers are selected by setting the bit field COUNT to FF
In this case, COUNT is not decremented by the transfers and the respective PEC
channel can serve unlimited number of PEC requests until it is modified by the
program.
– If the bit field COUNT is set to service a specified number of requests by the respective
PEC channel, it is decremented with each PEC transfer and the request flag is cleared
to indicate that the request has been serviced. When COUNT reaches 00
immediately activates the interrupt service routine that has the same priority level
(EOPINT = 0) or triggers the "End of PEC" interrupt with a different priority level
(EOPINT = 1). When COUNT is decremented from 01
the request flag will be cleared if EOPINT is set to 1. If EOPINT is 0, the request flag
will not be cleared and another interrupt request will be generated on the same priority
level. The respective PEC channel remains idle and the associated interrupt service
routine is activated instead of PEC transfer because COUNT contains the 00
(see Section 5.4.3).
The EOPIC register is the interrupt control register of the End Of PEC interrupt.
The Register PECISNC contains flags of the "End of PEC" interrupt node. This node is
used when enhanced "End of PEC" interrupt feature was invoked and control bit EOPINT
is set to 1 in the corresponding PECCx.
Figure 5-4 shows the usage of the "End of PEC" interrupt subnode:
User Manual
Bits Type Description
[8] rw Byte/Word Transfer Selection
0
1
[7:0] rwh PEC Transfer Count
Counts PEC transfers and influences the
channel´s action (see section below)
Interrupt and Exception Handling
Transfer a word
Transfer a byte
, the normal interrupt requests
H
H
5-140
User Manual
C166S V2
to 00 after a data transfer,
H
V 1.7, 2001-01
value.
H
, it
H
value.
H