ST10R272L - INTERRUPT AND TRAP FUNCTIONS
92/320
Byte/Word Transfer bit BWT controls whether a byte or a word is moved during a PEC
service cycle. This selection controls the transferred data size and the increment step for the
modified pointer.
Increment Control Field INC specifies whether one of the PEC pointers is incremented
after the PEC transfer. It is not possible to increment both pointers. If the pointers are not
modified (INC=00), the channel will always move data from the same source to the same
destination.
Note
The reserved combination 11 is changed to 10 by hardware. However, it is not
recommended to use this combination.
The PEC Transfer Count Field COUNT controls the action of a PEC channel. The content
of bit field COUNT at the time the request is activated, specifies the action. COUNT may
specify a number of PEC transfers, unlimited transfers or no PEC service at all.
The table below summarizes how the COUNT field, the interrupt requests flag IR and the
PEC channel action depend on the previous content of COUNT.
The PEC transfer counter makes it possible to service a specified number of requests by the
respective PEC channel, and then (when COUNT reaches 00h) activate the interrupt service
routine associated with the priority level. After each PEC transfer, the COUNT field is
decremented and the request flag is cleared to indicate that the request has been serviced.
Register
Address
Reg. Space
Register
Address
Reg. Space
PECC0
FEC0h / 60h
SFR
PECC4
FEC8h / 64h
SFR
PECC1
FEC2h / 61h
SFR
PECC5
FECAh / 65h
SFR
PECC2
FEC4h / 62h
SFR
PECC6
FECCh / 66h
SFR
PECC3
FEC6h / 63h
SFR
PECC7
FECEh / 67h
SFR
Table 15 PEC control register addresses
COUNT
COUNT
1
IR after PEC
service
Action of PEC Channel and Comments
FFh FFh ‘0’
Move a Byte / Word
Continuous transfer mode, i.e. COUNT is not modified
FEh..02h
FDh..01h
‘0’
Move a Byte / Word and decrement COUNT
Table 16 Dependency on COUNT of the count field, IR and PEC channel