CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
65
5. Interrupt Controller
This chapter presents the Interrupt Controller and its associated registers. The interrupt controller provides a mechanism for a
hardware resource in PSoC
®
devices, to change program execution to a new address without regard to the current task being
performed by the code being executed. For a complete table of the Interrupt Controller registers, refer to the
of the Core Registers” on page 36
. For a quick reference of all PSoC registers in address order, refer to the
.
5.1
Architectural Description
A block diagram of the PSoC Interrupt Controller is shown in
, illustrating the concepts of
and
.
Figure 5-1. Interrupt Controller Block Diagram
The sequence of events that occur during interrupt process-
ing is as follows.
1. An interrupt becomes active, either because (a) the
interrupt condition occurs (for example, a timer expires),
(b) a previously posted interrupt is enabled through an
update of an interrupt
register, or (c) an interrupt is
pending and GIE is set from ‘0’ to ‘1’ in the CPU Flag
register.
2. The current executing instruction finishes.
3. The internal interrupt routine executes, taking 13 cycles.
During this time, the following actions occur:
a. The PCH, PCL, and Flag register (CPU_F) are
pushed onto the stack (in that order).
b. The CPU_F register is then cleared. Because this
clears the GIE bit to 0, additional interrupts are tem-
porarily disabled.
c. The PCH (PC[15:8]) is cleared to zero.
d. The interrupt vector is read from the interrupt control-
ler and its value is placed into PCL (PC[7:0]). This
sets the program counter to point to the appropriate
address in the interrupt table (for example, 001Ch for
the GPIO interrupt).
M8C Core
Interrupt
Source
(Timer,
GPIO, etc.)
Interrupt Taken
or
Posted
Interrupt
Pending
Interrupt
GIE
Interrupt Vector
Mask Bit Setting
D
R
Q
1
Priority
Encoder
Interrupt
Request
...
INT_MSKx:n
INT_CLRx:n Write
CPU_F[0]
...
n
0
Summary of Contents for CY8C28 series
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