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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
731 of 808
NXP Semiconductors
UM10360
Chapter 34: Appendix: Cortex-M3 User Guide
The CMSIS provides thread-safe code that gives atomic access to the Interrupt Priority
Registers. For more information see the description of the
NVIC_SetPriority
function in
Section 34–4.2.10.1 “NVIC programming hints”
shows how the interrupts,
or IRQ numbers, map onto the interrupt registers and corresponding CMSIS variables that
have one bit per interrupt.
[1]
Each array element corresponds to a single NVIC register, for example the element
ICER[1]
corresponds to the ICER1 register.
4.2.2 Interrupt Set-enable Registers
The ISER0-ISER3 registers enable interrupts, and show which interrupts are enabled.
See:
•
the register summary in
for the register attributes
•
for which interrupts are controlled by each register.
The bit assignments are shown in
.
If a pending interrupt is enabled, the NVIC activates the interrupt based on its priority. If an
interrupt is not enabled, asserting its interrupt signal changes the interrupt state to
pending, but the NVIC never activates the interrupt, regardless of its priority.
4.2.3 Interrupt Clear-enable Registers
The ICER0-ICER3 registers disable interrupts, and show which interrupts are enabled.
See:
•
the register summary in
for the register attributes
•
for which interrupts are controlled by each register.
The bit assignments are shown in
.
Table 617. Mapping of interrupts to the interrupt variables
Interrupts
CMSIS array elements
Set-enable
Clear-enable
Set-pending
Clear-pending
Active Bit
0-31
ISER[0]
ICER[0]
ISPR[0]
ICPR[0]
IABR[0]
32-63
ISER[1]
ICER[1]
ISPR[1]
ICPR[1]
IABR[1]
64-95
ISER[2]
ICER[2]
ISPR[2]
ICPR[2]
IABR[2]
96-127
ISER[3]
ICER[3]
ISPR[3]
ICPR[3]
IABR[3]
Table 618. ISER bit assignments
Bits
Name
Function
[31:0]
SETENA
Interrupt set-enable bits.
Write:
0 = no effect
1 = enable interrupt.
Read:
0 = interrupt disabled
1 = interrupt enabled.