UM10850
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User manual
Rev. 2.4 — 13 September 2016
400 of 464
NXP Semiconductors
UM10850
Chapter 27: LPC5410x Mailbox
27.6.4 M4 interrupt register
The IRQ1 register allows other CPUs to send interrupt requests to the Cortex-M4 CPU.
This is intended to allow communication between CPUs. For example, one CPU could be
handling certain peripherals and signalling another CPU when data is available Each bit
can represent a different situation. The use of this feature is entirely up to the user.
27.6.5 M4 interrupt set register
The IRQ0SET register is used to set bits in the IRQ0 register.
27.6.6 M4 interrupt clear register
The IRQ0SET register is used to clear bits in the IRQ0 register.
27.6.7 Mutual Exclusion register
This register provides an Inter-Processor Communication handshake. When read for any
reason, the current value will be returned and the bit will be cleared. The bit will be set
again following any write.
This can be used as a resource allocation handshake between 2 CPUs. Whenever a CPU
wishes to access a shared resource (possibly a resource allocation table in memory), it
reads the MUTEX register. If it sees a 1, it has control over the shared resource allocation.
When it has made any needed changes, it write to the register, causing it to become set
again, and making control of shared resource allocation available to another CPU. If a
CPU reads a 0, it must wait for the bit to read as a 1 before accessing the shared resource
allocation information.
Table 443. M4 interrupt (IRQ1, address 0x1C02 C010) bit description
Bit
Symbol
Description
Reset value
31:0
INTREQ
If any bit is set, an interrupt request is sent to the Cortex-M0+
interrupt controller.
0
Table 444. M4 interrupt set register (IRQ1SET, address 0x1C02 C014) bit description
Bit
Symbol
Description
Reset Value
31:0
INTREQ
SET
Writing 1 sets the corresponding bit in the IRQ1 register.
-
Table 445. M4 interrupt clear register (IRQ1CLR, address 0x1C02 C018) bit description
Bit
Symbol
Description
Reset Value
31:0
INTREQ
CLR
Writing 1 clears the corresponding bit in the IRQ1 register.
-
Table 446. Mutual Exclusion register (MUTEX, address 0x1C02 C0F8) bit description
Bit
Symbol
Description
Reset value
0
EX
Cleared when read, set when written. See usage description
above.
1
31:1
-
Reserved
-