UM10850
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User manual
Rev. 2.4 — 13 September 2016
60 of 464
NXP Semiconductors
UM10850
Chapter 4: LPC5410x System configuration (SYSCON)
4.5.47 Dual-CPU related registers
These registers control usage aspects of the two CPUs in an LPC54102 device. They are
not used in an LPC54101 device that only provide a single CPU.
4.5.47.1 CPU Control register
The CPUCTRL register provides control for the 2 CPUs. Note that the Cortex-M4 is
factory set to be the master. The user can assign Cortex-M0+ to be the master CPU via
this register if needed after it is brought out of reset by Cortex-M4. The master CPU
cannot be reset or have its clock disabled via this register. Only the master CPU can use
the Power APIs to cause the device to enter reduced power modes.
If the clock to the slave CPU is to be disabled at some point in the application for power
savings, that CPU should have entered its own sleep mode prior to that point. This avoids
incomplete operations in the slave CPU.
Table 81.
CPU Control register (CPUCTRL, address 0x4000 0300) bit description
Bit
Symbol
Value
Description
Reset
value
0
MASTERCPU
Indicates which CPU is considered the master. This is factory set assign the
Cortex-M4 as the master.
The master CPU cannot have its clock turned off via the related CMnCLKEN bit or
be reset via the related CMxRSTEN in this register.
The slave CPU wakes up briefly following device reset, then goes back to sleep
until activated by the master CPU.
1
0
M0+. Cortex-M0+ is the master CPU.
1
M4. Cortex-M4 is the master CPU.
1
-
-
Reserved. Read value is undefined, only zero should be written.
-
2
CM4CLKEN
Cortex-M4 clock enable.
1
0
Disabled. The Cortex-M4 clock is not enabled.
1
Enabled. The Cortex-M4 clock is enabled.
3
CM0CLKEN
Cortex-M0+ clock enable.
1
0
Disabled. The Cortex-M0+ clock is not enabled.
1
Enabled. The Cortex-M0+ clock is enabled.
4
CM4RSTEN
Cortex-M4 reset.
0
0
Disabled. The Cortex-M4 is not being reset.
1
Enabled. The Cortex-M4 is being reset.
5
CM0RSTEN
Cortex-M0+ reset.
0
0
Disabled. The Cortex-M0+ is not being reset.
1
Enabled. The Cortex-M0+ is being reset.
6
POWERCPU
Identifies the owner of reduced power mode control: which CPU can cause the
device to enter Deep Sleep, Power-down, and Deep Power-down modes.
1
0
M0+. Cortex-M0+ is the owner of reduced power mode control.
1
M4. Cortex-M4 is the owner of reduced power mode control.
14:7
-
-
Reserved. Read value is undefined, only zero should be written.
-
15
-
-
Must be written as a 1.
-
31:16
-
-
Must be written as 0xC0C4 for the write to have an effect.
-