UM10462
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User manual
Rev. 5.5 — 21 December 2016
23 of 523
NXP Semiconductors
UM10462
Chapter 3: LPC11U3x/2x/1x System control block
3.5.2 Peripheral reset control register
This register allows software to reset specific peripherals. A 0 in an assigned bit in this
register resets the specified peripheral. A 1 negates the reset and allows peripheral
operation.
Remark:
Before accessing the SSP and I2C peripherals, write a 1 to this register to
ensure that the reset signals to the SSP and I2C are de-asserted.
3.5.3 System PLL control register
This register connects and enables the system PLL and configures the PLL multiplier and
divider values. The PLL accepts an input frequency from 10 MHz to 25 MHz from various
clock sources. The input frequency is multiplied to a higher frequency and then divided
down to provide the actual clock used by the CPU, peripherals, and memories. The PLL
can produce a clock up to the maximum allowed for the CPU.
Table 7.
System memory remap register (SYSMEMREMAP, address 0x4004 8000) bit
description
Bit
Symbol
Value
Description
Reset
value
1:0
MAP
System memory remap. Value 0x3 is reserved.
0x2
0x0
Boot Loader Mode. Interrupt vectors are re-mapped to Boot
ROM.
0x1
User RAM Mode. Interrupt vectors are re-mapped to Static
RAM.
0x2
User Flash Mode. Interrupt vectors are not re-mapped and
reside in Flash.
31:2
-
-
Reserved
-
Table 8.
Peripheral reset control register (PRESETCTRL, address 0x4004 8004) bit
description
Bit
Symbol
Value
Description
Reset
value
0
SSP0_RST_N
SSP0 reset control
0
0
Resets the SSP0 peripheral.
1
SSP0 reset de-asserted.
1
I2C_RST_N
I2C reset control
0
0
Resets the I2C peripheral.
1
I2C reset de-asserted.
2
SSP1_RST_N
SSP1 reset control
0
0
Resets the SSP1 peripheral.
1
SSP1 reset de-asserted.
3
-
Reserved
-
31:4
-
-
Reserved
-