LM3S2776 Datasheet, PDF (182/785 Pages) Texas Instruments – Stellaris® LM3S2776 Microcontroller

System Control
1. Bypass the PLL and system clock divider by setting the BYPASS bit and clearing the USESYS
bit in the RCC register. This configures the system to run off a “raw” clock source and allows
for the new PLL configuration to be validated before switching the system clock to the PLL.
2. Select the crystal value (XTAL) and oscillator source (OSCSRC), and clear the PWRDN bit in
RCC/RCC2. Setting the XTAL field automatically pulls valid PLL configuration data for the
appropriate crystal, and clearing the PWRDN bit powers and enables the PLL and its output.
3. Select the desired system divider (SYSDIV) in RCC/RCC2 and set the USESYS bit in RCC. The
SYSDIV field determines the system frequency for the microcontroller.
4. Wait for the PLL to lock by polling the PLLLRIS bit in the Raw Interrupt Status (RIS) register.
5. Enable use of the PLL by clearing the BYPASS bit in RCC/RCC2.
5.4 Register Map
Table 5-6 on page 182 lists the System Control registers, grouped by function. The offset listed is a
hexadecimal increment to the register's address, relative to the System Control base address of
0x400F.E000.
Note: Spaces in the System Control register space that are not used are reserved for future or
internal use. Software should not modify any reserved memory address.
Note: Additional Flash and ROM registers defined in the System Control register space are
described in the “Internal Memory” on page 258.
Table 5-6. System Control Register Map
Offset Name
Type
Reset
Description
0x000 DID0
0x004 DID1
0x008 DC0
0x010 DC1
0x014 DC2
0x018 DC3
0x01C DC4
0x020 DC5
0x024 DC6
0x028 DC7
0x030 PBORCTL
0x034 LDOPCTL
0x040 SRCR0
0x044 SRCR1
0x048 SRCR2
RO
-
Device Identification 0
RO
-
Device Identification 1
RO
0x00FF.003F Device Capabilities 0
RO
0x0111.33FF Device Capabilities 1
RO
0x0007.1011 Device Capabilities 2
RO
0x813F.803F Device Capabilities 3
RO
0x0000.301F Device Capabilities 4
RO
0x0730.00FF Device Capabilities 5
RO
0x0000.0000 Device Capabilities 6
RO
0x4000.0F00 Device Capabilities 7
R/W
0x0000.7FFD Brown-Out Reset Control
R/W
0x0000.0000 LDO Power Control
R/W
0x00000000 Software Reset Control 0
R/W
0x00000000 Software Reset Control 1
R/W
0x00000000 Software Reset Control 2
See
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November 17, 2011
Texas Instruments-Production Data