4.3.4. Oscillator Registers, SYS_OSCx

The oscillator registers, SYS_OSC0 through to SYS_OSC7 are read/write lockable registers that control the frequency of the clocks generated by the ICS307 programmable oscillators OSC0 through to OSC7.

Table 4.7 lists the SYS_OSCx registers address locations.

Table 4.7. SYS_OSCx registers

Register

Address

Access

Description

SYS_OSC0

0x1000000C

Read/Write LockableSets OSC0 clock frequency

SYS_OSC1

0x10000010

Read/Write LockableSets OSC1 clock frequency

SYS_OSC2

0x10000014

Read/Write LockableSets OSC2 clock frequency

SYS_OSC3

0x10000018

Read/Write LockableSets OSC3 clock frequency
SYS_OSC4

0x1000001C

Read/Write LockableSets OSC4 clock frequency
SYS_OSC50x100000D4Read/Write LockableSets OSC5 clock frequency
SYS_OSC60x100000D8Read/Write LockableSets OSC6 clock frequency
SYS_OSC70x100000ECRead/Write LockableSets OSC7 clock frequency

Figure 4.5 shows the registers bit assignment.

Note

The values written take effect after the next soft reset (nSYSRST).

Figure 4.5. SYS_OSCx register

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The function of the register bits are shown in Table 4.8. For more detail on bit values, see ICS307 programmable clock generators and Clock frequency restrictions.

Table 4.8. SYS_OSCx register bit assignments

Bits

Access

NameReset

Description

[31:20]

Write ignored, read as zero0x000Undefined
[19]Write ignored, read as zerob0Undefined

[18:16]

Read/Write

DIVIDE[2:0]bxxxOutput divider select

[15:9]

Read/Write

RDW[6:0]bxxxxxxxReference divider value

[8:0]

Read/Write

VDW[8:0]bxxxxxxxxxVCO divider value

Note

Before you can write to a SYS_OSCx register, you must unlock it by writing the value 0x0000A05F to the SYS_LOCK register. After writing to the SYS_OSCx register, you should relock it by writing any value other than 0x0000A05F to the SYS_LOCK register.

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