ARM ARM DUI 0224I manual Oscillator registers, SYSOSCx, Shows the bit assignment of the registers

Programmer’s Reference

4.3.4Oscillator registers, SYS_OSCx

The oscillator registers, SYS_OSC0 to SYS_OSC4, at 0x1000000C–0x1000001Care read/write registers that control the frequency of the clocks generated by the ICS307 programmable oscillators. A serial interface transfers the values in the registers to the programmable oscillators when a reset occurs.

Note

If the DEV CHIP RECONFIG pushbutton is pressed, the contents of the

SYS_OSCRESETx registers are copied into the SYS_OSCx registers before the contents are transmitted to the programmable oscillators. This allows the clock frequencies and the clock divider ratios to be changed at the same time.

Figure 4-8 shows the bit assignment of the registers.

Figure 4-8 Oscillator Register, SYS_OSCx

Table 4-6 lists the details of the SYS_OSCx registers. For more detail on bit values, see ICS307 programmable clock generators on page 3-48 and Clock rate restrictions on page B-5.

Table 4-6 Oscillator Register, SYS_OSCx bit assignment

Bits	Access	Description
[31:19]	Reserved, Use read-modify-write to preserve value.
[18:16]	Read/write	DIVIDE[2:0], output divider select
[15:9]	Read/write	RDW[6:0], reference divider word
[8:0]	Read/write	VDW[8:0], VCO divider word

Note

Before writing to a SYS_OSC register, unlock it by writing the value 0x0000A05F to the SYS_LOCK register. After writing the SYS_OSC register, relock it by writing any value other than 0x0000A05F to the SYS_LOCK register.

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