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On-Chip Clock Synthesis

Table 10-3. CLKOUT Pin Control (Continued)

TSTEN

CS[1:0]

CS0

CLKO

 

 

 

 

 

 

 

 

0

1

1

Disabled

 

 

 

 

1

0

0

(Reserved)

 

 

 

 

1

0

1

(Reserved)

 

 

 

 

1

1

0

(Reserved)

 

 

 

 

1

1

1

Prescaler output

 

 

 

 

10.2.1.8 Reserved Bits—Bits 5–4

Bits 5–4 are reserved and are read as zero during read operations. These bits should be written with zero to ensure future compatibility.

10.2.1.9 VCO Curve Select (VCS0)—Bit 3

The VCO curve select 0 (VCS0) control bit optimizes the VCO for the desired frequency range to provide better lock time and stability, as shown in Table 10-4. The VCS0 bit is cleared on DSP reset.

Table 10-4.

VCS0 Programming

 

 

VCS0

 

PLL Output Frequency

 

 

 

 

 

 

0

 

40 MHz to 70 MHz

 

 

 

1

 

10 MHz to 40 MHz

 

 

 

10.2.1.10 Reserved Bits—Bits 2–0

Bits 2–0 are reserved and are read as zero during read operations. These bits should be written with zero to ensure future compatibility.

10.2.2 PLL Control Register 0 (PCR0)

The PLL control register 0 (PCR0) is a 16-bit read/write register used to direct the operation of the on-chip clock synthesis. The PCR0 controls the frequency programming of the PLL. The PCR0 control bits are defined in Section 10.2.2.1, “Reserved Bit—Bit 15,” through Section 10.2.2.3, “Reserved Bits—Bits 4–0.” All bits of PCR0 are cleared by DSP hardware reset.

10.2.2.1 Reserved Bit—Bit 15

Bit 15 is reserved and is read as zero during read operations. This bit should be written with zero to ensure future compatibility.

10-8

DSP56824 User’s Manual

 

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