TMS320C6678
Multicore Fixed and Floating-Point Digital Signal Processor
SPRS691D—April 2013
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2.5.4 PLL Boot Configuration Settings
The PLL default settings are determined by the BOOTMODE[12:10] bits. The table below shows settings for various
input clock frequencies.
Table 2-24
C66x DSP System PLL Configuration (1)
800 MHz Device
1000 MHz Device
1200 MHz Device
1250 MHz Device
PASS PLL = 350 MHz (2)
BOOTMODE Input Clock
[12:10]
0b000
0b001
0b010
0b011
0b100
0b101
0b110
0b111
Freq (MHz)
50.00
0
0
0
0
31
23
19
15
800
0
0
0
0
4
0
4
39
29
24
19
63
7
1000
1000.05
1000
1000
1000
1000
1000
0
0
0
0
47
35
29
23
1200
0
1
3
0
0
0
0
2
49
74
1250
0
41
1050
66.67
800.04
800
1200.06
1200
1250.06
1
62
1050.053
1050
80.00
124 1250
3
104
20
100.00
156.25
250.00
312.50
122.88
800
1200
24
15
9
1250
1250
1250
1250
0
1050
24 255 800
31 800
24 383 1200
47 1200
24 191 1200
24
4
335
41
1050
4
4
1050
24 127 800
47 624 800
31
7
24
167
204
1050
28 471 999.989 31 624 1200
60
1249.28 11
1049.6
End of Table 2-24
1 The PLL boot configuration of initial silicon 1.0 may only support 800MHz, 1000MHz and 1200MHz frequencies by default.
2 The PASS PLL generates 1050 MHz and is internally divided by 3 to feed 350 MHz to the packet accelerator.
OUTPUT_DIVIDE is the value of the field of SECCTL[22:19]. This will set the PLL to the maximum clock setting
for the device (with OUTPUT_DIVIDE=2, by default).
CLK = CLKIN × ((PLLM+1) ÷ (OUTPUT_DIVIDE × (PLLD+1)))
The configuration for the PASS PLL is also shown. The PASS PLL is configured with these values only if the Ethernet
boot mode is selected with the input clock set to match the main PLL clock (not the PASS clock). See Table 2-4 for
details on configuring Ethernet boot mode. The output from the PASS PLL goes through an on-chip divider to
reduce the operating frequency before reaching the NETCP. The PASS PLL generates 1050 MHz, and after the chip
divider (=3), feeds 350 MHz to the NETCP.
The Main PLL is controlled using a PLL controller and a chip-level MMR. The DDR3 PLL and PASS PLL are
controlled by chip level MMRs. For details on how to set up the PLL see section 7.5 ‘‘Main PLL and PLL Controller’’
on page 139. For details on the operation of the PLL controller module, see the Phase Locked Loop (PLL) for KeyStone
Devices User Guide in ‘‘Related Documentation from Texas Instruments’’ on page 73.
2.6 Second-Level Bootloaders
Any of the boot modes can be used to download a second-level bootloader. A second-level bootloader allows for any
level of customization to current boot methods as well as the definition of a completely customized boot.
Copyright 2013 Texas Instruments Incorporated
Device Overview 41
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