1.3.1.2 Configuring the Low-Speed Peripheral Clock Prescaler (LOSPCP)
The low-speed peripheral clock prescale (LOSPCP) registers are used to configure the low-speed peripheral
clocks. See
Figure 1-18. Low-Speed Peripheral Clock Prescaler Register (LOSPCP)
15
3
2
0
Reserved
LSPCLK
R-0
R/W-010
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-19. Low-Speed Peripheral Clock Prescaler Register (LOSPCP) Field Descriptions
Bits
Field
Value
Description
15-3
Reserved
Reserved
2-0
LSPCLK
These bits configure the low-speed peripheral clock (LSPCLK) rate relative to SYSCLKOUT:
≠ 0, then LSPCLK = SYSCLKOUT/(LOSPCP x 2)
If LOSPCP = 0, then LSPCLK = SYSCLKOUT
000
Low speed clock = SYSCLKOUT/1
001
Low speed clock= SYSCLKOUT/2
010
Low speed clock= SYSCLKOUT/4 (reset default)
011
Low speed clock= SYSCLKOUT/6
100
Low speed clock= SYSCLKOUT/8
101
Low speed clock= SYSCLKOUT/10
110
Low speed clock= SYSCLKOUT/12
111
Low speed clock= SYSCLKOUT/14
(1)
This register is EALLOW protected. See
for more information.
(2)
LOSPCP in this equation denotes the value of bits 2:0 in the LOSPCP register.
1.3.2 OSC and PLL Block
The on-chip oscillators and phase-locked loop (PLL) block provide the clocking signals for the device, as well as
control for low-power mode (LPM) entry or exit.
1.3.2.1 Input Clock Options
The device has two internal oscillators (INTOSC1 and INTOSC2) that need no external components. It also has
an on-chip, PLL-based clock module.
shows the different options that are available to clock the
device. Following are the input clock options available:
•
INTOSC1 (Internal zero-pin Oscillator 1):
This is the on-chip internal oscillator 1. It can provide the clock for
the Watchdog block, CPU-core and CPU-Timer 2. This is the default clock source upon reset.
•
INTOSC2 (Internal zero-pin Oscillator 2):
This is the on-chip internal oscillator 2. It can provide the clock
for the Watchdog block, CPU-core and CPU-Timer 2. Both INTOSC1 and INTOSC2 can be independently
chosen for the Watchdog block, CPU-core, and CPU-Timer 2. If using INTOSC2 as a clock source, refer to
the Advisory
Oscillator: CPU clock switching to INTOSC2 may result in missing clock condition after reset
in
the device errata.
•
XTAL OSC (Crystal or Resonator):
The on-chip crystal oscillator enables the use of an external quartz
crystal or ceramic resonator. The crystal or resonator is connected to the X1/X2 pins.
•
XCLKIN (External clock source):
If the on-chip crystal oscillator is not used, this mode allows it to be
bypassed. The device clock is generated from an external clock source input on the XCLKIN pin. Note that
the XCLKIN is multiplexed with GPIO19 or GPIO38 pin. The XCLKIN input can be selected as GPIO19 or
GPIO38 via the XCLKINSEL bit in XCLK register. The CLKCTL[XCLKINOFF] bit disables this clock input
System Control and Interrupts
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
69
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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