Texas Instruments TMS320F2837 D Series Workshop Guide And Lab Manual

Oscillator/PLL Clock Module
5 - 4 TMS320F2837xD Microcontroller Workshop - System Initialization
F28x7x PLL and LOSPCP
IMULT CLKIN
0 0 0 0 0 0 0 OSCCLK / n * (PLL bypass)
0 0 0 0 0 0 1 OSCCLK x 1 / n
0 0 0 0 0 1 0 OSCCLK x 2 / n
0 0 0 0 0 1 1 OSCCLK x 3 / n
1 1 1 1 1 0 1 OSCCLK x 125/ n
1 1 1 1 1 1 0 OSCCLK x 126 / n
1 1 1 1 1 1 1 OSCCLK x 127 / n
PLL
PLLCLK
OSCCLK
CPUx
PLLSYSCLK
CPUx.SYSCLK
LOSPCP
(PLL bypass)
CPUx.LSPCLK
MUX
1/n
ClkCfgRegs.SYSPLLMULT.bit.IMULT
ClkCfgRegs.SYSCLKDIVSEL.bit.PLLSYSCLKDIV
ClkCfgRegs.LOSPCP.bit.LSPCLK
LSPCLK Peripheral Clk Freq
0 0 0 CPUx.SYSCLK / 1
0 0 1 CPUx.SYSCLK / 2
0 1 0 CPUx.SYSCLK / 4 *
0 1 1 CPUx.SYSCLK / 6
1 0 0 CPUx.SYSCLK / 8
1 0 1 CPUx.SYSCLK / 10
1 1 0 CPUx.SYSCLK / 12
1 1 1 CPUx.SYSCLK / 14
LSBs in reg. – others reserved
* default
SYSPLL
DIVSEL n
111111 /126
000010 /4 *
000001 /2
000000 /1
• • •
• • •
FMULT CLKIN
0 0 Fractional x 0 *
0 1 Fractional x 0.25
1 0 Fractional x 0.5
1 1 Fractional x 0.75
• • •
• • •
ClkCfgRegs.SYSPLLMULT.bit.FMULT
0*
1
ClkCfgRegs.SYSPLLCTL1.bit.PLLCLKEN
The clock sources can be multiplied using the PLL and divided down to produce the desired clock
frequencies for a specific application. By default, the CPU1 subsystem owns the PLL clock
configuration, however a clock control semaphore is available for the CPU2 subsystem to access
the clock configuration registers.
A clock source can be fed directly into the core or multiplied using the PLL. The PLL gives us the
capability to use the internal 10 MHz oscillator and run the device at the full clock frequency. If
the input clock is removed after the PLL is locked, the input clock failed detect circuitry will issue a
limp mode clock of 1 to 4 MHz. Additionally, an internal device reset will be issued. The low-
speed peripheral clock prescaler is used to clock some of the communication peripherals.
The PLL has a 7-bit integer and 2-bit fractional ratio control to select different CPU clock rates.
The C28x CPU provides a SYSCLK clock signal. This signal is prescaled to provide a clock
source for some of the on-chip communication peripherals through the low-speed peripheral clock
prescaler. Other peripherals are clocked by SYSCLK and use their own clock prescalers for
operation.

Texas Instruments TMS320F2837 D Series Specifications

General

Brand	Texas Instruments
Model	TMS320F2837 D Series
Category	Microcontrollers
Language	English