TMS320F2809, TMS320F2808, TMS320F2806

TMS320F2802, TMS320F2801, TMS320C2802

TMS320C2801, TMS320F28016, TMS320F28015

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SPRS230L –OCTOBER 2003 –REVISED DECEMBER 2009

Figure 6-10shows an example for the effect of writing into PLLCR register. In the first phase, PLLCR = 0x0004 and SYSCLKOUT = OSCCLK x 2. The PLLCR is then written with 0x0008. Right after the PLLCR register is written, the PLL lock-up phase begins. During this phase, SYSCLKOUT = OSCCLK/2. After the PLL lock-up is complete (which takes 131072 OSCCLK cycles), SYSCLKOUT reflects the new operating frequency, OSCCLK x 4.

OSCCLK

Write to PLLCR

SYSCLKOUT

OSCCLK * 2

OSCCLK/2

OSCCLK * 4

(Current CPU

(CPU Frequency While PLL is Stabilizing

(Changed CPU Frequency)

Frequency)

With the Desired Frequency. This Period

 

 

(PLL Lock-up Time, tp) is

 

 

131072 OSCCLK Cycles Long.)

 

Figure 6-10. Example of Effect of Writing Into PLLCR Register

6.9General-Purpose Input/Output (GPIO)

6.9.1GPIO - Output Timing

Table 6-14. General-Purpose Output Switching Characteristics

 

 

PARAMETER

 

 

 

 

 

 

MIN

MAX

UNIT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tr(GPO)

Rise time, GPIO switching low to high

All GPIOs

 

 

 

 

 

 

8

 

ns

tf(GPO)

Fall time, GPIO switching high to low

All GPIOs

 

 

 

 

 

 

8

 

ns

tfGPO

Toggling frequency, GPO pins

 

 

 

 

 

 

 

25

 

MHz

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GPIO

tr(GPO)

tf(GPO)

Figure 6-11. General-Purpose Output Timing

Copyright © 2003–2009, Texas Instruments Incorporated

Electrical Specifications

109

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Texas Instruments TMS320F2808 General-Purpose Input/Output Gpio, Gpio Output Timing, Sysclkout Oscclk OSCCLK/2