Texas Instruments TMS320C645x DSP manual Ewint, Tcnt

Models: TMS320C645x DSP

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EMAC Control Module Registers

3.3EMAC Control Module Interrupt Timer Count Register (EWINTTCNT)

The EMAC control module interrupt timer count register (EWINTTCNT) is used to control the generation of back-to-back interrupts from the EMAC and MDIO modules. The value of this timer count is loaded into an internal counter every time interrupts are enabled using EWCTL. A second interrupt cannot be generated until this count reaches 0. The counter is decremented at a frequency of CPU clock/6; its default reset count is 0 (inactive), its maximum value is 1 FFFFh (131 071).

The EMAC control module interrupt timer count register (EWINTTCNT) is shown in Figure 15 and described in Table 13.

Figure 15. EMAC Control Module Interrupt Timer Count Register (EWINTTCNT)

31

17

16

Reserved

 

EWINT

 

 

TCNT

R-0

 

R/W-0

15

 

0

EWINTTCNT

 

 

R/W-0

LEGEND: R = Read only; R/W = Read/Write; -n= value after reset

Table 13. EMAC Control Module Interrupt Timer Count Register (EWINTTCNT) Field Descriptions

Bit

Field

Value

Description

31-17

Reserved

0

Reserved

16-0

EWINTTCNT

 

Interrupt timer count. EWINTTCNT is a 17-bit interrupt timer count that is used to control the

 

 

 

generation of back-to-back interrupts from the EMAC and MDIO modules. The value of

 

 

 

EWINTTCNT is loaded in an internal time counter every time interrupts are enabled using EWCTL

 

 

 

register by writing a '1'to INTEN bit. (Note the INTEN bit must transition from '0'to '1'to initialize

 

 

 

the internal time counter.) Once initialized, the time counter will count down with each peripheral

 

 

 

clock till it reaches zero. A second interrupt cannot be generated until this counter reaches 0. Any

 

 

 

time the time counter has a non-zero value, the interrupt logic will block the EMAC_MDIO_INT

 

 

 

interrupt to the CPU. Thus, if any of the interrupts coming to the EMAC control module is asserted,

 

 

 

the interrupt logic will assert the EMAC_MDIO_INT signal to the CPU, provided the INTEN bit in the

 

 

 

EWCTL register is set, and the time counter value is zero.

SPRU975B –August 2006

Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)

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Texas Instruments TMS320C645x DSP manual Ewint, Tcnt