Texas Instruments TMS320DM646X DMSOC specs

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Table 3. Description of the Asynchronous Configuration Register (ACFGn) (continued)

Parameter	Description
ASIZE	Asynchronous Device Bus Width.
	This field determines the data bus width of the asynchronous interface in the following way:
	• ASIZE = 0 selects an 8-bit bus
	• ASIZE = 1 selects a 16-bit bus
	The configuration of ASIZE determines the function of the EM_A and EM_BA pins as described in
	Section 2.5.1. This field also determines the number of external accesses required to fulfill a request
	generated by one of the sources mentioned in Section 2.2. For example, a request for a 32-bit word
	would require four external access when ASIZE = 0h. Refer to the datasheet of the external
	asynchronous device to determine the appropriate setting for this field.

Table 4. Description of the Asynchronous Wait Cycle Configuration Register (AWCCR)

Parameter	Description
WPn	WAIT Polarity.
	• WPn = 0 selects active-low polarity
	• WPn = 1 selects active-high polarity
	When set to 1, the EMIF will wait if the EM_WAITn pin is high. When cleared to 0, the EMIF will wait if the
	EM_WAITn pin is low. The EMIF must have the Extended Wait mode enabled (EW bit in the asynchronous
	configuration register (ACFGn) is set to 1) for the EM_WAITn pin to affect the width of the strobe period.

MEWC	Maximum Extended Wait Cycles.
	This field configures the number of EMIF clock cycles the EMIF will wait for the EM_WAITn pin to be deactivated
	during the strobe period of an access cycle. The maximum number of EMIF clock cycles the EMIF will wait is
	determined by the following formula:
	Maximum Extended Wait Cycles = (MEWC + 1) × 16
	If the EM_WAITn pin is not deactivated within the time specified by this field, the EMIF resumes the access cycle,
	registering whatever data is on the bus and preceding to the hold period of the access cycle. This situation is
	referred to as an asynchronous timeout. An asynchronous timeout generates an interrupt if it has been enabled in
	the EMIF interrupt mask set register (EIMSR). Refer to Section 2.5.11 for more information about the EMIF
	interrupts.

Table 5. Description of the EMIF Interrupt Mask Set Register (EIMSR)

Parameter Description

WRMSETn Wait Rise Mask Set.

Writing a 1 enables an interrupt to be generated when a rising edge on EM_WAITn occurs.

Writing a 1 to this bit enables an interrupt to be generated when an asynchronous timeout occurs.

Writing a 1 to this bit disables the interrupt, clearing the WRMSETn bit in the EMIF interrupt mask set register (EIMSR).

Writing a 1 to this bit disables the interrupt, clearing the ATMSET bit in the EMIF interrupt mask set register (EIMSR).

SPRUEQ7C –February 2010	Asynchronous External Memory Interface (EMIF) 13
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