Intel 8XC196MD, 8XC196MH, 8XC196MC Explanation of AC Symbols, AC Timing Definitions, Conditions

INTERFACING WITH EXTERNAL MEMORY

15.6.1 Explanation of AC Symbols

Each symbol consists of two pairs of letters prefixed by “T” (for time). The characters in a pair indicate a signal and its condition, respectively. Symbols represent the time between the two sig- nal/condition points. For example, TLLRL is the time between signal L (ALE/ADV#) condition L (Low), and signal R (RD#) condition L (Low). Table 15-7 defines the signal and condition codes.

Table 15-7. AC Timing Symbol Definitions

Signals

A	Address	Q	Output Data
B	BHE#	R	RD#
C†	CLKOUT	W	WR#, WRH#, WRL#
D	Input Data	X	XTAL1
G	BUSWIDTH	Y	READY
L	ALE/ADV#

Conditions

H High

L Low

V Valid

XNo Longer Valid

Z Floating

†The CLKOUT pin is available only on the 8XC196MC, MD microcontrollers.

15.6.2AC Timing Definitions

Tables 15-8 and 15-9 define the AC timing specifications that the memory system must meet and those that the microcontroller will provide.

Table 15-8. External Memory Systems Must Meet These Specifications

Symbol	Definition
TAVDV	Address Valid to Input Data Valid
	Maximum time the memory system has to output valid data after the microcontroller outputs a
	valid address.
TRHDZ	RD# High to Input Data Float
	Time after the microcontroller deasserts RD# until the memory system must float the bus. If this
	timing is not met, bus contention will occur.
TRLDV	RD# Low to Input Data Valid
	Maximum time the memory system has to output valid data after the microcontroller asserts
	RD#.

†The CLKOUT pin is available only on the 8XC196MC, MD microcontrollers.

15-33