Table 10: 68-lead Flat Pack Pin Descriptions
QFP Pin#
I/O
Name
Active
Description
41
TUO
BHE
Low
Byte High Enable. The assertion of the BHE signal will occur
for all 16-bit word writes, and high byte writes in both 8- and 16-
bit wide bus cycles.
Setting CCR.2 = 1 enables the BHEfunction of pin 41.
TUO
WRH
Low
Write High. The WRH signal is asserted for high byte writes,
and word writes for 16-bit wide bus cycles. Additionally, WRH
is asserted for all write operations when using an 8-bit wide bus
cycle.
Setting CCR.2 = 0 enables the WRH function of pin 41.
42
43
TI
TI
P2.4
---
Port 2 Pin 4. An input only port pin that is read at location 10h
of HWindow 0.
T2RST
High
Timer 2 Reset. Asserting the T2RST signal will reset Timer 2.
To enable the T2RST function of pin 42, set IOC0.3 = 1 and
IOC0.5 = 0.
TI
READY
High
READY input. The READY signal is used to lengthen memory
cycles by inserting “wait states” for interfacing to slow peripher-
als. When the READY signal is high, no “wait states” are gener-
ated, and the CPU operation continues in a normal fashion. If
READY is low during the falling edge of CLKOUT, the mem-
ory controller inserts “wait states” into the memory cycle. “Wait
state” generation will continue until a falling edge of CLKOUT
detects READY as logically high, or until the number of “wait
states” is equal to the number programmed into CCR.4 and
CCR.5.
Note: The READY signal is only used for external memory
accesses, and is functional during the CCR fetch.
44
TI
TI
P2.3
---
---
Port 2 Pin 3. An input only port pin that is read at location 10h
of HWindow 0.
T2CLK
Timer 2 Clock input. Setting IOC0.7 = 0 and IOC3.0 = 0
enables this pin as the external clock source for Timer 2.
IOC0.7:
X
0
IOC3.0:
Timer 2 Clock Source:
Internal Clock Source
P2.3 External Clock Source
HSI.1 External Clock Source
1
0
0
1
45
TUB
AD15
---
Bit 15 of the Address/Data bus. This pin is a dedicated address
pin when operating with 8-bit wide bus cycles. For 16-bit wide
bus cycles, this pin is used as multiplexed address and data.
20
AEROFLEX [ AEROFLEX CIRCUIT TECHNOLOGY ]
