Oki MSM66591, User Manual

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6-6
MSM66591/ML66592 User's Manual
Chapter 6 Port Functions
6.1.3 Configuration of Type C
(P3_4–P3_7, P4_0–P4_7, P5_0–P5_7, P6_0–P6_7,
P7_2, P7_3, P9_0–P9_7, P10_5–P10_7, P11_0–P11_3)
Type C ports function as the output pins of secondary functions, or as input pins of
secondary functions according to the specification of the secondary function control
register (PmSFn).
However, P7_2 and P7_3 automatically switch to their secondary function when the
EA
pin is set to "L" level. Then, when external program memory is accessed, P7_3 func-
tions as an output pin (
PSEN
pin) for a strobe signal to be output for a read operation,
and P7_2 functions as an output pin (ALE pin) for a strobe signal used to externally
latch the low-order 8 bits of addresses that are output from P0.
Figure 6-3 shows the configuration of a Type C port.
Figure 6-3 Configuration of Type C
C
PmIOn
Secondary function control signals
C: secondary function control signal
I : secondary function input data
O: secondary function output data
Pm_n
m = 3
n = 4–7
m = 4, 5, 6, 9
n = 0–7
m = 7
n = 2, 3
m = 10
n = 5–7
m = 11
n = 0–3
Internal Bus
Pm_n
Read
Control
Out
Control
PmSFn
I or O Pmn in