Oki MSM66591, User Manual

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17-1
MSM66591/ML66592 User's Manual
Chapter 17 Transition Detector Functions
17
Table 17-1 Transition Detector Control SFRs
16
R/W 016E
TRNS Control Register TRNSCON 0000
016F
004F Transition Detector — 00
[Note] Addresses above are not consecutive.
8
—
—
TRNSIT
Address [H] Name
Abbreviated
Name (BYTE)
R/W
8/16-Bit
Operation
Reset
State [H]
Abbreviated
Name (WORD)
17.1 Transition Detector Control Register (TRNSCON)
TRNSCON is an 16-bit register that specifies the valid edges for TRNS0–TRNS7 pins.
Since only 16-bit data is accessible to TRNSCON, bit manipulation instructions such as
SB and RB can not be executed.
At reset (when the
RES
signal is input, the BRK instruction is executed, the watchdog
timer is overflown, or an operation code trap is generated), TRNSCON becomes
0000H, and the falling edge is specified as the valid edge.
Figure 17-1 shows the configuration of TRNSCON (low-order bits), and Figure 17-2
shows the configuration of TRNSCON (high-order bits).
17. Transition Detector Functions
The MSM66591/ML66592 have eight transition detector functions, which detect the
valid edges (rise, fall, both edges) of an input pin.
If the valid edge specified by TRNSCON is input to TRNS0–TRNS7 pins, the corre-
sponding bit 0 to bit 7 of the transition detector (TRNSIT) is set to "1". Reset the bit of
TRNSIT to "0" by the program.
TRNS0–TRNS7 pins are assigned as secondary functions of P4_0–P4_7 of Port 4.
Therefore the corresponding bit of the Port 4 secondary function control register must
be set to "1" to access the transition detector function.
At reset (when the
RES
signal is input, the BRK instruction is executed, the watchdog
timer is overflown, or an operation code trap is generated), TRNSIT becomes 00H.
If the secondary function of Port 4 is selected, TRNSIT may become undefined, de-
pending on the status of TRNS0–TRNS7 pins. When using transition detector functions,
set the Port 4 secondary function control register to "1", and then reset the correspond-
ing bit of TRNSIT to "0".
Table 17-1 lists the transition detector control SFRs.