COP8782C Datasheet, PDF (9/28 Pages) National Semiconductor (TI) – 8-Bit One-Time Programmable (OTP) Microcontroller

Functional Description (Continued)
FIGURE 8 MICROWIRE PLUS Application
TL DD 11299 – 11
bit in the CNTRL register enables the SO and SK functions
on the G Port The SK pin must be selected as an input and
the SO pin selected as an output pin by appropriately setting
up the Port G configuration register Table V summarizes
the settings required to enter the Slave mode of operation
The user must set the BUSY flag immediately upon entering
the Slave mode This will ensure that all data bits sent by
the Master will be shifted properly After eight clock pulses
the BUSY flag will be cleared and the sequence may be
repeated (Figure 8)
TABLE V
G4
G5
G4
Config Config
Fun
Bit
Bit
G5 G6
Fun Fun
Operation
1
1
SO
Int SK SI MICROWIRE Master
0
1 TRI-STATE Int SK SI MICROWIRE Master
1
0
SO
Ext SK SI MICROWIRE Slave
0
0 TRI-STATE Ext SK SI MICROWIRE Slave
TIMER COUNTER
The device has a powerful 16-bit timer with an associated
16-bit register enabling it to perform extensive timer func-
tions The timer T1 and its register R1 are each organized
as two 8-bit read write registers Control bits in the register
CNTRL allow the timer to be started and stopped under
software control The timer-register pair can be operated in
one of three possible modes Table VI details various timer
operating modes and their requisite control settings
MODE 1 TIMER WITH AUTO-LOAD REGISTER
In this mode of operation the timer T1 counts down at the
instruction cycle rate Upon underflow the value in the regis-
ter R1 gets automatically reloaded into the timer which con-
tinues to count down The timer underflow can be pro-
grammed to interrupt the microcontroller A bit in the control
register CNTRL enables the TIO (G3) pin to toggle upon
timer underflows This allows the generation of square-wave
outputs or pulse width modulated outputs under software
control (Figure 9)
MODE 2 EXTERNAL COUNTER
In this mode the timer T1 becomes a 16-bit external event
counter The counter counts down upon an edge on the TIO
pin Control bits in the register CNTRL program the counter
to decrement either on a positive edge or on a negative
edge Upon underflow the contents of the register R1 are
automatically copied into the counter The underflow can
also be programmed to generate an interrupt (Figure 9)
MODE 3 TIMER WITH CAPTURE REGISTER
Timer T1 can be used to precisely measure external fre-
quencies or events in this mode of operation The timer T1
counts down at the instruction cycle rate Upon the occur-
rence of a specified edge on the TIO pin the contents of the
timer T1 are copied into the register R1 Bits in the control
register CNTRL allow the trigger edge to be specified either
as a positive edge or as a negative edge In this mode the
user can elect to be interrupted on the specified trigger
edge (Figure 10)
CNTRL
Bits
765
000
001
010
011
100
101
110
111
TABLE VI Timer Operating Modes
Operation Mode
T Interrupt
External Counter w Auto-Load Reg
External Counter w Auto-Load Reg
Not Allowed
Not Allowed
Timer w Auto-Load Reg
Timer w Auto-Load Reg Toggle TIO Out
Timer w Capture Register
Timer w Capture Register
Timer Underflow
Timer Underflow
Not Allowed
Not Allowed
Timer Underflow
Timer Underflow
TIO Pos Edge
TIO Neg Edge
Timer
Counts
On
TIO Pos Edge
TIO Neg Edge
Not Allowed
Not Allowed
t_c
t_c
t_c
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9
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