National CP3BT26 - Manual (Page 210)

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CP3BT26
27.2 VTU REGISTERS
The VTU contains a total of 19 user accessible registers, as
listed in Table 81. All registers are word-wide and are initial-
ized to a known value upon reset. All software accesses to
the VTU registers must be word accesses.
27.2.1 Mode Control Register (MODE)
The MODE register is a word-wide read/write register which
controls the mode selection of all four timer subsystems.
The register is clear after reset.
TxRUN The Timer Run bit controls whether the corre-
sponding timer is stopped or running. If set,
the associated counter and clock prescaler is
started depending on the mode of operation.
Once set, the clock to the clock prescaler and
the counter are enabled and the counter will
increment each time the clock prescaler
counter value matches the value defined in
the associated clock prescaler field (CxPR-
SC).
0 – Timer stopped.
1 – Timer running.
TMODx The Timer System Operating Mode field en-
ables or disables the Timer Subsystem and
defines its operating mode.
00 – Low-Power Mode. All clocks to the
counter subsystem are stopped. The
counter is stopped regardless of the val-
ue of the TxRUN bits. Read operations
to the Timer Subsystem will return the
last value; software must not perform
any write operations to the Timer Sub-
system while it is disabled since those
will be ignored.
01 – Dual 8-bit PWM mode. Each 8-bit
counter may individually be started or
stopped via its associated TxRUN bit.
The TIOx pins will function as PWM out-
puts.
10 – 16-bit PWM mode. The two 8-bit
counters are concatenated to form a sin-
gle 16-bit counter. The counter may be
started or stopped with the lower of the
two TxRUN bits, i.e. T1RUN, T3RUN,
T5RUN, and T7RUN. The TIOx pins will
function as PWM outputs.
11 – Capture Mode. Both 8-bit counters are
concatenated and operate as a single
16-bit counter. The counter may be start-
ed or stopped with the lower of the two
TxRUN bits, i.e., T1RUN, T3RUN,
T5RUN, and T7RUN. The TIOx pins will
function as capture inputs.
Table 81 VTU Registers
Name Address Description
MODE FF FF80h Mode Control Register
IO1CTL FF FF82h I/O Control Register 1
IO2CTL FF FF84h I/O Control Register 2
INTCTL FF FF86h
Interrupt Control
Register
INTPND FF FF88h
Interrupt Pending
Register
CLK1PS FF FF8Ah
Clock Prescaler
Register 1
CLK2PS FF FF98h
Clock Prescaler
Register 2
COUNT1 FF FF8Ch Counter 1 Register
PERCAP1 FF FF8Eh
Period/Capture 1
Register
DTYCAP1 FF FF90h
Duty Cycle/Capture 1
Register
COUNT2 FF FF92h Counter 2 Register
PERCAP2 FF FF94h
Period/Capture 2
Register
DTYCAP2 FF FF96h
Duty Cycle/Capture 2
Register
COUNT3 FF FF9Ah Counter 3 Register
PERCAP3 FF FF9Ch
Period/Capture 3
Register
DTYCAP3 FF FF9Eh
Duty Cycle/Capture 3
Register
COUNT4 FF FFA0h Counter 4 Register
PERCAP4 FF FFA2h
Period/Capture 4
Register
DTYCAP4 FF FFA4h
Duty Cycle/Capture 4
Register
7 6 5 4 3 2 1 0
TMOD2 T4RUN T3RUN TMOD1 T2RUN T1RUN
15 14 13 12 11 10 9 8
TMOD4 T8RUN T7RUN TMOD3 T6RUN T5RUN