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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
992 of 1441
NXP Semiconductors
UM10503
Chapter 31: LPC43xx/LPC43Sxx State Configurable Timer (SCT) with
31.3.2 SCT control register
If UNIFY = 1 in the CONFIG register, only the _L bits are used.
If UNIFY = 0 in the CONFIG register, this register can be written to as two registers
CTRL_L and CTRL_H. Both the L and H registers can be read or written individually or in
a single 32-bit read or write operation.
All bits in this register can be written to when the counter is stopped or halted. When the
counter is running, the only bits that can be written are STOP or HALT. (Other bits can be
written in a subsequent write after HALT is set to 1.)
17
AUTOLIMIT_L
-
A one in this bit causes a match on match register 0 to be treated as a de-facto
LIMIT condition without the need to define an associated event.
As with any LIMIT event, this automatic limit causes the counter to be cleared to
zero in uni-directional mode or to change the direction of count in bi-directional
mode.
Software can write to set or clear this bit at any time. This bit applies to both the
higher and lower registers when the UNIFY bit is set.
0
18
AUTOLIMIT_H
-
A one in this bit will cause a match on match register 0 to be treated as a
de-facto LIMIT condition without the need to define an associated event.
As with any LIMIT event, this automatic limit causes the counter to be cleared to
zero in uni-directional mode or to change the direction of count in bi-directional
mode.
Software can write to set or clear this bit at any time. This bit is not used when
the UNIFY bit is set.
0
31:19
-
Reserved
-
Table 747. SCT configuration register (CONFIG, address 0x4000 0000) bit description
…continued
Bit
Symbol
Value
Description
Reset
value
Table 748. SCT control register (CTRL, address 0x4000 0004) bit description
Bit
Symbol
Value
Description
Reset
value
0
DOWN_L
-
This bit is 1 when the L or unified counter is counting down. Hardware sets this bit
when the counter limit is reached and BIDIR is 1. Hardware clears this bit when the
counter reaches 0 or when the counter is counting down and a limit condition occurs.
0
1
STOP_L
-
When this bit is 1 and HALT is 0, the L or unified counter does not run but I/O events
related to the counter can occur. If such an event matches the mask in the Start
register, this bit is cleared and counting resumes.
0
2
HALT_L
-
When this bit is 1, the L or unified counter does not run and no events can occur. A
reset sets this bit. When the HALT_L bit is one, the STOP_L bit is cleared. If you
want to remove the halt condition and keep the SCT in the stop condition (not
running), then you can change the halt and stop condition with one single write to
this register.
Remark:
Once set, only software can clear this bit to restore counter operation.
1
3
CLRCTR_L
-
Writing a 1 to this bit clears the L or unified counter. This bit always reads as 0.
0
4
BIDIR_L
L or unified counter direction select
0
0
Up. The counter counts up to its limit condition, then is cleared to zero.
1
Up-down. The counter counts up to its limit, then counts down to a limit condition or
to 0.