
UM10800
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© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
269 of 487
NXP Semiconductors
UM10800
Chapter 16: LPC82x SCTimer/PWM
16.6.3 SCT control register
If bit UNIFY = 1 in the CONFIG register, only the _L bits are used.
If bit 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.)
Remark:
If CLKMODE = 0x3 is selected, wait at least 12 system clock cycles between a
write access to the H, L or unified version of this register and the next write access. This
restriction does not apply when writing to the HALT bit or bits and then writing to the CTRL
register again to restart the counters - for example because software must update the
MATCH register, which is only allowed when the counters are halted.
Remark:
If the SCTimer/PWM is operating as two 16-bit counters, events can only modify
the state of the outputs when neither counter is halted. This is true regardless of what
triggered the event.
12:9
INSYNC
-
Synchronization for input N (bit 9 = input 0, bit 10 = input 1,..., bit 12 = input 3);
all other bits are reserved. A 1 in one of these bits subjects the corresponding
input to synchronization to the SCT clock, before it is used to create an event.
If an input is known to already be synchronous to the SCT clock, this bit may be
set to 0 for faster input response. (Note: The SCT clock is the system clock for
CLKMODEs 0-2. It is the selected, asynchronous SCT input clock for
CLKMODE3).
Note that the INSYNC field only affects inputs used for event generation. It does
not apply to the clock input specified in the CKSEL field.
1
16:13
-
-
Reserved.
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.
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.
31:19
-
Reserved
-
Table 223. SCT configuration register (CONFIG, address 0x5000 4000) bit description
…continued
Bit
Symbol
Value
Description
Reset
value