UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
129 of 362
NXP Semiconductors
UM10208
Chapter 10: LPC2800 Timer
3.2 Load registers
3.3 Value registers
3.4 Control registers
3.5 Interrupt Clear registers
Table 125:
Load registers (T0LOAD, T1LOAD - 0x8002 0000, 0x8002 0400)
Bit
Symbol
Description
Reset
value
31:0
Software can write to this address at any time, to immediately load the
value written into both the main 32-bit counter and a 32-bit reload
register, from which the main counter can be reloaded when it counts
down to 0. Reading this address returns the contents of the reload
register.
undef
Table 126:
Value registers (T0VALUE, T1VALUE - 0x8002 0004, 0x8002 0404)
Bit
Symbol
Description
Reset
value
31:0
Software can read this address at any time, to obtain the current value
of the main 32-bit counter.
undef
Table 127:
Control registers (T0CTRL, T1CTRL - 0x8002 0008, 0x8002 0408)
Bit
Symbol
Description
Reset
value
1:0
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
3:2
PRESCALE This field controls how the CGU clock is prescaled before being
applied to the main counter:
00: decrement main counter at CGU clock rate
01: decrement main counter at CGU clock rate / 16
10: decrement main counter at CGU clock rate / 256
11: do not write
undef
5:4
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
6
TMODE
This bit controls what happens when the main counter has counted
down to zero:
0: the next clock decrements the counter to all ones (0xFFFF FFFF)
1: the next clock loads the main counter with the value in the reload
register
undef
7
TENAB
A 1 in this bit allows the counter to run. A 0 disables counting.
0
31:8
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
Table 128:
Interrupt Clear Registers (T0CLR, T1CLR - 0x8002 000C, 0x8002 040C)
Bit
Symbol
Description
Reset
value
31:0
Each timer always asserts its interrupt request when it counts down to
zero. Writing any value to this write-only address clear the timer’s
interrupt request.
n/a