228
Agere Systems Inc.
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
Data Sheet
July 2001
17 Key and Lamp Controller (KLC)
(continued)
17.3.2 KLC Noscan Control Register
The
noscan control register
contains the software reset bit and the keyboard noscan interval code. This register
is written to reset the KLC or to release the KLC from reset. If the reset bit is set to a 1, the KLC will reset, meaning
it will stop scanning buttons, set all lamp rates to off, and drive the
MSGLED
and
SPKRLED
outputs low. If the
reset bit is 0, then the KLC will start (or continue) operation. When the reset bit is changed from a 1 to a 0, the KLC
will exit reset at the next low to high transition of its 32 kHz clock and start its lamp timing cycle from the beginning.
During a reset the
MSGLED
and
SPKRLED
outputs will be driven active-low. The
lamp rate register
controlling
these outputs will be cleared to the default off state. When the reset is deasserted, the KLC will deassert these out-
puts, turning off the two LEDs.
Note:
The KLC does not come out of a software reset state until the microprocessor writes a 0 into the reset bit of
the
noscan control register
. A hardware reset will clear the KLC’s reset bit to 0 and will exit the reset state
as soon as the reset pin is low and the clock is present.
The microprocessor can change the noscan interval of the KLC through bits 0 and 1 of the
noscan control regis-
ter
. These bits will be reset to 1 (for the default interval) by a hardware reset. The noscan delay interval specifies
the amount of time the KLC will wait to scan the key matrix after detecting a key depression or release;
see Section
17.1.2 on page 224
.
Table 200. Lamp Rate Registers
Address 0xE000 D000, 0xE000 D06C, Write Only
5
4
Lamp B
Rate Bit 1
Rate bit 0
(LSB)
Address 0xE000 D070, Write Only
6:4
Speaker LED rate
Bit #
Name
7
6
3
2
1
0
RSVD
Lamp B
Rate bit 2
(MSB)
Lamp B
R’SRVD
Lamp A Rate
bit 2 (MSB)
Lamp A
Rate bit 1
Lamp A
Rate bit 0
(LSB)
Bit #
Name
31:7
3
2:0
Reserved
Reserved
Message LED rate
Table 201. Lamp Rate Bit Encoding
Bit 2
0
0
0
0
1
1
1
1
Bit 1
0
0
1
1
0
0
1
1
Bit 0
0
1
0
1
0
1
0
1
Flash Rate
Off.
Wink (200 ms on, 50 ms off).
Inverse wink (200 ms off, 50 ms on).
Inverse flash (500 ms off, 500 ms on).
Flash (500 ms on, 500 ms off).
Flutter (50 ms on, 50 ms off).
Broken flutter (500 ms of flutter, 500 ms off).
Steady on.