lm8328tmx National Semiconductor Corporation, lm8328tmx Datasheet - Page 16

• Manufacturer Part Number: lm8328tmx
• Description: Mobile I/o Companion Supporting Keyscan, I/o Expansion Pwm, And Access.bus Host Interface
• Manufacturer: National Semiconductor Corporation

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11.5 MULTIPLE KEY PRESSES
The LM8328 supports up to four simultaneous key presses.
Any time a single key is pressed KBDCODE0 is set with the
appropriate key code. If a second key is pressed, the key is
stored in KBDCODE1 and the MULTIKEY flag of KBDCODE0
is set. Additional key presses are stored in KBDCODE2 and
12.0 PWM Timer
The LM8328 supports a timer module dedicated to smooth
LED control techniques (lighting controls).
The PWM timer module consists of three independent timer
units of which each can generate a PWM output with a fixed
period and automatically incrementing or decrementing vari-
able duty cycle. The timer units are all clocked with a slow
(32.768 kHz) clock whereas the interface operates with the
main system clock.
12.1 OVERVIEW OF PWM FEATURES
•
•
Command
SET_PWM
TRIGGER
BRANCH
GO_TO_
START
Each PWM can establish fixed — or variable — duty-cycle
signal sequences on its output.
Each PWM can trigger execution of any pre-programmed
task on another PWM channel.
RAMP
END
15
0
0
1
1
1
PRESCALE
14
1
0
1
1
FIGURE 10. Example Keyscan Operation for 2 Key Press Events
13 12
1
0
1
TABLE 7. PWM Script Commands
1
and 1 Key Release Event
STEPTIME
INT
11
WAITTRIGGER
LOOPCOUNT
0
10
16
9
KBDCODE3 accordingly. The four registers signal the last
multi key press events.
All events are stored in parallel in the EVTCODE register for
the complete set of events.
All KBDCODE[3:0] registers are cleared on read.
•
•
•
12.2 OVERVIEW ON PWM SCRIPT COMMANDS
The commands listed in
PWM timers.
Please note: The PWM Script commands are not part of the
command set supported by the LM8328 command inter-
preter. These commands must be transferred from the host
with help of the register-based command set.
The execution of any pre-programmed task is self-
sustaining and does not require further interaction from the
host.
64-byte script buffer for each PWM for up to 32
consecutive instructions.
Direct addressing within script buffer to support multiple
PWM tasks in one buffer.
0
8
SIGN
7
ADDR
6
Table 7
X
SENDTRIGGER
PWMVALUE
5
INCREMENT
30124110
are dedicated to the slow
4
STEPNUMBER
3
2
1
0
0