lm8322 National Semiconductor Corporation, lm8322 Datasheet - Page 21

• Manufacturer Part Number: lm8322
• Description: Mobile I/o Companion Supporting Key-scan, I/o Expansion, Pwm, And Access.bus Host Interface
• Manufacturer: National Semiconductor Corporation

14.8 END COMMAND
The END command terminates script execution and asserts
an interrupt to the host if the RESET bit is set to “1” or “0”.
If the END command is executed with the RESET bit set to
“1” , the PWM output will be disabled. If the RESET bit is “0”
when executing the END command, the PWM channel re-
mains active with the fixed duty cycle it was last set to.
14.9 TRIGGER COMMAND
Triggers are used to synchronize operations between PWM
channels. A TRIGGER command that sends a trigger takes
sixteen 32.768 kHz clock cycles, and a command that waits
for a trigger takes at least sixteen 32.768 kHz clock cycles.
A TRIGGER command that waits for a trigger (or triggers) will
stall script execution until the trigger conditions are satisfied.
14.10 PWM SCRIPT EXAMPLE
This example shows a complex ramping sequence that uses
triggers for synchronization. Three scripts implement the ex-
ample. Figure 14 shows the PWM outputs for this example.
15
15
1
1
SENDTRIGGER
WAITTRIGGER
RESET
Bit
14
14
1
1
Field
13
13
0
1
Value
12
12
0
1
0
PWM_x output is active when script execution terminates.
PWM_x output is Tristate when script execution terminates.
0001xx
000xx1
000x1x
000xx1
000x1x
0001xx
RESET
11
Value
11
WAITTRIGGER
10
FIGURE 14. PWM Outputs
10
Wait for trigger from channel 2
Wait for trigger from channel 0
Wait for trigger from channel 1
Send trigger to channel 0
Send trigger to channel 1
Send trigger to channel 2
9
9
8
21
8
Please note: If a PWM channel is waiting for the trigger (last
executed command was "TRIGGER") and the script execu-
tion is halted then the "END" command can’t be executed
because the previous command is still pending. This is an
exception - in this case the IRQ signal will not be asserted.
Then, it will clear the trigger(s) and continue to the next com-
mand.
When a trigger is sent, it is stored by the receiving channel
and can only be cleared when the receiving channel executes
a TRIGGER command that waits for the trigger.
7
7
Description
6
6
Description
5
5
0
SENDTRIGGER
4
4
3
3
30013614
2
2
1
1
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