LM8322EVALKIT National Semiconductor, LM8322EVALKIT Datasheet - Page 20

• Manufacturer Part Number: LM8322EVALKIT
• Description: BOARD EVALUATION LM8322
• Manufacturer: National Semiconductor

Specifications of LM8322EVALKIT

• Main Purpose: Interface, Special Purpose
• Embedded: No
• Utilized Ic / Part: LM8322
• Primary Attributes: Mobile I/O Companion with Key-Scan, I/O Expansion, PWM, Access.bus Host
• Secondary Attributes: Board has MCU for USB to PC GUI
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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14.4 RAMP COMMAND
The RAMP command generates a duty-cycle ramp starting
from the current value. At each step, the ramp counter is in-
cremented or decremented by one, unless it has reached its
its saturation value (0xFF for increment, or 0x00 for decre-
ment). The time for one step is controlled by the PRESCALE
bit and STEPTIME field. The minimum time for one step is
0.49 milliseconds. and the maximum time is about 1 second,
14.5 SET_PWM COMMAND
The SET_PWM command loads the ramp counter from the
8-bit DUTYCYCLE field in the instruction.
Please note: Only 0x00 and 0xFF are valid values for the duty
cycle in SET_PWM command. Other values can be estab-
14.6 GO_TO_START COMMAND
The GO_TO_START command jumps to the first command
in the script command file.
14.7 BRANCH COMMAND
The BRANCH command jumps to the specified command in
the script command file, with the option of looping for a spec-
ified number of repetitions. Nested loops are not allowed.
15
15
15
0
15
1
0
LOOPCOUNT
ADDRESS
INCREMENT
DUTYCYCLE
PRESCALE
Bit or Field
STEPTIME
Bit or Field
Field
14
1
14
14
0
PRESCALE
SIGN
14
13
0
13
13
1
12
0
12
Value
12
1–63
0–59
13
0
11
0
12
11
11
1–126
Value
Loop until a STOP PWM SCRIPT command is issued by the host.
Number of repetitions to perform, biased by -1. The range is 0–62 repetitions.
Branch destination address in the script command file. If this field is greater than 59, no
looping will be performed.
1–63
Value
STEPTIME
255
0
1
0
1
LOOPCOUNT
11
0
10
10
0
10
10
9
Divide the 32.768 kHz clock by 16
Divide the 32.768 kHz clock by 512
Number of prescaled clock cycles per step
Increment ramp counter
Decrement ramp counter
Number of steps executed by this instruction
9
0
Duty cycle is 0%.
Duty cycle is 100%.
9
9
8
8
0
8
8
20
0
7
7
which supports both very fast and very slow ramps. The IN-
CREMENT field specifies the number of steps to be executed
by the command. The maximum value is 126, which corre-
sponds to half of full scale.
There are two special cases in the instruction encoding. If all
bits and fields are 0, it is interpreted as the GO TO START
command. If the STEPTIME field is 0 but any other bit or field
is non-zero, it is interpreted as the SET_PWM command.
lished by initializing the duty cycle to either 100% or 0%
followed by a RAMP command.
SIGN
7
7
6
0
6
Description
6
6
5
Description
Description
5
5
5
DUTYCYCLE
4
4
4
4
INCREMENT
ADDRESS
3
3
3
3
2
2
2
2
1
1
1
1
0
0
0
0