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參數(shù)資料
| 型號： | LM12434 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Sign Data Acquisition System with Serial I/O and Self-Calibration |
| 中文描述： | 注冊數(shù)據(jù)采集系統(tǒng)的串行I / O和自校準 |
| 文件頁數(shù)： | 39/80頁 |
| 文件大?。?/td> | 1561K |
| 代理商： | LM12434 |
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6.0 Operational Information
(Continued)
6.3 INSTRUCTION SEQUENCER
The Sequencer uses a 3-bit counter (Instruction Pointer, or
IP) to retrieve the programmable conversion instructions
stored in the Instruction RAM. The counter is reset to 000
during chip reset or if the current executed instruction has
its Loop bit (Bit 1 in any Instruction RAM ‘‘00’’) set high
(‘‘1’’). It increments at the end of the currently executed
instruction and points to the next instruction. It will continue
to increment up to 111 unless an instruction’s Loop bit is
set. If this bit is set, the counter resets to ‘‘000’’ and execu-
tion begins again with the first instruction. If all instructions
have their Loop bit reset to ‘‘0’’, the Sequencer will execute
all eight instructions continuously. Therefore, it is important
to realize that if less than eight instructions are pro-
grammed, the Loop bit on the last instruction must be set.
Leaving this bit reset to ‘‘0’’ allows the Sequencer to exe-
cute ‘‘unprogrammed’’ instructions, the results of which may
be unpredictable.
The Sequencer’s Instruction Pointer value is readable at
any time and is found in the Status register at Bits 8–10.
Figure 10 illustrates the instruction execution flow as per-
formed by the sequencer. The Sequencer can go through
eight states during instruction execution:
State 0:
The current instruction’s first 16 bits are read
from the Instruction RAM ‘‘00’’. This state is one clock cycle
long.
State 1:
Checks the state of the Calibration and Start bits.
This is the ‘‘rest’’ state whenever the Sequencer is stopped
using the reset, a Pause command, or the Start bit is reset
low (‘‘0’’). When the Start bit is set to a ‘‘1’’, this state is one
clock cycle long.
State 2:
Perform calibration. If bit 2 or bit 6 of the Configu-
ration register is set to a ‘‘1’’, state 2 is 76 clock cycles long.
If the Configuration register’s bit 3 is set to a ‘‘1’’, state 2 is
4944 clock cycles long.
State 3:
Run the internal 16-bit Timer. The number of
clock cycles for this state varies according to the value
stored in the Timer register. The number of clock cycles is
found by using the expression below
32T
a
2
where 0
s
T
s
2
16
b
1.
State 7:
Sample the input signal and read Limit
Y
1’s val-
ue if needed. The number of clock cycles for acquiring the
input signal in the 12-bit
a
sign mode varies according to
9
a
2D
where D is the user-programmable 4-bit value stored in bits
12–15 of Instruction RAM ‘‘00’’ and is limited to 0
s
D
s
15.
The number of clock cycles for acquiring the input signal in
the 8-bit
a
sign or ‘‘watchdog’’ mode varies according to
2
a
2D
State 6:
Perform first watchdog comparison. This state is
5 clock cycles long.
State 4:
Read Limit
Y
2. This state is 1 clock cycle long.
State 5:
Perform a conversion or second watchdog com-
parison. This state takes 44 clock cycles for a 12-bit
a
sign
conversions or 21 clock cycles for a 8-bit
a
sign conver-
sions. The ‘‘watchdog’’ comparison mode takes 5 clock cy-
cles.
39
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PDF描述 |
|---|---|
| LM12434CIV | Sign Data Acquisition System with Serial I/O and Self-Calibration |
| LM12434CIWM | Sign Data Acquisition System with Serial I/O and Self-Calibration |
| LM12454 | General Purpose Controller Z84C15 |
| LM12454 | 12-Bit Sign Data Acquisition System with Self-Calibration |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM12434CIV | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Sign Data Acquisition System with Serial I/O and Self-Calibration |
| LM12434CIWM | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Sign Data Acquisition System with Serial I/O and Self-Calibration |
| LM12438CIV | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Sign Data Acquisition System with Serial I/O and Self-Calibration |
| LM12438CIWM | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Sign Data Acquisition System with Serial I/O and Self-Calibration |
| LM12454 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:General Purpose Controller Z84C15 |
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