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參數(shù)資料
| 型號： | SHT11 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | Humidity & Temperature Sensor |
| 中文描述： | 濕度 |
| 文件頁數(shù)： | 3/9頁 |
| 文件大?。?/td> | 840K |
| 代理商： | SHT11 |
SHT1x / SHT7x Relative Humidity & Temperature Sensor System
2.2.3 Sending a command
To initiate a transmission, a “Transmission Start” sequence
has to be issued. It consists of a lowering of the DATA line
while SCK is high, followed by a low pulse on SCK and
raising DATA again while SCK is still high.
www.sensirion.com
v2.02 July 2004
3/9
DATA
SCK
Figure 3
"Transmission Start" sequence
The subsequent command consists of three address bits
(only “000” is currently supported) and five command bits.
The SHTxx indicates the proper reception of a command by
pulling the DATA pin low (ACK bit) after the falling edge of
the 8th SCK clock. The DATA line is released (and goes
high) after the falling edge of the 9th SCK clock.
Table 2
SHTxx list of commands
2.2.4 Measurement sequence (RH and T)
After issuing a measurement command (‘00000101’ for RH,
‘00000011’ for Temperature) the controller has to wait for the
measurement to complete. This takes approximately
11/55/210 ms for a 8/12/14bit measurement. The exact time
varies by up to
±
15% with the speed of the internal oscillator.
To signal the completion of a measurement, the SHTxx pulls
down the data line and enters idle mode. The controller
must
wait for this “data ready” signal before restarting SCK to
readout the data. Measurement data is stored until readout,
therefore the controller can continue with other tasks and
readout as convenient.
Two bytes of measurement data and one byte of CRC
checksum will then be transmitted. The uC must
acknowledge each byte by pulling the DATA line low. All
values are MSB first, right justified. (e.g. the 5
th
SCK is MSB
for a 12bit value, for a 8bit result the first byte is not used).
Communication terminates after the acknowledge bit of the
CRC data. If CRC-8 checksum is not used the controller may
terminate the communication after the measurement data
LSB by keeping ack high.
The device automatically returns to sleep mode after the
measurement and communication have ended.
Warning:
To keep self heating below 0.1 °C the SHTxx
should not be active for more than 10% of the time
(e.g. max. 2 measurements / second for 12bit accuracy).
2.2.5 Connection reset sequence
If communication with the device is lost the following signal
sequence will reset its serial interface:
While leaving DATA high, toggle SCK 9 or more times. This
must be followed by a “Transmission Start” sequence
preceding the next command. This sequence resets the
interface only. The status register preserves its content.
DATA
SCK
Transmission Start
1
2
3
4 -8
9
Figure 4
Connection reset sequence
2.2.6 CRC-8 Checksumcalculation
The whole digital transmission is secured by a 8 bit
checksum. It ensures that any wrong data can be detected
and eliminated.
Please consult application note “CRC-8 Checksum
Calculation” for information on how to calculate the CRC.
DATA
SCK
a2
a1
C0
a0
C4
C3
C2
C1
ack
DATA
SCK
low
low
8
low
low
11
10
9
ack
7
6
0
5
4
3
2
1
ack
MSB
LSB
6
0
5
4
3
2
1
ack
LSB
DATA
SCK
7
MSB
Transmssion Start
Address=’000’
Command=’00101’
Measurement
~55ms for 12 bit
~11ms for 8 bit
Bold
= SHT1xx controls DATA line
Plain = uC controls DATA line
Measurement is finished when the
SHTxx pulls down the DATA line
Skip acknowledge to end transmssion
(if no CRC is used)
12 bit humdity data
CRC-8 Checksum
Skip acknowledge to
end transmssion
wait for next measurement
Transmssion Start
Figure 5
Example RH measurement sequence for value “0000’1001 ’ 0011’0001”= 2353 = 75.79 %RH
(without temperature compensation)
Command
Reserved
Measure Temperature
Measure Humidity
Read Status Register
Write Status Register
Reserved
Soft reset,
resets the interface, clears the
status register to default values
wait minimum 11 ms before next command
Code
0000x
00011
00101
00111
00110
0101x-1110x
11110
相關PDF資料 |
PDF描述 |
|---|---|
| SHT15 | Humidity & Temperature Sensor |
| SHT71 | Humidity & Temperature Sensor |
| SHT75 | Humidity & Temperature Sensor |
| SI-10022 | SI-10022 |
| SI-16001 | SI-16001 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| SHT11 | 制造商:Sensirion 功能描述:SENSOR HUMIDITY&TEMPERATURE |
| SHT11 | 制造商:Sensirion 功能描述:Humidity Sensor |
| SHT-110 | 功能描述:SHUNT TRIP MOD 110-130 VAC/DC 制造商:american electrical inc. 系列:- 零件狀態(tài):在售 配件類型:并聯(lián)跳閘裝置 配套使用產(chǎn)品/相關產(chǎn)品:UTS150N 斷路器 標準包裝:1 |
| SHT-1130L12VDC | 制造商:JAMECO RELIAPRO 功能描述:SOLENOID,12VDC,36 OHMS,CONT 4W,H FORCE, 0.63 LBS,PULL |
| SHT-12 | 功能描述:SHUNT TRIP MOD 12 VDC 30 MA 制造商:american electrical inc. 系列:- 零件狀態(tài):在售 配件類型:并聯(lián)跳閘裝置 配套使用產(chǎn)品/相關產(chǎn)品:UTS150N 斷路器 標準包裝:1 |
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