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参数资料
| 型号： | DEMOAPEXSENSOR |
| 厂商： | Freescale Semiconductor |
| 文件页数： | 13/20页 |
| 文件大小： | 0K |
| 描述： | BOARD DESIGN ALTITUDE PRESSURE |
| 标准包装： | 1 |
| 传感器类型： | 加速计，压力，水位，高度计/气压计 |
| 传感范围： | 多范围 |
| 接口： | I²C，SPI，模拟 |
| 灵敏度： | 多重 |
| 电源电压： | 10 V |
| 嵌入式： | 是，MCU，8 位 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MPX2102，MPXV5004G，MPL115A2，MMA7361L |
| 产品目录页面： | 2808 (CN2011-ZH PDF) |
Table 5.
ADC Type
24-bit
18-bit
Resolution ( μ V/ADC)
0.244 μ V
15.6 μ V per 1 ADC count
Resolution (kPa/ADC)
0.0000151 kPa
0.000963 kPa per 1 ADC count
DEMOAPEXSENSOR can read a 0.000963 (kPa/ADC count) step for a 0 to 100kPa MPXM2102A sensor.
The formulas earlier were shown to reference the pressure to altitude relationship.
Converting all this to altitude:
Table 6.
Distance
0.5 m
1m
3 ft
1 ft
Pressure (mB)
0.05
0.11
0.09
0.03
Pressure (kPa)
0.005
0.011
0.009
0.003
Voltage Change ( μ V)
0.81
1.78
1.46
0.49
ADC (counts)
5.19 so ~5
11.4 so ~11
9.35 so ~9
3.11 so ~3
Reviewing Table 6 , the DEMOAPEXSENSOR has code written to interpret small pressure changes and convert these to
altitude. The conversion from pressure to altitude still has to use the exponential equation for a proper conversion. But the
approximate distances and the ADC count equivalent are shown here. These are approximate across the pressure range but as
written in the demo code, the pressure is determined first, the altitude second. The altitude is calculated via the pressure value
inserted into the exponential altitude-pressure formula.
Experimental Altimetry Section
The preceding section on Altimetry has used the pressure sensor value to convert the pressure to an altitude reading. This
value of pressure is not linear with vertical height as detailed in the graph of Figure 6 . However if a curved line is magnified
enough, the end result can be treated as a straight line. The “Experimental” section of the Altimeter/Barometer tries this particular
method. Due to changing air currents and unstable smaller resolution, it may require outdoor demonstration to get better results.
In this example the chart outlines the calibration routine.
? To calibrate the part, first place the board on the floor or table in front of you.
? Wait until the low pass filtered value is stable then press Enter. This saves the “0 level” barometric pressure.
? Following this, place the board about 3 feet above the “0 level”. Either this is at waist height if previously on the floor, or
above your head if previously on the table. When the value stabilizes, press Enter again.
Now the display will output the distance in smaller increments than 1 foot. Notice how it tends to jump around, and the “0 level”
shifts. This Experimental section shows how this method while being more accurate is not as stable as the exponential method
to see pressure. The resolution is reasonable for a short period of time before barometric changes in pressure change the
calibration.
AN3956
Sensors
Freescale Semiconductor
13
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| DIP05-1A72-11D | RELAY REED SPST 1A 5V |
| DIP2415R | RELAY SSR 1.5A 20-280VAC RNDM |
| DK-1511-001/BL | CABLE RJ45 CAT5E W/BOOT 1' BLK |
| DK-1511-001/B | CABLE RJ45 CAT5E W/BOOT 1' BLUE |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DEMO-AT3/4-XX32 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:AT-32032 and AT-41532 demonstration for 800-900 MHz applications |
| DEMO-AT32063 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:860 MHz cascode amplifier |
| DEMO-AT3XX11 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:AT-31011 2400 MHz 2 stage LNA amplifier; can also be used for AT-30511 or AT-32011 |
| DEMO-AT3XX33 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:900 MHz single stage LNA amplifier using AT-32033; circuit can also be used for AT-30533 or AT-31033 |
| DEMO-ATF3616-3 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:2 to 2.4 GHz single stage LNA using ATF-36163 |
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