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嗨,
我正在研究一个使用LIS2DH传感器来测量沿X,Y和Z轴的加速度的项目。我按照以下配置配置了IC: - 1>使用8位分辨率捕获X,Y和Z轴的数据。 2>我们启用了该传感器的低功率模式。 3>我们将ODR设置为50 Hz。 当我们将满量程值设置为+/- 4g时,我们得到OUT_X寄存器的默认值为0,OUT_Y寄存器为0,OUT_Z寄存器为30,因为沿Z方向有一个恒定的加速度,由于重力,幅度为1g当设备是静态的。由于我们使用的是8位寄存器,因此范围可以在-128到+127之间变化,因此可以实现的默认幅度为32 * 30(根据数据表,1LSb = 32mg),即0.96g,大约等于1g 。 当我们将全值设置为+/- 8g时,当设备沿Z轴静止时的默认值是15,因此15 * 64(根据数据表为1LSb = 64mg),即0.96g,大约等于1g。 当我们将满量程值设置为+/- 16g时,设备沿Z轴静态时的默认值为5,因此5 * 192(根据数据表为1LSb = 192mg),即0.96g,约为1g但是当我们通过乘以192 * 127来计算满量程值时(因为可以在8位有符号寄存器中设置的最大值是+127),即24.34g远远大于设定的满量程值,即+/- 16g,但在上述两种情况下,我得到了正确的满量程值FS = + / - 4g(127 * 32)即4.064g,当FS = + / - 8g(127 * 64)即8.1g时,为什么我得到了计算出的满量程值远高于设定的满量程值,即+/- 16g? 数据表和这里提到的部分是'LIS2DH MEMS数字输出运动传感器:超低功耗高性能3轴“飞行加速度计”和2.1节“机械特性”。 以上来自于谷歌翻译 以下为原文 Hi, I am working on a project that is using LIS2DH sensor for measuring the acceleration along the X,Y and Z-axis. I have configured the IC as per the following configurations:- 1>Using the 8-bit resolution to capture the data of X,Y and Z-axis. 2>we have enabled the low power mode of this sensor. 3>We have set the ODR as 50 Hz. when we set the full scale value as +/-4g, then we get the default value for OUT_X register as 0, OUT_Y register as 0 and OUT_Z register as 30 since there is a constant acceleration along Z direction with magnitude of 1g due to gravity when the device is static. Since we are using 8-bit register the range can be vary from -128 to +127, so the default magnitude that can be achieved is 32*30 (1LSb = 32mg as per data sheet) i.e. 0.96g which is approximately equals to 1g. When we set the full value to +/-8g then the default value when the device is static along the Z-axis is 15 so 15*64 (1LSb = 64mg as per datasheet ) i.e. 0.96g which is approx equals to 1g. And when we set the full scale value to +/-16g then the default value when the device is static along the Z-axis is 5 so 5*192 (1LSb = 192mg as per data sheet) i.e. 0.96g which is approx 1g too but here when we calculate the full scale value by multiplying 192*127(because maximum value that can be set in 8-bit signed register is +127) i.e. 24.34g which is much far greater than the set full scale value i.e. +/-16g but in the above two cases i got the correct full scale values FS=+/-4g (127*32) i.e 4.064g and when FS=+/-8g (127*64) i.e 8.1g, so why i got the calculated full scale value much above the set full scale value i.e +/-16g ? The datasheet and the section that is refer here is 'LIS2DH MEMS digital output motion sensor:ultra low-power high performance 3-axis “femtoâ€� accelerometer' and section 2.1 'Mechanical characteristics' respectively. |
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你好,
我相信答案与我在这里提到的磁力计比例的类似问题相同: https://community.st.com/thread/40903-lis3mdl-data-interpretation&sharpcomment-157266 (查看下面的答案)。长话短说,根据您提到的机械特性部分是典型的提供范围(并且灵敏度也表示为典型值),因此传感器不能保证为您提供完全比例输出。 注意:原始帖子包含大量线程对话,只能迁移到第9级 以上来自于谷歌翻译 以下为原文 Hello, I believe the answer is the same as to my similar question to a magnetometer scale asked here: https://community.st.com/thread/40903-lis3mdl-data-interpretation&sharpcomment-157266 (check the answer below).Long story short, according to the Mechanical characteristics section you mentioned is the provided range typical (and also the sensitivity is stated as typical), so the sensor is not guaranteed to give you the full proportional output. Note: the original post contained a large number of threaded conversations and was only able to be migrated to the 9th level |
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嗨,
谢谢你的宝贵回复。可以保证超出范围值但是当我将设备置于静态位置时(即图中没有运动),则OUT_X寄存器中显示的值为0,OUT_Y寄存器为0且OUT_Z寄存器是5。 1)这些默认值是否正确,因为根据数据表,FS = + / - 16g和1LSb = 192mg,因此5 * 192 = 960mg(0.96g).. 2)当我用光滑的手沿着Z轴摇动设备时,它沿Z轴给出109的值,等于109 * 192 = 20g(根据计算),但我不认为加速度不是那么多(大致在2g到3g左右)。这种变化的确切原因是什么? 以上来自于谷歌翻译 以下为原文 Hi, Thanks for your valuable reply. It's okay that the out of range values are not guaranteed but when i put my device into the static position(i.e. there is no motion in the picture), then the values shown in the OUT_X register is 0, OUT_Y register is 0 and OUT_Z register is 5. 1) So are these default values correct or not, because FS=+/-16g and 1LSb = 192mg as per datasheet so 5*192 = 960mg( 0.96g).. 2) when i shake the device along Z-axis by smooth hands it is giving the value of 109 along Z-axis which equals to 109*192 = 20g(as per the calculation) but i don't think acceleration is not that much (roughly it's around 2g to 3g). What is the exact reason for such variation? |
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你好,
1)是的,这些值对于静止设备是合理的。 X和Y为零,因为这些方式的地球加速度几乎为零。由于地球的重力加速度,Z应该输出1 g(= 9,806 m / s ^ 2,具体取决于您的位置,但差异将与传感器比例和噪声大致相同)。 我建议围绕所有轴旋转设备以进行简单评估。 2)20克太多,正如你所说,2 - 3克可以。我试着用一块板子严重摇晃 http://www.st.com/en/mems-and-sensors/lis3mdl.html 安装,结果如下:您可以粘贴您的传感器设置和输出值,以供ST的某人检查。 (或者如果您可以在某些操作期间从输出值创建类似于我的图形,旋转等) 以上来自于谷歌翻译 以下为原文 Hello, 1) Yes, these values are reasonable for a still device. X and Y are zero, because the earth acceleration in these ways is practically zero. Z should give an output of 1 g (= 9,806 m/s^2, depending on your location, but the difference will be approximately the same as the sensor scale and noise) because of a Earth's gravitational acceleration. I recommend rotating the device around all axles for a simple evaluation. 2) 20 g is too much, as you say, 2 - 3 g could be OK. I tried shaking heavily with a board with an http://www.st.com/en/mems-and-sensors/lis3mdl.html mounted and here is the result:You can paste your sensor setup and output values to be checked by someone from ST. (Or if you can create a graph similar to mine from your output values during some operations, rotating etc.) |
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嗨大卫,
我非常感谢您的回复,请您与我分享源代码,以便我知道您是使用FIFO还是直接从寄存器读取值。如果已使用FIFO,那么您已完成的其他寄存器的配置是什么? 以上来自于谷歌翻译 以下为原文 Hi David, I am really grateful that you've replied, Would you please share the source code with me so that i can know whether you have used FIFO or read the values direct from the registers. If the FIFO has been used then what are the configurations of the other registers that you've done? |
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你好Mohit,
上面附带的截图来自a http://www.st.com/en/embedded-software/bluems.html ,连接到http://www.st.com/content/st_com/en/products/embedded-software/mems-and-sensors-software/open-mems/bluemicrosystem1.html 扩展软件。带有源代码的软件可以在页面底部自由下载(我还没有研究过这个代码部分,所以我担心你需要自己深入研究。)我用这个硬件进行一些基本测试传感器(也可以使用其他一些Nucleo和扩展板): http://www.st.com/content/st_com/en/products/ecosystems/stm32-open-development-environment/stm32-nucleo-expansion-boards/stm32-ode-sense-hw/x-nucleo-iks01a1。 HTML http://www.st.com/content/st_com/en/products/ecosystems/stm32-open-development-environment/stm32-nucleo-expansion-boards/stm32-ode-connect-hw/x-nucleo-idb05a1。 HTML http://www.st.com/en/evaluation-tools/nucleo-l476rg.html?icmp=pf261636_pron_pr_sep2015&sc=nucleo-l476rg 以上来自于谷歌翻译 以下为原文 Hello Mohit, The screenshot attached above is from a http://www.st.com/en/embedded-software/bluems.html , connected to a http://www.st.com/content/st_com/en/products/embedded-software/mems-and-sensors-software/open-mems/bluemicrosystem1.html expansion software. The software with source code can be downloaded freely at the bottom of the page (I haven't studied this code part yet, so I am afraid you will need to dive into that yourself.)I use this HW for basic testing of a few sensors (also a few other Nucleo and expansion boards can be used): http://www.st.com/content/st_com/en/products/ecosystems/stm32-open-development-environment/stm32-nucleo-expansion-boards/stm32-ode-sense-hw/x-nucleo-iks01a1.html http://www.st.com/content/st_com/en/products/ecosystems/stm32-open-development-environment/stm32-nucleo-expansion-boards/stm32-ode-connect-hw/x-nucleo-idb05a1.html http://www.st.com/en/evaluation-tools/nucleo-l476rg.html?icmp=pf261636_pron_pr_sep2015&sc=nucleo-l476rg |
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