LIS3MDL传感器为什么单位为LSB/Gauss的灵敏度

你好，
看看之前的讨论，我之前有过同样的问题：
https://community.st.com/0D50X00009XkXwiSAF
 大卫
 
 注意：原始帖子包含大量线程对话，只能迁移到第9级



以下为原文




Hello,
have a look at this earlier discussion, I had the same question before:
https://community.st.com/0D50X00009XkXwiSAF
David

Note: the original post contained a large number of threaded conversations and was only able to be migrated to the 9th level

关于多维数据集库中提到的代码中的值：
对于+/- 4高斯，灵敏度为6 842 LSB / gauss，意味着6 842 = 1高斯，12 964 = 2高斯，19 806 = 3高斯等...
 
但是，解释数据的一种方法是读取原始值并显示为miligauss。
如果1高斯= 6 842，那么1 000 mgauss = 6 842，意味着1 000 mgauss / 6 842 = 0,146156 mgauss / LSB。这同样适用于其他范围。它只是对相同数据的不同看法。
 
我个人更喜欢保持精度并尽可能在微控制器中使用整数数学，这就是为什么我编写自己的“驱动程序”来读取，计算和显示传感器的值。



以下为原文




Regarding the values in the code mentioned in the cube library:
For +/- 4 gauss, the sensitivity is 6 842 LSB / gauss, meaning 6 842 = 1 gauss, 12 964 = 2 gauss, 19 806 = 3 gauss, etc...

However, one way to interpret the data is to read the raw value and display as miligauss.
If 1 gauss = 6 842, then 1 000 mgauss = 6 842, meaning 1 000 mgauss / 6 842 = 0,146156 mgauss / LSB.The same applies to the other ranges. It is just a different look at the same data.

I personally prefer to keep the precision and use integer math as much as possible in microcontrollers, which is why I wrote my own 'driver' to read, compute and display the values from the sensor.

谢谢
Koudela.David.001
for你的回复。它给了我很多帮助。我仍然没有得到它100％。
原始等式是：
magnetic_intensity（高斯）= raw_data / sensitivity
因此，对于此等式，灵敏度是数据表中表格中的值（6842或2281 ......等）
我在这里纠正吗？
现在，关于LSB /高斯。我的理解是
6842 LSB = 1高斯，
6842 LSB = 1000 mgauss
因此，灵敏度= 6842/1000 = 6.842。
我的问题是你为什么以这种方式计算它？ （1000 mgauss / 6842 LSB = 0.14）
最后，在立方体库中，他们使用以下等式：mgauss =原始数据*灵敏度。
我们不应该使用这个（magnetic_intensity（高斯）= raw_data / sensitivity）？
我再次非常感谢你的帮助。
 
 注意：原始帖子包含大量线程对话，只能迁移到第9级



以下为原文




Thanks
Koudela.David.001
‌ for your reply. It helped me alot.I still did not get it 100%.
The original equation is:
magnetic_intensity (in gauss) = raw_data / sensitivity
So, for this equation the sensitivity is a value from the table in the datasheet(6842 or 2281...etc)
Am I correct here?
Now, regarding LSB/gauss. What I understand is
6842 LSB = 1 gauss,

6842 LSB = 1000 mgauss

So, sensitivity = 6842/1000 = 6.842.

My question is why did you calculate it in that way? (1000 mgauss / 6842 LSB = 0.14)

Last thing, in the cube library, they use this equation: mgauss = raw data * sensitivity.

Should not we use this one (magnetic_intensity (in gauss) = raw_data / sensitivity)?

Again, I really appreciate your help.

Note: the original post contained a large number of threaded conversations and was only able to be migrated to the 9th level

你好
khaledaljehani99
â€大江
Khaled Aljehani写道：
原始等式是：
magnetic_intensity（高斯）= raw_data / sensitivity
因此，对于此等式，灵敏度是数据表中表格中的值（6842或2281 ......等）
我在这里纠正吗？
是的，你是。
现在，关于LSB /高斯。我的理解是
6842 LSB = 1高斯，
6842 LSB = 1000 mgauss
因此，灵敏度= 6842/1000 = 6.842。
我的问题是你为什么以这种方式计算它？ （1000 mgauss / 6842 LSB = 0.14）
最后，在立方体库中，他们使用以下等式：mgauss =原始数据*灵敏度。
我们不应该使用这个（magnetic_intensity（高斯）= raw_data / sensitivity）？
 
如果您知道每1高斯（= 1 000 mgauss）的灵敏度为6 842 LSB，则至少有两种计算输出值的方法，传感器为您提供输出
- 32,768至32,767。
1）
magnetic_intensity = raw_data / sensitivity
以下单位：
[gauss] = [LSB] / [LSB / gauss]
所以灵敏度在这里表示为
这与数据表中印刷的值有关，并在链接的讨论中进行了讨论。
2）
magnetic_intensity = raw_data *灵敏度
以下单位：
[gauss] = [LSB] * [gauss / LSB]
所以灵敏度在这里表示为
无论您使用高斯还是高压计数都不会影响等式，只影响灵敏度系数（和/或结果）。
 
这与Cube库中的值有关。
0.14＆lt; 4高斯满量程的灵敏度值[mgauss / LSB]（= 0,000 14高斯/ LSB）
 
0.29＆lt; 8高斯满量程的灵敏度值[mgauss / LSB]（= 0,000 29高斯/ LSB）
 
0.43＆lt; 12高斯满量程的灵敏度值[mgauss / LSB]（= 0,000 43高斯/ LSB）
 
0.58＆lt; 16高斯满量程的灵敏度值[mgauss / LSB]
 （= 0,000 58高斯/ LSB）
 
-----
ST选择了第2版，但是，我更喜欢版本1。版本1可以更快，使用更少的资源，而且具有更高的精度！
如果在两种情况下灵敏度都是一个整数，它将执行相同的操作，但在这种情况下不是。
例1：
如果传感器给出6 842的输出，方法1将告诉您输出为1高斯。方法2将告诉您输出为957 mgauss（差异约为4％）。 （这也来自于这一事实
0,146156 mgauss / LSB舍入到0,14，而不是我预期的0,15。
您可能会说方法1只输出高斯中的整数值，并且您希望输出miligauss。没有问题，只需将raw_data与1000相乘就可以得到1000倍的更大结果（这就是你需要的，因为1 gauss = 1000 mgauss）。
例2，原始数据= 10 000：
方法1：
magnetic_intensity [mgauss] =（raw_data * 1 000）/灵敏度
磁场强度[mgauss] = 10 000 000/6 842 = 1 461 mgauss（= 1,461高斯）
方法2：
magnetic_intensity [mgauss] = raw_data *灵敏度
magnetic_intensity [mgauss] = 10 000 * 0,14 = 1 400 mgauss（= 1,400 gauss）=再次，约4％的误差
 
但是，方法1有一个缺点 - 如果您将输出值乘以（在此示例中为1 000），请确保您的数据类型将处理此问题。
在这种情况下，传感器raw_data是-32,768到32,767，乘以1 000得到-32 768 000到32 767 000，这很容易适合签名的int32，其中包括2,147,483,648到2,147,483,647。
您可以自己编写方法1的代码，只需使用raw_data作为signed int16作为参数调用下面的方法。
＆amp; sharpdefine DECIMAL_3DIGIT_FACTOR 1000u // 3小数点乘法
 
＆amp; sharpdefine COUNT_TO_GAUSS_4G_SCALE 6842; //每1高斯测量数据计数，满量程+/- 4 g
＆amp; sharpdefine COUNT_TO_GAUSS_8G_SCALE 3421; //每1高斯测量数据计数，满量程+/- 8 g
＆amp; sharpdefine COUNT_TO_GAUSS_12G_SCALE 2281; //每1高斯测量数据计数，满量程+/- 12克
＆amp; sharpdefine COUNT_TO_GAUSS_16G_SCALE 1711; //每1高斯测量数据计数，满量程+/- 16 g
//将磁力计数据（十六进制）转换为高斯单位
 
int32_t MM_Convert_To_Gauss（int16_t magnetometerData）{
 int32_t mgaussData;
 
mgaussData =（magnetometerData * DECIMAL_3DIGIT_FACTOR）;
mgaussData / = COUNT_TO_GAUSS_4G_SCALE;
 
 return gaussData;
}
 注意：原始帖子包含大量线程对话，只能迁移到第9级



以下为原文




Hello
khaledaljehani99
‌,
Khaled Aljehani wrote:
The original equation is:
magnetic_intensity (in gauss) = raw_data / sensitivity
So, for this equation the sensitivity is a value from the table in the datasheet(6842 or 2281...etc)
Am I correct here?
Yes, you are.
Now, regarding LSB/gauss. What I understand is
6842 LSB = 1 gauss,

6842 LSB = 1000 mgauss

So, sensitivity = 6842/1000 = 6.842.

My question is why did you calculate it in that way? (1000 mgauss / 6842 LSB = 0.14)

Last thing, in the cube library, they use this equation: mgauss = raw data * sensitivity.
Should not we use this one (magnetic_intensity (in gauss) = raw_data / sensitivity)?

There are at least two ways of calculating the output value, if you know that the sensitivity is 6 842 LSB per 1 gauss (=1 000 mgauss) and the sensor gives you output of
–32,768 to 32,767.

1)

magnetic_intensity = raw_data / sensitivity

with the following units:

[gauss] = [LSB] / [LSB/gauss]

so sensitivity is represented here as

This relates to the values printed in the datasheet and discussed in the linked discussion.

2)

magnetic_intensity = raw_data * sensitivity

with the following units:

[gauss] = [LSB] * [gauss/LSB]


so sensitivity is represented here as

The fact whether you count with gauss or miligauss doesn't affect the equation, just the sensitivity coefficients (and/or the result).


This relates to the values in the Cube library.

0.14 < Sensitivity value for 4 gauss full scale [mgauss/LSB] (= 0,000 14 gauss/ LSB)

0.29 < Sensitivity value for 8 gauss full scale [mgauss/LSB] (= 0,000 29 gauss / LSB)

0.43 < Sensitivity value for 12 gauss full scale [mgauss/LSB] (= 0,000 43 gauss / LSB)

0.58 < Sensitivity value for 16 gauss full scale [mgauss/LSB]
(= 0,000 58 gauss / LSB)



-----

ST chose version 2, however, I like version 1 more. Version 1 can be faster and use less resources, moreover, with a higher precision!

If the sensitivity was a round number in both cases, it would perform the same, but it is not in this case.
Example 1:

If the sensor gives you an output of 6 842, method 1 will tell you that the output is 1 gauss. Method 2 will tell you that the output is 957 mgauss (about 4 % difference). (This also comes from the fact that
0,146156 mgauss / LSB was rounded to 0,14, not 0,15 as I would expect).

You might say that method 1 output only an integer value in gauss and that you want output in miligauss. There is no problem with that, just multiply the raw_data with a 1000 and you get a 1000 x bigger result (which is what you need, because 1 gauss = 1000 mgauss).
Example 2, raw data = 10 000:

Method 1:


magnetic_intensity [mgauss] = ( raw_data * 1 000) / sensitivity


magnetic intensity [mgauss] = 10 000 000 / 6 842 = 1 461 mgauss (=1,461 gauss)
Method 2:


magnetic_intensity [mgauss] = raw_data * sensitivity


magnetic_intensity [mgauss] = 10 000 * 0,14 = 1 400 mgauss ( = 1,400 gauss) = again, about 4 % error





However, method 1 has a downside - if you multiply an output value (by a 1 000 in this example), make sure your data type will handle this.


In this case sensor raw_data is –32,768 to 32,767 , multiplied by 1 000 gives us -32 768 000 to 32 767 000 and this easily fits into a signed int32 with –2,147,483,648 to 2,147,483,647 range.
You can the code of method 1 on your own, just call the method below with raw_data as signed int16 as a parameter.


&sharpdefine DECIMAL_3DIGIT_FACTOR 1000u // 3 decimal points multiplication

&sharpdefine COUNT_TO_GAUSS_4G_SCALE 6842; // measured data count per 1 Gauss, full scale +/- 4 g
&sharpdefine COUNT_TO_GAUSS_8G_SCALE 3421; // measured data count per 1 Gauss, full scale +/- 8 g
&sharpdefine COUNT_TO_GAUSS_12G_SCALE 2281; // measured data count per 1 Gauss, full scale +/- 12 g
&sharpdefine COUNT_TO_GAUSS_16G_SCALE 1711; // measured data count per 1 Gauss, full scale +/- 16 g


// converts magnetometer data (hex) to Gauss unit

int32_t MM_Convert_To_Gauss (int16_t magnetometerData) {
int32_t mgaussData;
  
mgaussData = (magnetometerData * DECIMAL_3DIGIT_FACTOR);
mgaussData /= COUNT_TO_GAUSS_4G_SCALE;
  
return gaussData;
}
Note: the original post contained a large number of threaded conversations and was only able to be migrated to the 9th level

好解释
Koudela.David.001
“你真的帮助了我很多方程式。
我真的不明白为什么在数据表和应用说明中都没有添加这样的信息。
我想问一下，是否有计算输出值的参考？因为我搜索了很多，没有找到任何东西。
再次感谢您对我的努力。
 
 注意：原始帖子包含大量线程对话，只能迁移到第9级



以下为原文




Well explained
Koudela.David.001
‌You really helped me a lot with the equations.
I really do not understand why such an information is not added in either datasheet nor application note.
I want to ask, is there a reference for calculating the output values? Because I searched a lot and did not find any thing.
Again, thanks for your effort with me.

Note: the original post contained a large number of threaded conversations and was only able to be migrated to the 9th level

我很高兴你发现这些信息很有用。
正如你在前面的讨论中所看到的那样，同样的惊喜发生在我身上。我还认为这些简单的解释应该添加到数据表和/或相关的应用笔记中。
计算输出值的方法用于许多其他传感器（如果不是全部） - 加速度计，陀螺仪，压力传感器......



以下为原文




I am glad you find the information useful.
The same suprise happened to me, as you could see in the earlier discussion. I also think these simple explanations should be added to datasheet and/or the related application note.
The same way of computing output values is used for a lot of other sensors (if not all) - accelerometers, gyroscopes, pressure sensors...