How to choose the accelerometer recording frequency.

[GTell]

I have instaled the "ST BLE Sensor" on my smartphone and made some data collecting using accelerometer sensor. I have seen on the APP presentation that is possible to choose the frequency but I didn't find this option in the APP. I am seding a image of the APP section that show the option. If somemone could help to find this option, it will help me a lot on my researches.

Thank you.

[Eleon BORLINI]

Hi, I double-checked with our Bluecoin experts and we think it is not possible to change the ODR / rate settings directly form the app. I suggest you a longer way, if you want to going on in using this evaluation kit for deeper tests: you could change the FP-SNS-ALLMEMS2 on your PC in the right part of the code with your desired rate (ODR), and then download the modified FW on the Bluecoin. Btw, which is your target application (it will determine the acquisition band of interest)? Regards

[GTell]

Thank you for your answer.

I forgot to tell my model equipament is "STEVAL-STLKT01V1". I sought you mentioned the "blue coin". Can I do the same procedure on my device?

Regards.

[Eleon BORLINI]

​Hi Gustavo, in this case yes, the FP-SNS-ALLMEMS2 STM32Cube function pack works also with the Sensortile, the device you are using. You should download the function pack, open with IAR or a similar toolchain, modify the FW and then download your modified FW on the Sensortile MCU. This operation can of course be done both in .dfu mode and jtag mode. Regards

[GTell]

Hi Eleon. Thank you for your support. I am a beginner in using this kind of technology. Thus, I have some questions and I will be very appreciated with your answers.

First, I would like to know what is the sensor tile default frequency of acquisition?

Can I do the process of changing the frequency with the device I have or it is necessary to have other hardware?

Can you send me a step by step of how to do it?

I would like to set the frequency of aqusition in 100 Mhz.

Find attached the photo of my devices.

Best Regards.

[Eleon BORLINI]

hi Gustavo,

>> First, I would like to know what is the sensor tile default frequency of acquisition?

But did you refer to the overall acquisition frequency of the data or to the accelerometer ODR specifically?

>> Can I do the process of changing the frequency with the device I have or it is necessary to have other hardware?

Inside Driver, BSP, Components there are the configuration settings for the devices, such as the attached one. It enables you to change the default settings, but please take care of what you are doing because the code is not quite complex and the accelerometer for example could be used in different functions (AW, CP, FX etc...)

/*******************************************************************************
* Function Name : LSM303AGR_MAG_W_ODR
* Description : Write ODR
* Input : LSM303AGR_MAG_ODR_t
* Output : None
* Return : Status [MEMS_ERROR, MEMS_SUCCESS]
*******************************************************************************/
status_t LSM303AGR_MAG_W_ODR(void *handle, LSM303AGR_MAG_ODR_t newValue)
{
 u8_t value;
 
 if( !LSM303AGR_MAG_ReadReg(handle, LSM303AGR_MAG_CFG_REG_A, &value, 1) )
 return MEMS_ERROR;
 
 value &= ~LSM303AGR_MAG_ODR_MASK;
 value |= newValue;
 
 if( !LSM303AGR_MAG_WriteReg( handle, LSM303AGR_MAG_CFG_REG_A, &value, 1) )
 return MEMS_ERROR;
 
 return MEMS_SUCCESS;
}

[GTell]

Hi Eleon,

>>But did you refer to the overall acquisition frequency of the data or to the accelerometer ODR specifically?

I would like to know, what is the acquisition frequency of the accelerometer. The data frequency that will be exported in the CSV file.

Regards.

[Eleon BORLINI]

btw please ​consider that for the ALLMEMS_2 FW project you can find the actual axl ODR (e.g. of the LSM6DSM in the LSM6DSM_ACC_GYRO_driver_HL.c driver

/* Select default output data rate. */
2 pComponentData->Previous_ODR = 104.0f;

ref also to: https://community.st.com/s/question/0D50X0000AmkT3XSQU/change-defaut-value-for-odr-on-lmsd6-sensortile-allmems1-v340  

[Eleon BORLINI]

Hi Gustavo, ok I understand your point, the default ODR should be 100Hz. You can verify it acquiring the timestamp. Regards

[david binkowski]

Hi gustavo & Eleon

I see that i'm not alone to have the same question. My pb gustavo are the same of you, all ODR for the accelerometer, gyro etc are correct (100.4hz) but as i shown in my csv data collect by bluetooth with unicleo gui (ref to link ) my timestamp are near 50ms corresponding to 20hz.

I have found a older closed discution talking about that but without answer.

We need to distinguish several things:

- sensor ODR (output data rate) how often the sensor measure the data (Ok for us 104hz)

- data reading frequency, how often the microcontroller reads data from the accelerometer

- bluetooth characteristics update rate

This is the last 2 caracteristics we need to found. Even with new librairies ALLMEMS 2 default data reading frequency are 20Hz

If you have solution or find something i will be very gratefull, i trying to to do it since couple of days without any success...