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Fahad Mirza
Fahad Mirza
Associate III
November 9, 2017
Solved

LIS2DE12 Accelerometer data bytes

  • November 9, 2017
  • 2 replies
  • 1728 views
Posted on November 09, 2017 at 22:50

http://www.st.com/content/ccc/resource/technical/document/datasheet/group0/72/cb/80/a7/5e/fe/46/9d/DM00153214/files/DM00153214.pdf/jcr:content/translations/en.DM00153214.pdf

says it provides 8-bit accelerometer value. But then again it says ''

The LIS2DE12 contains a 10-bit, 32-level FIFO''. Why?


_legacyfs_online_stmicro_images_0690X0000060MvBQAU.png

I am assuming it is 8bit, but then why do I need to read two bytes (for example, to get X-axis value from

OUT_X_H [29h] 

) ? Isn't it supposed to be 1 byte for a single axis, 3 bytes for a single FIFO and 96 bytes for whole FIFO as opposed to 2bytes, 6bytes and 192 bytes?
_legacyfs_online_stmicro_images_0690X0000060MvGQAU.png

#accelerometer #mems
This topic has been closed for replies.
Best answer by Miroslav BATEK
Posted on November 10, 2017 at 10:52

The LIS2DE12 reused a FIFO block from other device, that is why the FIFO store 10 bits, even if the accelerometer provides only 8bits.

When reading data from FIFO, it is possible to do three single byte read operations (OUT_X_H, 

OUT_Y_H, OUT_Z_H) but it is faster to perform one 6 bytes read operation and discard the unused bytes.

2 replies

M
Miroslav BATEKBest answer
ST Employee
November 10, 2017
Posted on November 10, 2017 at 10:52

The LIS2DE12 reused a FIFO block from other device, that is why the FIFO store 10 bits, even if the accelerometer provides only 8bits.

When reading data from FIFO, it is possible to do three single byte read operations (OUT_X_H, 

OUT_Y_H, OUT_Z_H) but it is faster to perform one 6 bytes read operation and discard the unused bytes.

Fahad Mirza
Fahad MirzaAuthor
Associate III
November 10, 2017
Posted on November 10, 2017 at 17:31

Thanks, Miroslav.

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