LIS2HH12 with DMA

[Alexandre T]

Posted on November 03, 2017 at 09:55

Hello,

I implemented a DMA with my LIS2HH12 to avoid losing datas.

The problem is that my DMA is too fast, I am able to read at 1.8kHz (1800 (x,y,z) datas in 1 second) thanks to my DMA but the max ODR that I can choose on my accelerometer is 800Hz.

So I am wasting a lot of memory with my DMA cause if I choose a 400Hz ODR if have a new data available each 4 or 5 sample.

As I understood, it is not possible to change the DMA speep. Did I miss something on the datasheet that could help me to solve my problem ? 

FIFO is interesting but while reading all the registers to get (x,y,z) datas, I will loose some datas ?

Note : I don't want an interrupt when new data available cause it will stop my program everytime

[Miroslav BATEK]

Posted on November 05, 2017 at 21:40

I think the best solution is to use FIFO and read the data in bursts. You can configure INT1 to generate an interrupt if FIFO reach a certain level and then read all the data in FIFO using DMA. This approach will reduce number of interrupts and avoid any data loss.

[Alexandre T]

Posted on November 06, 2017 at 09:23

I imagined an other solution using a timer and the DMA TC interrupt. I'll try both

[Alexandre T]

Posted on November 06, 2017 at 16:57

I am currently trying to implement your solution but I don't really understand the 5.3.3 chapter in the datasheet. If I want to have 20 values available when the interrupt occurs. What should I put in FIFO_CTRL(FTH4:0) and how many samples I need to read ?