IIS2DH - 12-bit Resolution

[iaeinfach]

Hi,

I can only seem to read 10bit resolution despite setting the following:

REG_CTRL1 = 0b00000111;

REG_CTRL4 = 0b00001000;

I have low power mode disabled and HR mode enabled, but the precision does not increase from Normal Mode.

Am I missing something?

[Eleon BORLINI]

Hi, it should work.. Could you share e.g. the OUT_X_L (28h) and OUT_X_H (29h) values? do you concatenate it in the right way? Please consider that the sens is 3.91 mg/digit for NM and for 0.98 mg/digit in case of HR mode

[iaeinfach]

Here is the output of a resting module @ 2G / 25Hz ODR. I am reading values from the FIFO queue. I am triggering the read at the watermark level of 28.

High Res Mode

REG_CTRL1 = 0b00000111;

REG_CTRL4 = 0b00001000;

[98195] OUT_X_LH 00 80

[98214] OUT_X_LH 06 C0

[98236] OUT_X_LH 0C C0

[98257] OUT_X_LH 12 80

[98278] OUT_X_LH 18 C0

[98299] OUT_X_LH 1E 00

[98320] OUT_X_LH 24 00

[98342] OUT_X_LH 2A C0

[98363] OUT_X_LH 30 00

[98384] OUT_X_LH 36 00

[98405] OUT_X_LH 3C 00

[98426] OUT_X_LH 42 C0

[98448] OUT_X_LH 48 00

[98469] OUT_X_LH 4E C0

[98490] OUT_X_LH 54 00

[98511] OUT_X_LH 5A 00

[98532] OUT_X_LH 60 00

[98554] OUT_X_LH 66 C0

[98575] OUT_X_LH 6C 40

[98596] OUT_X_LH 72 00

[98617] OUT_X_LH 78 40

[98638] OUT_X_LH 7E 40

[98660] OUT_X_LH 84 00

[98681] OUT_X_LH 8A 00

[98702] OUT_X_LH 90 00

[98723] OUT_X_LH 96 C0

[98744] OUT_X_LH 9C C0

[98766] OUT_X_LH A2 00

Normal Mode

REG_CTRL1 = 0b00000111;

REG_CTRL4 = 0b00000000;

[58168] OUT_X_LH 00 C0

[58187] OUT_X_LH 06 40

[58209] OUT_X_LH 0C C0

[58230] OUT_X_LH 12 80

[58251] OUT_X_LH 18 40

[58272] OUT_X_LH 1E 80

[58293] OUT_X_LH 24 80

[58315] OUT_X_LH 2A 80

[58336] OUT_X_LH 30 40

[58357] OUT_X_LH 36 C0

[58378] OUT_X_LH 3C 40

[58399] OUT_X_LH 42 00

[58421] OUT_X_LH 48 00

[58442] OUT_X_LH 4E 80

[58463] OUT_X_LH 54 80

[58484] OUT_X_LH 5A 00

[58505] OUT_X_LH 60 00

[58526] OUT_X_LH 66 40

[58548] OUT_X_LH 6C 40

[58569] OUT_X_LH 72 00

[58590] OUT_X_LH 78 80

[58611] OUT_X_LH 7E 00

[58633] OUT_X_LH 84 C0

[58654] OUT_X_LH 8A 80

[58675] OUT_X_LH 90 C0

[58696] OUT_X_LH 96 40

[58717] OUT_X_LH 9C C0

[58739] OUT_X_LH A2 C0

Am I not converting correctly?

X = (int16_t)(i2c_read_data[i+1] << 8 | i2c_read_data[i]));

[iaeinfach]

Let me put it another way...

In HR Mode I expect raw values to change by a factor of 16.

In Normal Mode I expect raw values to change by a factor of 64.

In LP Mode I expect raw values to change by a factor of 256.

What I observe is the following:

HR Mode: 64

Normal Mode: 64

LP Mode: 256

So, I am not seeing 12-bit or at least there does not appear to be a difference between HR and Normal modes.

[iaeinfach]

So, now I see the issue. The FIFO only supports 10bit. Ugg.