BMA2-Sensor-API bma2.c

[Coleman]

Hello

I am trying to set the registers for BMA253 and was looking at the source code - in BMA2-Sensor-API  bma2.c - and I have a few questions.

I am looking at v0.3.0 

On line 726, in bma2_set_accel_conf() function, it is reading the register 0x11(PMU_LPW) and that doesn't make sense.

below is the code snippet:

--------------------------------------------------------------------------------------------------------------------------------------------

Line726: rslt = bma2_get_regs(BMA2_REG_PMU_LPW, reg_data, 2, dev);
Line727:
Line728: if (rslt == BMA2_OK)
Line729: {
Line730: reg_data[0] = BMA2_SET_BITS_POS_0(reg_data[0], BMA2_RANGE, accel_conf->range);
Line731: reg_data[1] = BMA2_SET_BITS_POS_0(reg_data[1], BMA2_BW, accel_conf->bw);
Line732:
Line733: /* Set the values in the accel configuration registers */
Line734: rslt = bma2_set_regs(BMA2_REG_PMU_RANGE, reg_data, 2, dev);

--------------------------------------------------------------------------------------------------------------------------------------------

it is reading from 0x11(PMU_LPW) , setting the range and bandwith and writing it to 0x0F(PMU_RANGE).

shouldn' t it be getting from register 0x0F(PMU_RANGE)? (it doesn't really matter because PMU_LPW is 0x00 and you are setting the reg_data with your range and bw)

The code just after this is, I think, setting 0x3 in the reserved bit. (Line742)

code snippets below:

-------------------------------------------------------------------------------------------------------------------------

Line736: if (rslt == BMA2_OK)
Line737: {
Line738: reg_data[0] = BMA2_SET_BITS(reg_data[0], BMA2_SHADOW_DIS, accel_conf->shadow_dis);
Line739: reg_data[0] = BMA2_SET_BITS(reg_data[0], BMA2_DATA_HIGH_BW, accel_conf->data_high_bw);
Line740:
Line741: /* Set the values in the accel config register */
Line742: rslt = bma2_set_regs(BMA2_REG_ACCD_HBW, &reg_data[0], 1, dev);

-------------------------------------------------------------------------------------------------------------------------

when i printf the reg_data , reg_data[0] has 0x03 when setting data to register 0x13(ACCD_HBW).

In the case of BMA253, according to the data sheet, bit7 and bit6 is for data_high_bw and shadow_dis.

bit5 to bit0 are for reserved and setting 0x03 means strange because you set data on the reserved bit.

I think you have previous data (pmu range) in reg_data[0].

it seems that you should be calling bma2_get_regs() function with parameter 0x13(ACCD_HBW) before setting reg_data[0] on line738.

that's all. I appreciate if you could give me a feedback.

[FAE_CA1]

Hi,

Thanks for your feedback.

Please refer to the latest BMA2x2 API code at https://github.com/BoschSensortec/BMA2x2_driver/blob/master/bma2x2.c to see if the issue is still there or not.

Thanks.

[Coleman]

I am planning to use the BMA2x2_driver for my BMA253.

I guess the BMA2x2_driver doesn't have that issue.

So it is OK, thank you for the reply anyways.

The reason I was posting  a question was that:

I am planning to use the BMA2x2_driver bma2x2.c for BMA253, and I want to set the low-g interrupt (freefall detection).

But BMA2x2_driver bma2x2_support.c  didn't have an example to set the low-g interrupt.

So I was referencing the BMA2-Sensor-API example/low-g.c for setting up the BMA253 low-g interrupt.

While I was looking at BMA2-Sensor-API, I came across the code above (BMA2-Sensor-API bma2.c v0.3.0) and it didn't look right for BMA253.

I thought BMA2-Sensor-API supported BMA253 because it had an if statements for BMA2_BMA253_CHIP_ID in bma2_init() function.

[FAE_CA1 · Accepted solution]

Hi,

You can directly configure BMA253 for low-g interrupt without the need of using BMA2x2 API code. Please see the attached "How to generate freefall interrupt using BMA253.pdf" for more information.

Thanks.

[Coleman]

Thank you for the reply.

I will see the attached pdf file.