AN4159

Software

Doc ID 023639 Rev 3

19/27

All the needed coefficients to compute the quadratic pressure in the microcontroller are

available within the sensor registers. A reference C source code (using floating point or non-

floating point arithmetic) is available.

6.2.8

Self test

Devices can be self tested to a certain degree:

●

If the I2C slave address is not acknowledged, the power supply, I2C lines and pull-ups

are missing or the wrong slave address has been selected

●

If the device respond and the pressure is always fixed and out of range (e.g. 760 mb),

check that if you are using the auto reporting of the ODR, make sure that Tave and

Pave is in line with the specs and if u are in one shot mode, waiting for the data ready

bit flag before to do a read pressure, if all configurations are in line and the pressure is

still fixed at 760mb, the sensing element (PZT membrane/bonding wires between

sensing element and ASIC) is damaged. Do a registers dump for us to do a diagnostic.

This feature is available on FROG. LGA socket to UNICO adapter is available,

especially for failure analysis preliminary report.

●

A very big or “negative” pressure could come from bonding wire being cut by

mishandling of the device (bonding between sensing element and ASIC)

●

An example of C type self-test function is available

6.2.9

Questions and answers

Case 1:

“We are testing the barometer board through 4 wire SPI interface.

After setting CTRL_REG1 (0x20) to 0xF0, we are polling STATUS_REG (0x27) and

PRESS_OUT_XL/L/H, TEMP_OUT_L/H every second.

The value of STATUS_REG is 0x11 for every read.

The temperature values are updating correctly; it’s about 22.5 °C after the conversion, and

goes up if I put my hand on the board.

However, the pressure value is always constant at 0x2f8000 (PRESS_OUT_H &

PRESS_OUT_L & PRESS_OUT_XL); it does not seem to work properly.

Are there any additional configurations required?”

●

RES register was set to @0x10 = 0x7 A while ODR was set to (25 Hz, 25 Hz). Solved

by changing RES to 0x79 or ODR to (12.5 Hz, 12.5 Hz).