DocID025978 Rev 1
15/26
AN4450
Using the device step-by-step, from basic to advanced
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4
Using the device step-by-step, from basic to
advanced
4.1
First time bring-up (I²C example)
1. Start by using the same supply for VDD_IO and VDD to check device functionality.
2. Check supply impedances and ensure that all the pins voltages are in static condition.
3. The device is a slave with 1 byte sub-address which MSB should be ‘1’ to enable the
multiple data read/write at increasing addresses (bit 7 = 1 enables I²C sub-address
multi-byte auto-increment)
4. Use a normal I²C bus speed (<400 kHz)
5. Read the chip ID byte (sub address 0x0F, or 0x8F in case of auto-increment option):
0xBD should be read
4.2
Quick troubleshooting guide
If the device is not communicating properly on the I²C bus:
1.
If the I²C slave address is not acknowledged, check:
–
Power supply is present and matches the I²C master VDD_IO
–
I²C line pull-ups are present and with the correct values
–
The slave address is correctly selected
–
There are no other slaves with same address on the I²C bus lines.
–
Make sure the maximum I²C speed is driven by the slowest slave on the same I²C
bus.
–
Use an oscilloscope to check that the device acknowledges its slave address.
2. If the device responds and the pressure is always fixed and out of range (e.g. 760 mb),
make sure that AVGT and AVGP are in line with the specs and wait for the data ready
bit flag before reading the pressure registers.
3. If the device is reporting a value with a small offset compared to the expected one, a
single point calibration may be needed in order to compensate the post soldering
package stress (see
