SEN_16476 I2C communication issues

[MR_TakkaCor]

I am having problems communicating with the SEN-16476 breakout board (batch# 136973) that has the MPRLS0025PA00001A pressure sensor from Honeywell and QWIC connector. When I run a basic I2C write command, I don’t receive an ACK from the device (screenshot attached). I have confirmed that the board gets the appropriate SCL, SDA, VDD, and GND via oscilloscope and DMM.

I have used the documented default I2C address of 0x18 and every other combination of 7-bit I2C addresses, but none work.

Here are my parameters:

I2C SCL speed: 100 kHz

VDD I/O level: +3.3 V

Host processor: RM-191 module (runs a NRF51822 MCU) using smartbasic scripting language

I can confirm that this setup works for the SPX-17001 breakout board that has a BMP388 with QWIC connector, so I believe my I2C bus is setup correctly. Is is possible this batch of SEN-16476 has the SPI version of the chipset populated (i.e. MPRLS0025PA0000SA)? Is there any way to confirm the part number other than through an I2C command?

Any help you can give would be much appreciated, thanks in advance.

[TS-Chris]

We haven’t had any other customers report issues from this batch so I’m confident the correct part is on the board.

Do you have more than one sensor and if you do are they all not working? Have you tried a known good setup like a RedBoard Qwiic?

[MR_TakkaCor]

Hi, thanks for the response. I was able to get to a solution for my setup: I switched out the 2.2 kOhm pull-up resistors in SCL and SDA and made them weaker with 9.1 kOhm ones. It’s unclear why this would make a big difference since my current setup works with the SPX-17001 breakout board and that also has 2.2 kOhm resistors. I have no other I2C peripherals on the bus so the issue must be around the MPRL and my uController. Either way, I think I have a workable solution for now, thanks for the help.

[TS-Chris]

No problem, and glad you found a solution!

Your post will be helpful to another user if they run into the same situation.