LIS2DE12 pull up resistor values

[RKeit.1]

Hi,

I have been using the LIS3DH successfully but I want to go to the LIS2DE12 because it is smaller and only does what I need. I have wired up a STEVAL-MKI175V1 board to a 3.3 v Arduino close to do some initial evaluation. I can't get it to respond at all. I am wondering if I have my resistor values wrong.

I am using I2C so CS is help high using a 10 k pull up resistor.

SCL and SDA both have 10 k pull up resistors. There is nothing else on the bus at this time.

SDO/SAO is tied to ground. I have also let it float but get no response either way.

I have used this exact setup with an LIS3DH. That works fine.

There is no mention of the values of pull up resistors in the datasheet. Is 10 k appropriate?

Also, there is also the chance I have fried the demo board. In my experience these devices are very robust. I don't remember doing anything and the only voltage nearby is 3.3 volts. Maybe I did something careless. I have ordered another one. Is there something obvious , such as reverse polarity, that might kill them?

Thanks in advance,

Rob

[Eleon BORLINI]

Hi @RKeit.1​ , are the other pins of the LIS2DE12 correctly connected as described in the datasheet p.9? I would btw suggest you to wire the CS directly to Vdd or Vdd_IO (Vdd >= Vdd_IO) and maybe to reduce the pull-up resistor to 4.7kOhm (but only to try a different value, because 10kOhm should be ok as well...). Regards

[RKeit.1]

Hi Eleon,

Thanks for the reply.

I have wired it exactly the same as the LIS3DH I have set up to test. The only difference is that I used to use the LIS3DH with 4.7 k pullups and went to 10 k because I had another device in parallel.

I just tried it with 5k on SCL and SDA. Still no luck. I think it is fried.

Regards,

Rob

[RKeit.1]

I have got it working.

I bought another STEVAL-MKI175V1 and it behaved exactly the same as the first one.

There is no way I could get the LIS2DE12 working with an Arduino. I tried four different 3.3 volt Arduino clones with various MCUs and non of them worked. I could get a response to Who Am I only after disconnecting and re-connecting the ground pin. Any read or write other registers failed.

I am developing a device using a Silicon Labs low powered MCU, EFM8SB2. I needed to buy a new dev board because my old one stopped working. Today I hooked it up to the STEVAL-MKI175V1 and it worked flawlessly with either 4.7 or 10 k pullups.

The SiLabs MCU has a "hardware" SMBUS controller, which I set to 10 kHz. It seems to be very robust.

The question remains: Why would the LIS3DH work fine with Ardionos and the LIS2DE12 not work at all?

Rob

[RKeit.1]

I found the problem.

The LIS2DE12 does not work at all with Arduinos with the SDO pin pulled to ground.

It does not work reliably with any other I2C master I have tried with the SDO pin pulled to ground. It also draws really excessive current all the time, making it unsuitable for use with battery powered devices in that configuration. This is evidently known to ST personnel but they did not bother to include the information in any of the documentation. I have wasted days on this problem.

It works very well with the SDO pin left floating. Current consumption is as documented.

Rob