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  • Case ID: 360293
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Need urgent technical support for Nordic PMIC PM1300

Hemanth0

we are using nPM1300 EVK board for an upcoming project we are trying to interface PMIC PM1300 chip with Ambient Scientific processor GPx10 Pro.

It will be a huge setback for our project that is under development, if the I2C Interface between the two chips don’t work… since proto boards are already in fabrication

 

We have tested GPx10Pro I2C interface extensively with other sensors… but with this PMIC it is inconsistent and unreliable.  And this is the only part of Hardware that is not working yet.

In bare metal code, we are able to get acknowledgement sometimes. 

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  • 0

    Hi,

    As the I2C communication sometimes work but is unreliable the first thing that comes to mind is if you have long jumper wires when testing, perhaps combined with too weak pull-up resistors? I would suggest shortening the wires and using stronger (lower resistance) pull resistors.

  • 0 in reply to Einar Thorsrud

    Hi,

    we have tried with other pull up resistors still getting same results. we will once check by soldering the PMIC i2c pins with our mcu and will let you know the results.

  • 0 in reply to Hemanth0

    Hi,

    Can you double check (measure) the VDDIO voltage levels on both sides and show here so that we see clear evidence that you are using the same level? There is no VDDIO connection between the two boards, so you need to configure the same voltage on both ends. If that is not the case, and for instance the VDDIO voltage on the MCU is significantly lower, it could be that the logical 1 is in an undefined range seen from the nPM, in which case it could be expdected that comminication sometimes works, and sometimes fails. This is a key factor that shoudl be properly understood.

    Also, are there any level shifters or similar between the nPM and MCU (I do not know what the MCU board contains in the signal path). Any information on that could be usefull.

    The plot from June 2nd, can you confirm that it was measured on the nPM side?

    If the voltage level is the same on both the nPM and MCU we need to look closer, and then I would re-iterate the ask for a oscillioscope (analog) plot close to the nPM that shows both SDA and SCL (not just a logic analyzer plot, as that does not show us any information about the signal integrity).

  • 0 in reply to Einar Thorsrud

    Hi,

    please find the attached pictures regarding voltage calculations

    nPM VDDIO:



    our mcu VDDIO:




    Einar Thorsrud said:
    The plot from June 2nd, can you confirm that it was measured on the nPM side?

    yes it was measured from nPM side and there are no level shifters in between nPM and our MCU we are connecting SDA and SCL(which has 1.8Kohm pull up resistors) along with GND pins directly to the nPM from our MCU.

  • 0 in reply to Hemanth0

    That looks good. Please shere a SCL/SDA measured with oscilloscope when you are able to make that as well, as mentionned before.

    Edit: Can you also verify how you have connected toe pull resistors? Are they pulling up to VDDIO or something else?

  • 0 in reply to Einar Thorsrud

    Hi,

    as discussed yesterday we have removed the jumpers of P18 header to disconnect VOUT2. We soldered SDA,SCL,VDDIO(3.3V) and GND from our MCU eval board to P11 header respective pins. Still we are not getting ACK from the PMIC.

    Please find the below attched waveforms of SDA and SCL signals which were taken from PMIC side with oscilloscope:

    Let us know if anything need to be done.

  • 0 in reply to Hemanth0

    Hi,

    Thank you. This looks good and I do not see any obvious problems. Could it be that the nPM has been damaged during earlier testing? Do you have another nPM EK you can test with to see if that resolves the issue?

    Edit: One additional thing though, the can you zoom in so we see the timing better? The hold time seems to be quite low and then again rise time of the signals on the slow side. An alternative coudl be to test the EK with nPM PowerUp (from nRF Connect for Desktop) to see if it work there (put the P18 jumper back on when trying PowerUP).

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  • 0 in reply to Hemanth0

    Hi,

    Thank you. This looks good and I do not see any obvious problems. Could it be that the nPM has been damaged during earlier testing? Do you have another nPM EK you can test with to see if that resolves the issue?

    Edit: One additional thing though, the can you zoom in so we see the timing better? The hold time seems to be quite low and then again rise time of the signals on the slow side. An alternative coudl be to test the EK with nPM PowerUp (from nRF Connect for Desktop) to see if it work there (put the P18 jumper back on when trying PowerUP).

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