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Not getting 1.8 volt on the SIM_1V8 pin on custom board

We had a custom board made with the nrf9160 and I noticed I was having trouble communicating with the sim card on my board.

We have been testing i2c, spi, number of peripherals (a display, memory, etc).  Even GPS was working well with the latest 1.1.0 modem FW.  But I'm getting an error communicating with the SIM card.  I noticed that the Nordic is not outputting 1.8V on the SIM_1V8 line.  I noticed the IO_Supply line has 2.222V on it which is the same as the DK, so I'm assuming that's ok.

I noticed this post: https://devzone.nordicsemi.com/f/nordic-q-a/47633/not-getting-1-8-volt-in-sim_1v8-pin  But it seems the solution here was that they needed to reflow the board and it was a mechanical problem.  I've tested 4 different boards all made from a reputable assembly house we have used in the past.  Also tested the nrf52 that's on the board with smaller pitch and that works.  And so does everything else we have tested on the nrf9160 side and so far so good.

Anything I'm missing to enable that output?  What might I need to turn on that 1.8V output.  I noticed if I put my code on the DK using the JLink that line on the DK is 0V.  But if I hook up to the DK with the normal USB and run a sample project that pin has 1.8V on it. 

  • I noticed if I put my code

    What code/sample are you using here ?

    I believe you need to have CONFIG_BSD_LIBRARY=y i prj.conf in order for the modem to output 1.8V on the SIM pin.

  • Well I'm trying to make my own project.  It's mostly based off the UDP_GPS code sample.  And I have the CONFIG_BSD_LIBRARY=y in my prj.conf file.  And the 1.8V is off on that pin.

    This is my prj.conf file:

    CONFIG_NEWLIB_LIBC=y
    CONFIG_BSD_LIBRARY=y
    CONFIG_GPIO=y
    CONFIG_SERIAL=y
    CONFIG_STDOUT_CONSOLE=y
    CONFIG_UART_INTERRUPT_DRIVEN=y
    CONFIG_TEST_RANDOM_GENERATOR=y
    CONFIG_NETWORKING=y
    CONFIG_NET_BUF_USER_DATA_SIZE=1
    CONFIG_NET_SOCKETS_OFFLOAD=y
    CONFIG_NET_SOCKETS=y
    CONFIG_NET_SOCKETS_POSIX_NAMES=y
    CONFIG_TRUSTED_EXECUTION_NONSECURE=y
    CONFIG_LOG=y
    CONFIG_LOG_DEFAULT_LEVEL=4
    
    # Heap and stacks
    CONFIG_HEAP_MEM_POOL_SIZE=16384
    CONFIG_MAIN_STACK_SIZE=8192
    CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
    
    CONFIG_MAIN_THREAD_PRIORITY=7
    
    # LTE link control
    CONFIG_LTE_LINK_CONTROL=y
    CONFIG_LTE_PSM_REQ_RPTAU="00101010"
    CONFIG_LTE_PSM_REQ_RAT="00000001"
    CONFIG_AT_HOST_LIBRARY=y
    
    CONFIG_LTE_AUTO_INIT_AND_CONNECT=n
    CONFIG_LTE_LINK_CONTROL_LOG_LEVEL_DBG=y
    CONFIG_LTE_NETWORK_MODE_NBIOT=n
    CONFIG_LTE_LEGACY_PCO_MODE=n

    It's exactly the same as the sample project that I believe works. But that project also has these items in it's prj.conf file:

    CONFIG_FP_SHARING=y
    CONFIG_NORDIC_SECURITY_BACKEND=y
    CONFIG_CC310_BACKEND=y
    
     # GPS
    CONFIG_NRF9160_GPS=y
    CONFIG_NRF9160_GPS_LOG_LEVEL_DBG=y
    CONFIG_GPS_USE_EXTERNAL=y
    CONFIG_GPS_DEV_NAME="NRF9160_GPS"
    
    CONFIG_GPS_CONTROL=y
    CONFIG_GPS_CONTROL_FIRST_FIX_CHECK_DELAY=10
    CONFIG_GPS_CONTROL_FIX_COUNT=3
    CONFIG_GPS_CONTROL_FIX_CHECK_INTERVAL=120
    CONFIG_GPS_CONTROL_FIX_TRY_TIME=360
    CONFIG_GPS_CONTROL_PSM_DISABLE_ON_STOP=n
    
    CONFIG_NORDIC_SECURITY_BACKEND=y

    So maybe 1.8V is enabled on that pin due to some of these options but it seems odd that these would be necessary.

  • I also tried adding all the rest of the prj.conf options, even if I didn't need them and still no 1.8V.  So it's got to be something else I guess.

  • Could you test with the at_client sample, and check what AT%XSIM? returns ?

    Do you get any errors code?

    Also check that the SIM-card is inserted correctly in the SIM socket. Some sockets allows the SIM-card to be inserted 2 different ways, but only one way works. And then you need to take the SIM-card out, turn it 180 degrees, and put it back in the socket again.

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