Need information about GNSS Module, data sheet and configuration details



  • Hi,

    I am from India. I am working on GNSS module. I am facing issue related to GNSS module. I could able to connect GPS and getting GPS coordinate. But it takes nearly 40 sec to get the first GPS coordinate for all the HOT, WARM and COLD start conditions. I am facing the following issues,

    1. At present CXD56_GNSS_STMOD_HOT, CXD56_GNSS_STMOD_WARM and CXD56_GNSS_STMOD_COLD all are taking more than 40sec to fetch GPS data.
      As per the Spresense document, CXD56_GNSS_STMOD_HOT supposes to take nearly 1 sec and CXD56_GNSS_STMOD_WARM supposes to take nearly 20sec to get GPS data. But, I have not seen any such improvement as yet. By the way, the backup file CONFIG_CXD56_GNSS_BACKUP_FILENAME, /mnt/spif/gnss_backup.bin, is available. And the file is getting updated whenever appropriate GPS coordinate available.
      It is required to set current location for CXD56_GNSS_STMOD_HOT and CXD56_GNSS_STMOD_WARM. The current coordinate may be available in Backup file. But, not sure if the data available in Backup file are getting used or not during GNSS start. There is no information about format of the data in the backup file. So, could not read the Backup file also.

    nsh> ls /mnt/spif
    /mnt/spif:
    gnss_backup.bin
    nsh> cat /mnt/spif/gnss_backup.bin
    ¨#J½emÕ3
    C@ù<þ¥tëÐ
    8C
    ^c£B±Ô3
    ûwB}60¡B}6q¼BöI6BvV6ÏÝB±Ô3
    X¤B±Ô3
    âTöI6*]û B±Ô3
    ………………..

    1. Saw the followings in the file spresense/sdk/bsp/include/arch/chip/gnss.h,
      CXD56_GNSS_STMOD_WARM_ACC2
      CXD56_GNSS_STMOD_HOT_ACC
      CXD56_GNSS_STMOD_HOT_ACC2
      CXD56_GNSS_STMOD_HOT_ACC3
      But, there is no information how to use them.

    2. Not sure about purpose of the file CONFIG_CXD56_GNSS_CEP_FILENAME("/mnt/sd0/gnss_cep.bin").
      Looks like, the file supposes to be used for Circular Error Probable. But, no further information available about format of the file. No information available about, how to update the file.

    I need to understand Behavior of the GPS device,
    a. How the device is using current location to fetch GPS location for CXD56_GNSS_STMOD_HOT and CXD56_GNSS_STMOD_WARM.
    b. What is the behavior of the GPS device if current location not provided for CXD56_GNSS_STMOD_HOT and CXD56_GNSS_STMOD_WARM.
    c. What is the optimal configuration of the GPS device to get the most accurate GPS coordinate,
    d. How to use or update the files CONFIG_CXD56_GNSS_CEP_FILENAME and CONFIG_CXD56_GNSS_BACKUP_FILENAME.

    Kindly let me know, how to obtain GPS datasheet for the spresense board and document to configure the board.

    Thanks and regards,
    Amit