Starting lte data call using MC7455

Hi All

I have few question regarding MC7455.

Does MC7455 support mulitple PDN as supported by EM7565?

I have application that uses liteqmi api to bring up the data call on EM7565. Will the same software(steps) should work on MC7455?

What is different between EM7565 and MC7455 in term of starting lte data call?

If you have any pointers for MC7455 describing lte data call please point me to it.


Thank you

Hi @Dhruval
Yes, the 7455 supports multi PDN. You will have to check if multi RMNET is enabled via AT!USBCOMP command. For example:
at!usbcomp?
Config Index: 1
Config Type: 1 (Generic)
Interface bitmask: 0000050D (diag,nmea,modem,rmnet0,rmnet1)
OK
This supports 2 PDNs(rmnet0,rmnet1). The Sierra driver will create the relevant number of /dev/qcqmiX files and they will be used to start the different data connections. The “lite-connection-manager” uses the multi RMNET method for 7455.

The EM75xx, on the other hand, uses QMAP for multi PDN over one RMNET connection. Only one /dev/qcqmi device file will be created. The “lite-qmi-demo” supports QMAP over single RMNET via command line option “-v”. Please refer https://source.sierrawireless.com/resources/airprime/application_notes_and_code_samples/airprime---multiple-pdn-support-on-newer-sierra-wireless-modules/ for more informaito on QMAP.

Hi @ajoseph

Thank you for prompt reply. As you mentioned earlier about EM75XX functionality, I have a working application which uses lite sdk API and works fine.

Now I am trying to integrate MC74XX, do you have similarr app note(similar to app note shown above for EM75XX) or reference code/Demo app that works with EM74XX.


Thank you.

Hi @Dhruval

We do not have an application note for 7455 but since you have EM75 working :+1:, 7455 will be much more simple. The main diferrence is that you do not need to set the MUX ID to the modem and driver via pack_wds_SetMuxID() and ioctl(QMI_SET_QMAP_xx). This is because, with the 74xx, each PDNs has distinct host device files. With the EM75, all PDNs are muxed over one qcqmiX device file.

The 7455 will create a RMNET device file for each PDN. For example, for 2 PDNs, 7455 will create /dev/qcqmi0 and /dev/qcqmi1. Pseudo code for multi - PDN

PDN 1, IPv4

  1. wds_ipv4fd_pdn1 = open(/dev/qcqmi0)
  2. ioctl(wds_ipv4fd_pdn1, QMI_GET_SERVICE_FILE_IOCTL, eWDS)
  3. pack_wds_SLQSSetIPFamilyPreference(IPv4). write(wds_ipv4fd_pdn1 )
  4. pack_wds_SLQSStartDataSession(). write(wds_ipv4fd_pdn1 )
    PDN 2, IPv4
  5. wds_ipv4fd_pdn2 = open(/dev/qcqmi1)
  6. ioctl(wds_ipv4fd_pdn2, QMI_GET_SERVICE_FILE_IOCTL, eWDS)
  7. pack_wds_SLQSSetIPFamilyPreference(IPv4). write(wds_ipv4fd_pdn2 )
  8. pack_wds_SLQSStartDataSession(). write(wds_ipv4fd_pdn2 )

For IPv6 you would set the IP preference to IPv6 with 2 other FDs opened with the respective device file. You will then manage the FDs similar to EM75. Please refer “lite-connection-manager” for 74xx based data connection management.

The EM75(and WP76) can support multiple PDNs (we’ve tested upto 4) as QMAP can be handled in the host application. The 74xx modems can only support 2 PDNs as there is a USB interface limitation.

Hope the info is useful!

Thank you @ajoseph Got it working . Appreciate your help!!!

Glad to know :grinning: