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CC1310: SF_TI_SYNC_PIN for OMS in wmbus_cc13x0_rtos_2_0_0

Part Number: CC1310
Other Parts Discussed in Thread: WMBUS,

My customer is developing a WMBUS meter with CC1310 and has a question about the SF_TI_SYNC_PIN in the WMBUS example: is the synchronous data transmission compulsory or optional for OMS certification? In other words, is SF_TI_SYNC_PIN compulsory for an OMS meter? The customer need to confirm this to finalize the hardware design.

Thanks.

Best regrads,

Shuyang

  • Hi Shuyang,

    Here is the answer I received:

    "

    Synchronous data transmission is compulsory for OMS certification. In this case, I am referring to the OMS Conformance Test. The synchronous data transmission is, in other words, transmitting data frame periodically according to the defined interval value. The interval time between each transmission must be accurate in order to pass the certification; therefore, the timing is handled by the stack.

     

    The ‘SF_TI_SYNC_PIN’ then is a useful feature for this use case. The host will be notified by an external pin (by default is DIO11) some seconds before the synchronous transmission starts. This gives an opportunity for the host to update the data content beforehand.

    "

    Regards,

    Arthur

  • Hi Arthur,

    Thanks for clarifying. I will notice the customer and add this pin in their design.

    Best regards,

    Shuyang

  • Hi Arthur,

    Customer has a follow-up question about the synchronous transmission: in serial mode, the meter example will send a SATP_ID_APL_MTR_INDICATION_PREPARE_UD (A5 00 07 FF F8 01 06 04 00 00 03 E8 E7 A3) command through UART before sending a packet, and send a SATP_APL_INDICATION_GEN (A5 00 04 FF FB 01 03 02 00 03 81 A5 00 04 FF FB 01 06 02 01 0A 49) command after each packet. 

    Are these commands also mandatory for OMS comfomance?

    Best regards,

    Shuyang

  • Hi Shuyang,

    I got the following answer:

    "

    The SATP_ID_APL_MTR_INDICATION_PREPARE_UD command via UART has the same purpose as ‘SF_TI_SYNC_PIN’ in the previous mail. It notifies the host controller before synchronous packet is sent, so the host controller may update the data content if required.

    So, it’s a useful feature on field applications. But for OMS conformance test, as far as I know, I do not think that there is any test case that expects the data content to be changed during test.

     

    The OMS conformance test just expects the data content to be correct, and the synchronous timing to be accurate.

     

    You might wonder why there are two kinds/ways of notifications before synchronous packet is sent. The SATP_ID_APL_MTR_INDICATION_PREPARE_UD is the default notification that our stack provides. The ‘SF_TI_SYNC_PIN’ is an extra feature requested to be implemented by TI in the past.

    "


    Regards,

    Arthur

  • Hi Arthur,

    Thanks for the answer. If my understanding is correct, one can use either SATP_ID_APL_MTR_INDICATION_PREPARE_UD command or SF_TI_SYNC_PIN to notify the host? How can I remove the SATP_ID_APL_MTR_INDICATION_PREPARE_UD command if I want to? Right now all the commands are wrapped into the wmbus_serial_apl_mtr_run function and I can't see the source code.

    Best regards,

    Shuyang

  • Hi Shuyang,

    Why do they want to remove that command? Morever, they would need access to the stack source to remove that command.

    Regards,

    Arthur

  • Hi Arthur,

    They want this to save more power becasue UART will consume more power than toggling a GPIO.

    Are you saying it is not possible with the current WMBUS SDK? To my understanding the stack source is not open to customer, is that correct?

    Best regards,

    Shuyang

  • Hi Authur,

    Any update for the latest question? Thanks.

    Best regards,

    Shuyang

  • Hi Shuyang,

    It is indeed not possible to remove specific serial commands without access to the stack source code.

    As of the power savings concerns, I got the following answer:

    "

    Speaking of saving power or going to low power mode. There is already a feature for this purpose, that is “SHUTDOWN_SLEEP_PIN”. This feature is described alongside with the ‘SF_TI_SYNC_PIN’ in the “Features implemented for Texas Instruments” documentation.

    In brief, the host controller can select the low power mode of CC1310 to either Sleep mode or Shutdown mode via SERIAL_CMD_MTR_SET_POWER_MODE command and control the state of CC1310 aka. set to low power mode by the pin.

     

    In case when Shutdown mode is selected and the SHUTDOWN_SLEEP_PIN is pulled down to 0V, the device will consume very small power (~1us) and UART is not activated.

     "

     Regards,

    Arthur

  • Hi Arthur,

    Thanks for the reply. The customer tried SHUTDOWN_SLEEP_PIN and found that the CC1310 meter still sends WMBUS data, but the UART commands SATP_ID_APL_MTR_INDICATION_PREPARE_UD and SATP_ID_APL_MTR_INDICATION_GEN are gone.

    Is that expected behavior of the stack?

    Best regards,

    Shuyang

  • Hi Shuyang,

    According to the documentation, this is expected behavior:

    "Please note that the uart interface will be disabled in both low power modes (sleep mode and shutdown mode). "

    Regards,

    Arthur