DA14683: RF Master - Set TX Power During Tests?


Custom DA14683 Board

Newest SDK = (last updated in 2018)


This is really a continuation of this issue: https://community.renesas.com/wireles-connectivity/f/bluetooth-low-energy/28975/da14683-fcc-part-15-testing-setup-and-rf-functionality/99343#99343

In the sdk, there is a function to set the TX Power that takes a value from an enum.  Both shown here:

void hw_rf_set_tx_power_ble(HW_RF_PWR_LUT_SETTING lut)
    RFCU->RF_TX_PWR_BLE_REG = lut;
    rf_tx_power_luts.tx_power_ble = lut;

typedef enum {
        HW_RF_PWR_LUT_0dbm = 0,   /**< TX PWR attenuation 0 dbm */
        HW_RF_PWR_LUT_m1dbm = 1,  /**< TX PWR attenuation -1 dbm */
        HW_RF_PWR_LUT_m2dbm = 2,  /**< TX PWR attenuation -2 dbm */
        HW_RF_PWR_LUT_m3dbm = 3,  /**< TX PWR attenuation -3 dbm */
        HW_RF_PWR_LUT_m4dbm = 4,  /**< TX PWR attenuation -4 dbm */

As noted in this issue: community.renesas.com/.../da14683-at-what-point-during-power-up-is-the-ble-tx-power-level-set

"The hw_rf_set_tx_power_ble() is changing the TX power attenuation setting."

Ok.  So using that I should be able to set the TX power in my program.

.... but there appears to be no such option for setting the TX power in the SmartSnippets ToolBox RF Master.

If I'm using the PLT_FW and SmartSnippets Toolbox RF Master during FCC testing, how do I set the TX power level there to match what my program will be doing when it's running my firmware?

If the RF Master from the toolbox uses a higher TX power than my program does, then I could fail the FCC testing even through my program would be within limits.  


1) How do you set the TX power levels in the SmartSnippets Toolbox RF Master for the DA14683?


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  • This is an unacceptable answer.

    First you insist I use the RF Master to control the radio over the UART.  Now you tell me that there is no way to set the radio TX Power Attenuator through the RF Master?  

    How am I supposed to pass the lower allowable power FCC testing when I can't set the TX Power Attenuator to the required lower power level during the direct tests?

    Paging Ben Lauret... We need to talk about escalating this to level 2 support.... 

  • What is this?  I feel like I am on hold with an AT&T call center.

    Let me summarize your responses to this very specific question:

      a) "I'm going to play a word/semantics game and try to dodge your question."

      b) "You can't do the thing you want to do."

      c) "I'm going to be overly general and suggest some general links, which also happen to not answer the actual question."

    As I said before, not being able to set the TX Power ATTENUATOR in the tool that you require for FCC testing is a fundamental oversight.  Hopefully you realize that part of the FCC test is actually measuring the TX Output Power.  Your whole RF Master system is useless if it can't set the output power ATTENUATOR to match what the end application will be using.

    You can claim "it hasn't been a problem before" but the FCC rules changed this year and now have a significantly lower allowable power for wearable devices.  If you don't want to support this product line, just End-of-life or Not-For-New-Designs it already and move on.  That would have saved me a ton of trouble.

    Considering I don't think this is a problem with the actual DA14683 hardware, and all the relevant systems (DA14683, SS Toolbox, plt_fw) should be able to do the required functionality, It would be great if you could just escalate this to a senior support and we can get this resolved without any more games.  

  • Nathan, I have created an internal ticket for this. we are checking this and will get back to you.

  • HI ,

    We currently do not believe the DA14682/DA14683 is end of life or not recommended for new design. We encourage customers to keep on designing new product as we believe they can bring innovative product to the market with this family of microcontrollers.

    The reason why there is no API for setting the output power is that it's not a supported feature. Renesas does not suport running the device at any other transmission output than 0 dBm. Failure to do so expose your application to failure to comply with various regulatory requirements include FCC and bluetooth certification.

    The attenuator is only a convenience feature for internal RF testing and one could argue this is should not be exposed in public SDK. 

    With regards to FCC, our device is tested and certified under title 47 part 15 (unlicensed band). As far as we are aware, there is no changes in part 15 which impact the DA1468x nor any other smartbond family with regards to emissions emission. I searched in the part 15 documents and I can't find any mention specific for wearable devices in this section. if you have a specific requirement you or your test house want to share, please share with us and we will have a through look. 

    As you mentioned specific requirements for wearables, some do actually exist but under other part of the regulation, for instance Mobile phone under part 22. Our current understanding is devices operating under part 15 at 0 dBm are exempt from SAR testing. I could not get a confirmation from our test house, but we were not able to locate new SAR regulation which indication otherwise. If you have a different view please point us to the specific regulation you are concerned about and we'll share with our own test house and seek their opinion. 

  • Hey Ben,

    Thank you very much for directly addressing my questions.  I appreciate it.  

    The relevant FCC rules change is KDB 447498.  See www.agccert.com/.../646.html

    I talked with my testing lab again and he pointed out that while that rules change was scheduled to go into effect in April 2022, that they first postponed it until July, then again to some later date.  So while it may not be in effect now, it will be eventually.  From my understanding, under those new rules and without the TX ATTENUATOR the DA14683 would be close to if not exceeding the power limit for a wearable device close to the body  

    The testing of the present device looks like it will be able to use the old limits, but if I were to select the DA14683 as a platform for other devices moving forward and those devices needed to be tested under the new rules, then there could be issues there without some TX ATTENUATION.

    I find it interesting that you would not want to support a TX ATTENUATOR feature that is already built into the DA14683 and implemented in the SDK.  Hopefully you can reconsider given that feature may be necessary when the FCC stops postponing their rules changes.

    Thanks again.

  • Hi ,

    Thanks for the specific pointer. We're checking on this specific. As mentioned earlier, we have so far assumed application based on our devices were most likely exempt from SAR testing. 

    Do you have specific data on you application antenna gain? Our initial feeling is it's unlikely your application will be over 4.4 dBm.