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Migrating from TD1208(R) to TD1508

Posted: Fri Nov 04, 2016 9:30 am
by ramon2015

I have been reading posts related to the brand new TD1508 and I still have some general questions.

- In the TD1508 description says it has SPI bus available. I see you can have an USART via pins USR1-4. Is this supported by the SDK? which version?
- If I compile my current program working with TD1208 would I have some issue when compiling for TD1508. Would I need to call a different sigfox senidng functions? RF power configuration?
- How long does it take to send a FCC sigfox message?
- When designing dual band devices (FCC & ETSI)? the only choice is to assembly either TDF1208 or TD1508 for target region, right? I guess this is related to cercification reasons ?
- As read in other post if I use TD1508 I can use your FCC ID but you mention the recommendations described in the TD1508 should be followed, right? Then, since this is open to interpretation I would like to know which are the mandatory topics to be followed?
- FCC frequency range is 902 to 928 MHz for both TX and RX, right? or there is specific channels for TX and RX?
- Is the bitrate selectable by the user or it is fixed by SIGFOX?

Regards, Ramon.

Re: Migrating from TD1208(R) to TD1508

Posted: Mon Nov 28, 2016 1:40 pm
by mstempin
Hi Ramon,
  • Yes, the SPI bus is available, but there is no specific support in the SDK, you need to use the underlying emlib API and examples
  • No, the function to send a Sigfox frame is the same. For channel & power configuration, you will have to add a few lines of code, please check this reply. Also, because of current Sigfox network deployment, you will have to reset the module at least every 2 messages to been seen by the receiving antennas
  • For FCC, the modulation is @ 600 bps vs. 100 bps, so the messages takes 6x less time to transmit (~1 s). Donwlink timings are still the same, though
  • The TD1508 is designed for FCC compliance, with a +24 dBm output power, whereas the TD1208 is designed for ETSI compliance with +14 dBm output power. This difference requires a completely different chip configuration (external PA) that would prove quite inefficient for ETSI, thus the 2 different pin-to-pin-compatible modules
  • Yes, provided that you meet the requirement (no other RF in the same end product, same antenna, proper labeling), and that you follow the provided guidelines for power supply, PCB stack-up and trace characteristics. These guidelines are classic but detailed and state-of-the-art rules that you have to adapt and adjust (not interpret!) for your specific device
  • The TD1508 is designed to operate over the whole 902-928 MHz ISM band, even if the Sigfox is currently only using a subset of this band. The TD1508 is preset to work with the current Sigfox network channels, but you cannot make any assumption that they will not change in the future (keeping backward compatibility, of course)
  • The bitrate is fixed for the Sigfox protocol: 100 bps for ETSI, and 600 bps for FCC, but it is not user-selectable

I hope I answered all your relevant questions!

Re: Migrating from TD1208(R) to TD1508

Posted: Tue Nov 29, 2016 7:15 pm
by ramon2015

Thanks very much for your detailed answer. Some more questions:

    In order to set the POWER. This is the funciton for such purpose, but the TD1508 can go up to 24 dBm, right?

    bool TD_SIGFOX_RfPower ( uint8_t power )
    Configure the default RF power.
    [in] power The power level in dBm, between 0..14 for SI4461 and 0..20 for SI4463.

    You mention that we should reset the module every 2 messages sent, which is quite unexpected/undesired. I would like to know further details about this:
    - Is this a temporary or definitive workaround?
    - Is this due to the sequence number? I do not understand why the base stations cannot get more than 2 messages in a row.
    - Which is the effect of reseting the module?

    Regarding the FCC certification you say we have to use the same antenna, but I read in the info that we can use an antenna which shows a gain equal or low to your antenna, is this true or I have to use the very same antenna?
    If we add other RF in the device (e.g Bluetooh, wifi, ...) and this module does not operate (in terms of RF) simultaneously with the TD1508, is there a chance to use your FCC ID?

    The frequency channels are the same for Uplink and Downlink ? I would like to know which central frequency should I use when tuning my antenna.

    Regards, Ramon.

    Re: Migrating from TD1208(R) to TD1508

    Posted: Wed Dec 14, 2016 4:28 pm
    by mstempin
    The maximum power is controlled against the actual module type, so +24 dBm for the TD1508.

    Regarding the workaround, it is required based on the Sigfox network deployment, so I cannot say if it is temporary or not. This is not due to the sequence number.

    The effect of resetting the module is that the module will restart and all RAM will be erased, except for the stack area and Flash memory, of course.

    For the FCC part, there are some places where it is said that it must be the exact same one, some other places it must be equal or worse in terms of performance.

    You are not allowed to have other RF circuits in the end product, I don"t think that non simultaneous is seen as an acceptable exception. I think that you may have to rool our own certification as soon as you have more than a single RF in your end product, so you cannot use our FCC ID.

    No, the frequencies are centered on 902.8 MHz for uplink and 905.8 MHz for downlink, but you should accept to work in the whole 902-928 MHz band, even with a suboptimal matching.

    Re: Migrating from TD1208(R) to TD1508

    Posted: Sat Feb 25, 2017 1:39 pm
    by disk91
    Do we really need to reset the module every 2 transmissions ? I'm building app based on custom firmware so if I reset the module I lost all the context of my program. by-the-way I do not understand what it change to reset or not reset regarding the network communication, can you please clarify ?


    Re: Migrating from TD1208(R) to TD1508

    Posted: Mon Feb 27, 2017 9:26 am
    by dandavid3000

    As far as I know that Sigfox have some troubles with FCC rules. Their bases stations are able to receive the first 2 messages from the device.
    "FCC rules force the devices to operate on 50 micro channels of 25KHz. The 2 first messages (2*3 frames) are sent on the default macro channel, and the 16 following messages are sent on the 8 other 192KHz macro channels if nothing specific is done."
    That's why we need to reset the device in order to resend messages on the deault channel. You can use flash memory to prevent the loss of device reboot, but obviously we can't keep all of them. We just keep what is important.

    I also tried to use CFlash to flash the TD1508 firmware but I didn't know the exact ID like you. TDLoader didn't work neither. We have to wait for an answer from TD.
    I'm using Silabs EFM32TG-STK3300 board, and it's only way I can flash firmware on TD1508.

    disk91 wrote:Do we really need to reset the module every 2 transmissions ? I'm building app based on custom firmware so if I reset the module I lost all the context of my program. by-the-way I do not understand what it change to reset or not reset regarding the network communication, can you please clarify ?


    disk91 wrote:Please, what is the product ID to be used for flashing TD1508 ?
    ./cflash -d /dev/ttyUSB1 -b 115200 -p ??? ..

    Re: Migrating from TD1208(R) to TD1508

    Posted: Tue Feb 28, 2017 4:41 pm
    by disk91
    Is there a way to way to reset the sigfox module without reseting the entire software ? because in my application I just can't reset the device.

    Thanks for the cflash response waiting for a better one as in production I can't tell my end-user he needs to buy a Jlink loader for updating !

    I also have reboot on startup, I assume I could have some USRx mapping problem due to the new hardware. Does someone had a td_module.h file for TD1508 ?


    Re: Migrating from TD1208(R) to TD1508

    Posted: Sun Sep 17, 2017 5:03 pm
    by disk91
    A way to not reset the TD1508 after 2 emit (if you make your custom firmware) is to reset the channel variable in the
    .bss.Channel 0x20001788 0x2 C:\TD\TD_RF_Module_SDK-v6.0.0\Github\TD_RF_Module_SDK\lib\libtdrf\GCC Release EZR\libtdrf.a(td_sigfox_downlink.o)
    you can find this in the .map file
    then reset it before every transmission...