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CC3235MODAS: LAUNCHCC3235MOD transceiver mode

Part Number: CC3235MODAS
Other Parts Discussed in Thread: CC3235MODS

I'm using cc3235MODS module for L2 level N:N communications in transceiver mode.
I have three issues:

The customer site is using 5GHz channels higher than 177. When I set rf channel like 178, the image
doesn't produce any error, but when I run this image on my target board, it puts out the following
error message:
[ERROR] - FATAL ERROR: Async event timeout detected [event opcode =0x100a]
Instead, when I run the image with channel number less than 166 and change the channel to a larger one
by command, it seems to be working. Is this a workaround?

I followed transceiver section (Chapter 13) of "SimpleLink WiFi CC3x20, CC3x3x Network Proceesor User's
I'm using the following functions provided:
- sl_Socket()
- sl_Send()
- sl_Recv()
- sl_Close()
I tried every rf rate parameters given in the "network_terminal_CC3232S_LAUNCHXL_tirtos_ccs" project.
How can I modify bandwidth? I guess default bandwidth is 20MHz, I want to increase it to 40MHz or
larger ones.

According to the User's Guide as mentioned, at Transceiver Socket, it says that with a transceiver socket,
the user can choose to use only low rates. What's the maximum rates then? The sample codes
SL_WLAN_MAX_NUM_RATES} Can I use all of these? What's the number of SL_WLAN_MAX_NUM_RATES?

Any comments will be highly appreciated.

J.Y. Kim

  • Hi Kim,

    What Service Pack are used at both devices? What country code is set at both devices?

    CC3235 devices supports 20MHz channel only. You cannot use 40MHz channels.

    I am not sure what exact SL_WLAN_RATE_ parameters are supported at transceiver mode. But I suppose all described at enum SlWlanRateIndex_e. I am not sure about meaning of SL_WLAN_MAX_NUM_RATES (=0xFF). Please wait for answer from others.


  • CC3235 only supports 20MHz.

    Maximum rate is MCS_7 (you can find information on the rates in the internet).

    I'm not sure what did you mean by changing the channel by command. Please provide the code or explain this.


  • Thanks for the comments.


  • Thanks for the comments.

    Now I understand that bandwidth is 20MHz only.

    As for changing channel, I implemented AT command like [AT+RATE=<N>] which calls

    NumOfBytes = sl_Send(i32Soc,buff,sizeof(buff),SL_WLAN_RAW_RF_TX_PARAMS(rfchannel,rfrate,rftxpower,rfpreamble));

    where I changed rfchannel

    I have one more question.

    One of the goals of this project is to get communication success ratio > 90% when 10 devices randomly
    transmit a 60 byte data in broadcast every 50 ms. i.e., 10:10 broadcast or 10 L2 data in 50ms.
    Currently, it is less than 80% at 5:5 broadcast.

    How can I increase the performance? I'm using the following parameters:


    - UART: 3M baud 

    - sl_Recv() in non blocking mode

    I tried most combinations except RX filtering.

    Do you think I already reach the limit? Or there might be any chance to improve it.

    J.Y. Kim

  • are you checking in a controlled environment (rf chamber) or in open air?

    There are many factors (interferers) that may reduce the success ratio.

    You can try the options in the sl_SetSockOpt (specifically the SL_SO_PHY_TX_... options, e.g. the CCA behavior) to optimize the results.