Crash when writing > 20 bytes (from Android)

[Roger Clark]

Hi,

I'm trying to write more than 20 bytes to a custom characteristic, from Android (Cordova BLE Central), but this completely crashes my App

APP_ERROR:ERROR:Fatal

I'm using SDK 12.1 App Template, plus the LED & Button example service LBS

I set the LED (Write) characteristic to have a max size of 256 like this

   attr_md.vloc       = BLE_GATTS_VLOC_STACK;
    attr_md.rd_auth    = 0;
    attr_md.wr_auth    = 0;
    attr_md.vlen       = 0;// variable length set to false (disabled)
    
    memset(&attr_char_value, 0, sizeof(attr_char_value));

    attr_char_value.p_uuid       = &ble_uuid;
    attr_char_value.p_attr_md    = &attr_md;
    attr_char_value.init_len     = sizeof(uint8_t);
    attr_char_value.init_offs    = 0;
    attr_char_value.max_len      = 256;//sizeof(uint16_t);
    attr_char_value.p_value      = NULL;

Do I need to increase some buffer size so I can send more than 20 bytes.

BTW. I am using the nRF51822QFAA (16k) and have the IRAM setting at 0x20001FE8

But perhaps I need to give the SD more RAM ??

[SRA]

You know the MTU on your device may be limited to 20 bytes right?

[run_ar]

If you are using the default ATT MTU size, maybe you should take a brief look at this thread and maybe also this.

[Roger Clark]

Thanks guys

I know that the max data transfer size is 20 byes, but I didnt expect the Application to have a fatal error if someone attempts to send more than 20 bytes.

I'd expect the SD to just reject the write, or truncate the data.

Crashing is a problem for me, as I keep some history data in RAM and it will be lost if the application cashes. (Writing data to Flash is not really an option as it would wear the flash out as it has limited write cycles

Perhaps this is a bug in the S130 SD V2,0

However its a bit of a pain to have to rebuild the same app for S130 SD V1.0 (even though its just an app for testing the connection to Android (Cordova)

Edit I guess I need to retest this on a non-custom service, that has a Write characteristic

[run_ar]

I'm sorry, I might have misunderstood your question. I thought you meant that the cordova ble central crashed. But I guess you are saying that the app on the nRF51 crashes when you try to do a long write from cordova? What happens if you set the init length = max length?

[syntroniks]

You may need to handle BLE_EVT_USER_MEM_REQUEST and BLE_EVT_USER_MEM_RELEASE like here github.com/.../ble_app_hrs---LongWrite