Maximum bytes sent in a characteristic indicate function

[JPSvanderWalt]

Hi, I need to send data larger than 16 bytes on a characteristic.  I see that the maximum number of bytes I can send using the indicate function is limited to 16 bytes.

static uint8_t sm[16];

ind_params.attr = &vnd_svc.attrs[2];
		ind_params.func = indicate_cb;
		ind_params.data = &sm;
		ind_params.len = sizeof(sm);

		if (bt_gatt_indicate(NULL, &ind_params) == 0) {
			indicating = 2U;
		}

Ideally, I need sm[] to be between 32 bytes and 64 bytes.  Is there a way to increase this size or do I have to send multiple 16-byte packets?  I am developing using Zephyr.  Your help is highly appreciated.

[Hung Bui]

Hi, 

To get a high throughput you should try to achieve the maximum ATT_MTU and longest data length extension CONFIG_BT_CTLR_DATA_LENGTH_MAX (usually set = ATT_MTU+4) . 

If the size is still smaller than the amount of data you want to send, you would need to segment it to multiple trunks and send one by one.