RE: bt_gatt_read only reads 22 bytes from BLE characteristic, while it should return 240 bytes

Dirk_ — Tue, 18 Apr 2023 13:59:08 GMT

Thank you. This did the trick for me.

The BT_GATT_ITER_CONTINUE return value is indeed mentioned in the callback function documentation.

Somehow I overlooked that.

The new output adds up to the 240 bytes as expected. 😁

RE: bt_gatt_read only reads 22 bytes from BLE characteristic, while it should return 240 bytes

pirun lee — Tue, 18 Apr 2023 13:46:29 GMT

You need Increase MTU or GATT long read procedure.

uint16_t offset = 0;
static uint8_t read_cb(struct bt_conn *conn, uint8_t err,
				    struct bt_gatt_read_params *params,
				    const void *data, uint16_t length)
{
    printk("Read data of length %d\n", length);

	if (err)
	{
		printk("Read Err %d\n", err);
	}


    if (data != NULL) {
        offset += length;
	    // << process data here >>
   		return BT_GATT_ITER_CONTINUE;
    } else {
        // The end of long read procedure
    		return BT_GATT_ITER_STOP;
    }
}