MATLAB Examples

Troubleshooting Connection Issues with Sphero


Sphero does not show up in the list of available devices OR Connection error: using icinterface/fopen (line 83)

Sphero is not listed under available devices when creating the sphero object, or the following error is received:

sph = sphero
Error using sphero (line 498)
Unable to connect to device. Please check that the
device name is correct and the device is
Caused by:
     Error using icinterface/fopen (line 83)
     Unsuccessful open: Cannot connect to the device.
     Possible reasons are another application is
     connected or the device is not available.

This might happen after a failed attempt to either create a new sphero object or connect to an existing one, and it might be due to several reasons, such as the device name not being correct, or the device having a different name or being undiscoverable, out of range, or not awake.

To solve this, especially when creating a new sphero object, make sure that the device name is correct (for example Sphero-RGW for a sphero blinking Red, Green and White). Also, make sure that the sphero is paired to your computer, is awake and not currently connected to another device (it must be blinking with a sequence of 3 colors, see the related section in the readme.txt file for more about this, and the procedure to follow the very first time you use the sphero with MATLAB. You can also refer to the page on Getting Started with Sphero Connectivity Package).

If the above conditions are verified, then trying to create the Sphero object again (perhaps a couple of times) will usually result in a successful connection.

If you are still unable to connect to the device, close MATLAB, unpair (or remove) the device from the computer and then pair it again, restart MATLAB, and try creating a new sphero object.

If the problem persists, try updating the Sphero firmware by connecting to the Sphero app on an Android or iOS device, and repeat the above procedures.

Connection error: Undefined function 'Bluetooth'

Error using sphero (line 498)
Unable to connect to device. Please check that the device
name is correct and the device is discoverable
Caused by:
   	Undefined function 'instrhwinfo' for input arguments of type 'char'.

This error (undefined function 'instrhwinfo' or 'Bluetooth' ...) means that the Instrument Control Toolbox (ICT) is not installed. This package is based on the bluetooth connectivity functions provided by the the ICT, and so therefore you will need to get that toolbox if you want to use this package.

Sphero disconnected without any warning sign

If you notice that the sphero is disconnected but you have not received any error or disconnection message, it means that MATLAB is unaware that the connection got lost. This is unusual because any following command would be unsuccessful, therefore causing a disconnection.

In any case you can use the "disconnect" command before reconnecting (with the "connect" command).

Resetting the Sphero

Sometimes MATLAB loses the connection but the sphero is unaware of it, (that is it still displays a solid color without blinking). This might happen for example when the sphero variable is inadvertedly cleared while the sphero was still connected.

In such cases, you need to reset the sphero, which can be done by placing it on the charger.

If the sphero is still running (rotating) then the inductive copper coil under of the robotic chassis does not point straight down but at an angle of approximately 45 degrees between the vertical axes and the axis opposite to the direction of motion. Therefore, the charger must be placed at the same angle so that it is close to the Sphero inductive coil. Alternatively if you move the charger around the Sphero circumference it will find the coil and reset itself.

Also see this:

Once the sphero has been reset, then the connect command can be used to reinstate the connection to the sphero.

Warning received when connecting to device

Creating a connection to Sphero device produces the following warning, and the Status of the connection is 'closed':

sph = sphero('Sphero-GPG');
Warning: Error occured when reading Asynchronous message: Received response is not valid
Warning: The BytesAvailableFcn is being disabled. To enable the callback property
either connect to the hardware with FOPEN or set the BytesAvailableFcn property.
> In BluetoothApi>BluetoothApi.readResponse at 1145
 In sphero>sphero.get.Color at 1366

This might occur when the Sphero responds with an invalid response when trying to connect to it initially. Please try connecting to it once again.

If the problem persists, reset the Sphero device by placing it on the charger (see the section above on Resetting the Sphero), and then try to connect to it again.

Error when connection gets broken

The two errors and the warning shown below might occur when the connection gets lost. This can happen for a variety of reasons, such as the sphero going out of range, or running out of battery, or going to sleep because of inactivity.

In such cases, just wake up the sphero, make sure it's in range, and reconnect it using the "connect" command (or recreate the sphero variable).

Error using icinterface/fwrite (line 193)
An error occurred during writing
Error in sphero.internal.BluetoothApi/sendCmd (line 1251)
                fwrite(obj.Bt, cmd);
Error in sphero/set.Color (line 1354)
           [responseexpected, seq] = sendCmd(obj.Api, 'setrgbled', [], [], [], uint8(rgb),
Error using sphero.internal.BluetoothApi/readResponse
(line 1133)
Response Timeout
Error in sphero/heading (line 351)
   response = readResponse(obj.Api,
   responseexpected, seq,
Error in sphero/calibrate (line 1112)
   result2 = heading(obj, 0);
Warning: Unable to write to device. The Sphero might already be
> In sphero/BluetoothApi/sendCmd (line 1255)
  In sphero/set.Color (line 1354)

Error in sphero/readLocator (line 1068)

Error using sphero/BluetoothApi/readResponse (line 1133)
Unknown command ID received. Please check API definition
Error in sphero/readLocator (line 1068)
           response = readResponse(obj.Api,
           responseexpected, seq, obj.ResponseTimeout);

The most likely cause of this error is that you are using a Sphero with firmware version 3.71, in which this functionality was temporarily removed. Therefore, if you need to use the readLocator function you need to use either an older or newer version of the firmware.

If "sph" is the name of your Sphero object in the MATLAB workspace, then you can use the following commands to display the firmware version:

hw = hardwareinfo(sph);sphver = version(hw);
firmware = [num2str(sphver.MainSpheroApplicationVersion) ...
'.' num2str(sphver.MainSpheroApplicationRev)]

See Also

Sphero Connectivity Package Examples

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