Returns a GDB T response string.  This includes:
            The signal encountered.
            The current value of the important registers (sp, lr, pc).

def get_t_response(self, forceSignal=None):
        """
        Returns a GDB T response string.  This includes:
            The signal encountered.
            The current value of the important registers (sp, lr, pc).
        """
        if forceSignal is not None:
            response = six.b('T' + conversion.byte_to_hex2(forceSignal))
        else:
            response = six.b('T' + conversion.byte_to_hex2(self.get_signal_value()))

        # Append fp(r7), sp(r13), lr(r14), pc(r15)
        response += self.get_reg_index_value_pairs([7, 13, 14, 15])

        return response