memset (cb->send_buffer, 0, sizeof (cb->send_buffer));
cb->send_buffer_free = sizeof (cb->send_buffer);
cb->send_buffer_fill = 0;
memset (cb->send_buffer, 0, sizeof (cb->send_buffer));
cb->send_buffer_free = sizeof (cb->send_buffer);
cb->send_buffer_fill = 0;