Firmware-72 Operation

The USB-microDig is powered by USB, communicates through a virtual serial port using the MIDI message protocol, and can operate in host mode or stand-alone mode. Host mode is intended for using the USB-microDig with a computer that processes the sensor data and/or controls the actuator outputs, while stand-alone mode is intended for using the USB-microDig either on its own, where sensor data is mapped to actuator outputs, or together with other MIDI capable devices.

To set the USB-microDig mode, use the SET MODE command.

Power

The USB-microDig is powered by USB and provides 5V power to the connected sensors/actuators. It is registered as a device that uses 300mA, so if the maximum allowed current has been exceeded for the USB hub where the USB-microDig is connected you might get a system message on your computer warning you about this or the hub will simply shut the power off. In this case you will need to get a powered hub so that it can provide sufficient current to the USB-microDig. The USB-microDig is compliant with the USB v2.0 specification and uses the full-speed (12Mbps) transfer rate.

Communication

To communicate with the USB-microDig you need to connect its USB cable to your computer and install the supplied driver available for download from our web site (Windows or MacOS). You can then establish a connection with the USB-microDig by using our free Connect or BlueMIDI application or use the virtual COM port (VCP) with your own application (such as the serial object in Max/MSP). If you are using the VCP the COM port setting of the USB-microDig is 115200 bps, no parity, 1 stop bit, 8 data bits, hardware data flow control enabled.

Flow Control

In host mode the USB-microDig can detect when the COM port is open by the use of hardware data flow control (using the RTS and CTS pins of the COM port, see also the COM command below). If the software application you are using doesn’t have hardware data flow control (such as the Max/MSP serial object) then the COM port can be open but the USB-microDig pauses data processing and the IN and OUT LED on the USB-microDig will keep on flashing once a second until it receives a byte (that your software application sent). Once a byte has been received data processing resumes and the IN and OUT LED will only be ON momentarily once every second when data is transmitted as per their definition above, even after the COM port is closed.

If the software application uses hardware data flow control, and the USB-microDig is in host mode, when the USB-microDig COM port is closed (by default when the USB-microDig is being connected) the USB-microDig pauses data processing and the IN and OUT LED will blink again once every second.

When the USB-microDig is in stand-alone mode data processing is never paused, it ignores data flow control and the IN and OUT LED will not blink once a second but only when data is transmitted.

Protocol

In this documentation the communication protocol used by the USB-microDig is based on the MIDI protocol. Despite the fact that the USB-microDig has a different baud rate, uses a serial port and has no MIDI cables, you can use it as a MIDI device by running our free serial port to MIDI bridging software that makes the serial port data available at a MIDI port on the computer. This way you can use any MIDI application to communicate with the USB-microDig. The “MIDI input” and “MIDI output” expressions used in this document therefore refer to a communication setup as established between the USB-microDig and the computer running our serial-MIDI bridging software. You can turn it into a stand-alone MIDI (output-only) device by using our USB-microMIDICable.