This project demonstrates the operation of a MIDI interface's hardware and provides a few straightforward examples of how the controller might be applied to MIDI systems. We'll begin by going through the specifics of the hardware interface. The MIDI protocol will then be examined, and we'll see how easy it is to create original software for this MIDI controller.
The MIDI connections can be constructed with just a few components. There are only a few resistors, a diode, and a tiny 8 pin IC required. The system's controller is a 2051 microcontroller, which is an expanded version of the well-known 8051 with 20 pins. The 2051's serial port (pins 2 and 3) is where the MIDI interface is connected. In addition, the 2051 contains an oscillator circuit with a 24 MHz crystal and two 33 pF capacitors, as well as a reset circuit with a 10 uF capacitor and an 8.2k resistor. The only component not visible is the 5 volt power source, which generates Vcc (5 Volts DC) for the circuit and is necessary to understand more about the 2051. The kit comes with an LM7805 and a 220 uF capacitor to convert a 9–12 VDC source to 5 VDC.
The 6N137 separation between two electrical systems. The MIDI-connected devices are not electrically connected to one another. The internal LED, which is wired between pins 2 and 3, emits light to a light-detecting diode when a current passes through it. The inbuilt transistor pulls the output at pin 6 low, activating the diode. The Output floats if there is no current flowing. In order to slightly pull the voltage at the output to 5 volts while the circuit is not in use, we attach an 8.2k resistor to pin 6 as opposed to letting it float.
By adjusting the voltage at pin 3 of the microcontroller, the microcontroller transmits signals via the MIDI connection. The 5 volts (Vcc) attached to pin 4 of the MIDI Out port provides the current. The following circuit is established when the MIDI Out port is linked to a MIDI In port on another system.
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