technical description of the project PIC 16F877 to Midi
 
- page last update octobre 2006 -(página en castellano)
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Description of the circuit

  • The 8 analogical inputs ADC's (analog to digital converters) of the PIC 16F877 catch voltages from 4,8mV to 5V simultaneously (from the 8 envelope followers) and convert the signals to MIDI messages: NoteOn (<4,8mV), NoteOff (>4,8mV), NoteValue, Velocity, MIDI Channels or Voltage to frequency.
  • The 16 digital inputs, PortB and PortC of the PIC, are all programmed to convert the 5V trigger impulses from the pannel to MIDI messages. (see table 1 & table 2 page 16F877)
  • The PortD is used for 5LED's that indicate the state of the program and to send trigger impulses to synchronize the "7_digit_dispay". The 7digit displays shows the channel number.
  • The 8 inputs are independently programmable: MidiChannel, NoteValue, Prg.Change etc.
  • The top left hand pad switches the remaining 15 pads between level 0 and level 1. The switching is indicated by a red LED on the Controller Unit. In order to maintain the constant functioning of the Program Change Messages and the Audio Channel switching (the lowest 4 pad), the functions of these pads are duplicated on level 0 and level 1.
  • Striking the trigger pad “STORE, RC1”, on level 0 stores all values in operation.
  • Striking the trigger pad “NoteOff, RC2” in the “MENU-mode ”, recovers all initial values. (see table 3)
  • The Controller Unit incorporates 8 preamplifiers for the audio inputs. These preamplifiers are independent of those of the circuit to trigger the PIC 16F877.