norns-hid-to-midi.lua

-- based on @okyeron's hid_demo/hid-events.lua
-- check MIDI Devices list printed below to REPL for which port to choose

-- change these to suit your needs
local midi_port_id = 1 -- especially this one
local midi_channel = 1 -- and probably this one
local midi_velocity = 100

function init()
    --  print some device data to REPL
    print("-------------")
    print("HID Devices:")
    for v in pairs(hid.devices) do
        print (v .. ": " .. hid.devices[v].name)
    end 
    print("-------------")
    print("MIDI Devices:")
    for v in pairs(midi.devices) do
        print (v .. ": " .. midi.devices[v].name)
    end 
    print("-------------")
end

local keyb = hid.connect()
local midi_out = midi.devices[midi_port_id]

function keyb.event(_, code, val)
    -- clamp to reasonable value
    local note = math.max(0, math.min(code, 127))
    
    -- key down = note on
    -- key up = note off
    local midi_type = (val == 1) and 'note_on' or 'note_off'
    
    print(midi_type..' ', note)
    
    -- selecting method dynamically
    -- so explicit MIDI port needed as first argument
    midi[midi_type](midi_out, note, midi_velocity, midi_channel)
end