-- @param pulse length in seconds
local pulseLength = 0.5

-- @param clock speed in seconds
local clockSpeed = 2

-- @param pulse direction
local pulseSide = "right"
local inputSide = "front"

-- @param redstone signal to disable clock
-- true = redstone turns on
-- false = redstone turns off
-- nil = ignore redstone
local redstone = nil

while true do
  term.clear()
  term.setCursorPos(1,1)

  print("Clock running, output " .. pulseSide .. "...")
  print(string.format("PULSE %.1fs / CLOCK %.1fs", pulseLength, clockSpeed))

  -- use redstone signal to determine if the clock is on or off
  while redstone ~= rs.getInput(inputSide) do
    rs.setOutput(pulseSide, true)
    sleep(pulseLength)

    rs.setOutput(pulseSide, false)
    sleep(clockSpeed - pulseLength)
  end

  -- if we dropped out of the clock loop, wait for redstone
  print("OFF (Waiting for redstone)")
  event = os.pullEvent("redstone")
end