USB Bell Rings In Custom Terminal

Old TeleTypes and even typewriters had bells. Real bells. So that ASCII BEL character is supposed to make an honest to goodness ringing sound. While some modern terminals make a beep from the computer speakers, it isn’t the same. [Tenderlove] must agree, because the turned a Microchip USB to I2C bridge chip into a HID-controlled bell.

The only problem we see is that you have to have a patch to your terminal to ring the bell. We’d love to see some filter for TCP or serial that would catch BEL characters, but on the plus side, it is easy to ring the bell from any sort of application since it responds to normal HID commands.

If a bell doesn’t strike your fancy, you could use the same technique to easily add a digital output for anything. Of course, you could also use the MCP2221A as intended and put an I2C bus out there with a digital I/O expander or any number of other I2C chips.

Despite the video’s infomercial attitude, you can’t actually buy the bell. You’ll have to make it. It wouldn’t be very hard to duplicate with an Arduino or anything else you can connect to a PC as long as you modify the driving software accordingly.

We know you can play a sound file of a bell, but sometimes a real bell is just necessary. If you want to ring big bells, turns out there is an entire cult of wanna be Quasimodos.

13 thoughts on “USB Bell Rings In Custom Terminal

    1. Made me giggle.

      I don’t have those problems anymore, however. I use a paint pen or permanent marker to mark every cable and every adapter with an arrow on the “top” side and and “X” on the “bottom” side of the plug or socket. It’s no longer a 50/50 guess.

    2. Not quite, USB works this way…
      1. Try it, it doesn’t seem to fit.
      2. Turn it over and try again, it still doesn’t fit.
      3. Turn it back again, this time it fits! Scratch head wondering why if you had it the right way up the first time, why didn’t it fit the first time!

  1. This should include a small slip of paper so that critical information isn’t recognized at a critical juncture.

    (Both “Fail Safe” and later “The Andromeda Strain” describe a slip of paper getting between the bell and the clapper, silencing it just as critical information is received in order to increase dramatic tension.)

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