Sustain pedal sends continuous MIDI values: how to test

You press and release your sustain pedal, but your MIDI monitor shows a stream of changing values instead of a simple on and off. That can be normal for a half-damper pedal, or it can point to a pedal mode, calibration, connection, or hardware problem.

Use the MIDI Test to see which messages arrive from your keyboard or controller. It can help you tell whether the pedal is sending continuous values, switching cleanly, or sending messages when you are not touching it. Safari does not support this test, so use a different browser.

Test the sustain pedal

1. Open the MIDI Test in a browser other than Safari. Connect your keyboard or MIDI controller, then allow MIDI access if the browser asks.
2. Select the connected MIDI device if the test does not show its messages automatically. Leave other MIDI controllers disconnected for now, so you can identify which device is sending each message.
3. Keep your foot off the pedal and watch the incoming messages. Note the controller number and value, if a message appears.
4. Press the pedal slowly, hold it, and release it. Repeat a few times, pausing between presses. Watch whether the same controller number changes gradually or jumps between low and high values.
5. Test the pedal again without touching it for several seconds. If values keep changing, gently check whether the pedal cable or plug is loose, then repeat the test.

Look at the controller number as well as the value. The sustain function normally uses MIDI Continuous Controller 64, often written as CC64. Another number may mean the pedal is assigned to expression, volume, or a custom function instead.

What the result means

CC64 moves through several values as you press

A gradual range can be expected if the pedal supports half-pedaling and the keyboard is set to send that data. Half-pedaling lets some instruments respond to how far the pedal is pressed, rather than treating it only as up or down. A simple switch pedal generally sends an off value and an on value instead.

For the standard sustain controller, values from 0 through 63 mean off, and values from 64 through 127 mean on. An instrument that supports half-pedaling may also use the values within that range to change the sustain effect. If your software only needs a basic switch, it may treat every value at 64 or above as pedal down.

The pedal sends a low value and a high value

This is the usual pattern for a switch-style sustain pedal. The exact values can vary, but they should settle near the low end when released and the high end when pressed. If the sound still sustains after release, check whether the keyboard and pedal agree on polarity and whether your music software is listening to the same device.

A different controller number changes

The pedal may be assigned to another MIDI function. For example, a pedal configured as an expression control can send a continuous range rather than the sustain on and off behavior you expected. Change the pedal assignment on the keyboard or in its control software to CC64 if you want it to control sustain.

Values change while the pedal is untouched

Unexpected messages can come from a loose plug, a worn pedal, a damaged cable, or another connected controller. Disconnect other MIDI devices and test again. If the changing messages stop, reconnect devices one at a time to find the source.

No message appears when you press the pedal

The pedal may be connected to the wrong jack, the keyboard may not be sending its input over MIDI, or the browser may not have MIDI access. Check the connection and device selection, then test the pedal using the keyboard's own sound or a compatible music app. The browser test only shows messages that the connected device sends to the browser.

How to fix unexpected values

1. Reconnect the pedal firmly. Unplug it, check for dust or visible damage, and insert the plug fully into the jack labeled for sustain. If the keyboard has separate sustain and expression jacks, make sure you are using the intended one.
2. Check the pedal type or mode. In the keyboard's settings or control software, choose a switch-style pedal if you want simple on and off sustain. Choose continuous or half-damper mode only if both the pedal and keyboard support it.
3. Check polarity before restarting. Some pedals have a polarity switch, and some keyboards detect pedal polarity when they power on. Set the switch as the pedal maker recommends, then restart the keyboard with the pedal released. If pressing and releasing still behave backward, see why a sustain pedal acts backward when plugged in.
4. Calibrate a continuous pedal. If the keyboard offers a pedal calibration option, follow its instructions from fully released to fully pressed. A poor calibration can make the usable range uneven or leave the pedal partly active at rest.
5. Set the pedal assignment. Assign the pedal to CC64 for sustain. If it is assigned to another controller number, the messages can be valid but control the wrong function.
6. Check browser permission and retry. Allow MIDI access for the test site in your browser's site permissions, then reload the page and select the device again. If the MIDI Test does not work in Safari, use a different browser.

Windows 11 and macOS do not have a universal system menu for choosing a sustain pedal's MIDI mode. Those controls are usually in the keyboard itself or its maker's software, so follow the menu names shown by your device rather than changing unrelated sound settings.

When the pedal or keyboard may be faulty

Try the pedal on another compatible keyboard, or try a known-working pedal on yours. If the same pedal sends unstable values on multiple devices, inspect its cable and plug. If another pedal behaves normally on your keyboard, the original pedal is the likely fault. If both pedals misbehave on one keyboard, the keyboard's jack or input circuit may need service.

Do not force a plug into a jack or repeatedly wiggle it while the keyboard is powered on. If the cable is damaged or the pedal continues sending erratic values after checking its mode and calibration, replacement is usually more practical than repair.

Why continuous values do not always mean a problem

MIDI controller values commonly use a scale from 0 to 127. A switch pedal can use the low and high ends of that scale, while a continuous pedal can send intermediate values too. A sustain pedal that reports a sequence such as 0, 20, 45, 80, and 127 while moving may be working as designed, especially if the keyboard supports half-pedaling.

What matters is whether the values match the pedal's intended mode and the response you want from your instrument. The MIDI Test can show what the device sends, but it cannot tell you whether a particular synthesizer or music app interprets those messages the way you expect.