Using Interlink FSR400 for HiHat pedal

[jblain]

Hello,

I am trying to figure out if I can use an Interlink FSR as a pedal input on a hihat I am building. The one I am using is :

http://www.interlinkelectronics.com/FSR406.php

I measure the impedance on the fsr as :

Very high (mega ohms) when there is no pressure on the pedal
2 Kilo ohm when the smallest detectable pressure is applied
750 ohms when the pedal is fully pressed

Megadrum only gives me readings if Altin is set to yes. But it gives me readings that range from about 5 to 8. So I have no sensitivity...

How can I make it more sensitive ?
What am I doing wrong ?
Is this FSR usable

Regards

Jacques

[dmitri]

How did you connect the FSR? Did you use a pull up resistor to the pedal power?

[jblain]

How did you connect the FSR? Did you use a pull up resistor to the pedal power?

No I simply connected the two fsr pins directly to input 1 of the megadrum. When I press my mechanical peddle is presses against the FSR and changes its impedance.

I thought that input 1 (HiHat controller) of megadrum was for a variable resistor load (like a potentiometer).Do I need to supply external circuitry to generate voltage based on the FST resistance to input 1 of megadrum ?

If so were can i get the specifications for the require input voltage to pin 1 ?

[dmitri]

MegaDrum supplies some voltage on the HiHat input but it is only good enough for a simple switch type pedals. For a variable HiHat pedal you must also use HiHat power source to provide bias for good resolution. Basically, you connect your FSR to the ground and the HiHat pedal signal input and also add a biasing resistor between the HiHat pedal signal input and the HiHat power source. The value of this biasing resistor will depend on the variable resistor. In your case I think anything between 5k and 20k will be good.
On the modules I build the pinout on the HiHat pedal input is this: sleeve is ground, tip is signal and ring is power source.

[jblain]

MegaDrum supplies some voltage on the HiHat input but it is only good enough for a simple switch type pedals. For a variable HiHat pedal you must also use HiHat power source to provide bias for good resolution. Basically, you connect your FSR to the ground and the HiHat pedal signal input and also add a biasing resistor between the HiHat pedal signal input and the HiHat power source. The value of this biasing resistor will depend on the variable resistor. In your case I think anything between 5k and 20k will be good.
On the modules I build the pinout on the HiHat pedal input is this: sleeve is ground, tip is signal and ring is power source.

Thank you Dmitri, I will give it a try tomorrow

[jblain]

MegaDrum supplies some voltage on the HiHat input but it is only good enough for a simple switch type pedals. For a variable HiHat pedal you must also use HiHat power source to provide bias for good resolution. Basically, you connect your FSR to the ground and the HiHat pedal signal input and also add a biasing resistor between the HiHat pedal signal input and the HiHat power source. The value of this biasing resistor will depend on the variable resistor. In your case I think anything between 5k and 20k will be good.
On the modules I build the pinout on the HiHat pedal input is this: sleeve is ground, tip is signal and ring is power source.

Hello Dmitri,

Following your instructions, I was able to get my pedal to work correctly. I can now go from fully closed (127) to fully open (0) when I activate the pedal and monitor the midi log in the megadrum manager software.

However I am having difficulties configuring the hihat controller parameters. They do not correspond to the ones described here http://www.megadrum.info/content/hihat-pedal-settings . I am guessing my firmware is more recent than the documentation. Were can I find up to date information about the current set of hihat controller parameters ?

My problem is that right now, I only get midi 46 outputs (splash) from megadrum when I strike the hihat (single zone), regardless of the hihat pedal position ?

I can get chicks if I stomp the pedal.

[jblain]

MegaDrum supplies some voltage on the HiHat input but it is only good enough for a simple switch type pedals. For a variable HiHat pedal you must also use HiHat power source to provide bias for good resolution. Basically, you connect your FSR to the ground and the HiHat pedal signal input and also add a biasing resistor between the HiHat pedal signal input and the HiHat power source. The value of this biasing resistor will depend on the variable resistor. In your case I think anything between 5k and 20k will be good.
On the modules I build the pinout on the HiHat pedal input is this: sleeve is ground, tip is signal and ring is power source.

Hello Dmitri,

Following your instructions, I was able to get my pedal to work correctly. I can now go from fully closed (127) to fully open (0) when I activate the pedal and monitor the midi log in the megadrum manager software.

However I am having difficulties configuring the hihat controller parameters. They do not correspond to the ones described here http://www.megadrum.info/content/hihat-pedal-settings . I am guessing my firmware is more recent than the documentation. Were can I find up to date information about the current set of hihat controller parameters ?

My problem is that right now, I only get midi 46 outputs (mnote on channel 2 Hihat) from megadrum when I strike the hihat (single zone), regardless of the hihat pedal position ?

I can get chicks if I stomp the pedal.

[workroom]

The setup description here is still accurate http://www.megadrum.info/content/hihat-pedal-settings

The software has to be configured to match megadrum or megadrum has to be configured to match the software.

So, 1 what drum instrument are you using, and

2 what are your midi notes mapped to, in megadrum and the software. They need to corespond.

[jblain]

The setup description here is still accurate http://www.megadrum.info/content/hihat-pedal-settings

The software has to be configured to match megadrum or megadrum has to be configured to match the software.

So, 1 what drum instrument are you using, and

2 what are your midi notes mapped to, in megadrum and the software. They need to corespond.

Hello Dmitri,

I am using Superior Drummer, the latest version and I am using the default megadrum note mapping. Yesterday, I did some more investigating and I now understand that :

1) The pedal works ok, I can control the big VU meter very well but I can only get a midi output from 0 to 126 (not 127 whatever I do with the low and high settings).

2) FSR when activated changes impedance from about 5K to about 1K. But when I do not press on it and it is not activated, I get a very high impedance (about 10 mega ohm)

3) As long as I am pressing the pedal everything seems to work. I can vary the Hihat sound from closed to open, I can do chicks, I can do splash

4) If I release the pedal and FSR goes into high impedance mode, then when I hit the Hihat I only get splash note (46) not the fully opened note I was expecting and the one I get if I apply slight pressure on the pedal. That is the real problem I am having

Have a nice day

[workroom]

Hey man. I am not dmitri but trying to help. If you dont put your foot on the pedal it should play whatever note the hat bow is mapped to, i guess yours is mapped to the splash note. Change it in the pad settings.