The Marshall Valvestate AVT 2000 – AVT Stage Foot Controller (it doesn’t seem to have a short codename as far as I can tell) is, as its name suggests, a foot controller for some of Marshall’s Valvestate series amps. It has 6 buttons (4 momentary, 2 toggle) and 6 LEDs. Connection to the amp is by way of a 15 pin D-sub connector.

DISCLAIMER: Use this information at your own risk. It may include mistakes or may differ from your own hardware. I assume no responsibility for damage to your equipment.

The four channel switches are momentary; along with their LEDs, they share a common ground (pin 14). There are no pull-up resistors for these switches, and the four LEDs have no resistors. The 2 DFX switches are toggle switches; they share the same common ground but their LEDs are wired differently. The anodes of the two DFX leds are wired via individual 220ohm resistors to pin 9. By applying an appropriate voltage (I would assume 5v) to this pin, the LEDs will light when the switches are not engaged; this means that if you have a pull-up on the switch then when you read a logic high the LED will be on.

The pinout for the 15 pin connector on the foot switch is as follows:

1 OD2 switch (momentary)
2 OD1 switch (momentary)
3 NC
4 OD2 LED Anode
5 OD1 LED Anode
6 Clean LED Anode
7 Ac Sim LED Anode
8 Clean switch (momentary)
9 Vled
10 Sim/Clean DFX Switch (toggle)
11 Ac Sim Switch (momentary)
12 NC
13 NC
14 Common Ground
15 OD1/2 DFX Switch (toggle)