VFS5 Vox footswitch emulation and improved functions with Arduino Nano

Based on the reverse engineering from Whitelamp and the PWM implementation from @santoxyz

This is an emulator for the VFS5 Vox footswitch for their own amps running on a Arduino nano.

Features:

• 2 DPDT buttons support (up/down on channel selection)
• 4 Led for mode indication (solid light for the first four modes and blink for the second bank)
• Auto shutdown detection for saving the last channel activated on EEPROM
• Auto setting the last saved channel when connected
• Shelf powered from the amp connector (no need of batteries)

Schematic:

                               DPDT         DPDT

                               X X X+-----+X X X

                               X X X<+   +>X X X
                                     |   |
                               X X X |   | X X X
                                     |   |
                                 +---+   +-+
                                 |         |
              +------------------------------------------------------------------+
              |                  |         |                                     |
              |                  |         |                                     |
  FROM AMP    |             +----+---------+------+                              |
 +--------+   |             | bankPin  channelPin |                              |
 |        |   |             |                     |                              |
 |      T +-----------------+ VCC             OUT +---->1K2Ω+---+----->1k2Ω+-----+
 |        |   |             |                     |             |                |
 |      R | <-+    +--------+ GND   ARDUINO       |             |                |
 |        |        |        |        NANO         |             v                v
 |      S +--------+        |                     |           47nF             47nF
 |        |                 |                 GND +-----+       +                +
 +--------+                 |                     |     +-------+----------------+
                            | LED1 LED2 LED3 LED4 |     |
                            +--+----+----+----+---+     |
                               |    |    |    |         |
                               |    |    |    |         |
                               v    v    v    v         |
                              XXX  XXX  XXX  XXX        |
                              XXX  XXX  XXX  XXX        |
                              XXX  XXX  XXX  XXX        |
                               +    +    +    +         |
                               |    |    |    |         |
                               +----+----+----+---------+