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  • WIOpi-01
  • WIOpico
  • Headless Raspberry Pi Setup

The Raspberry Pi Pico can be used as WIOpi I2C slave for common tasks:

• 4 Servos or 32 NeoPixel
• 16 I/O (100ms scan)
• 2 four wire stepper (ULN2003)
• up to 4 Charlieplexing signals on both I/O banks

The NeoPixel protocol engine needs all interrupts on the Pico. This is the reason that it is not possible to combine servos and neopixel simultaneous on the same Pico.

The binary firmware can be downloaded here:
https://wiki.rocrail.net/rocrail-snapshot/WIOpico.ino.rpipico.uf2

1. Keep the Pico button pressed at connecting to USB.
2. The Pico will behave like a removable drive.
3. Copy the WIOpico.ino.rpipico.uf2 file on this drive.
4. Ready.

GND *--[2k2]--*--[2k2]--*--[2k2]--*--[2k2]--*--[2k2]--* VREF
    |         |         |         |         |         |
Jmp /         /         /         /         /         /
    0         1         2         3         4         0
    *---------*---------*---------*---------*---------* GP28

The GP28 value can be checked in the Monitor.

• Signal Aspect Values

A Rocrail signal with control aspects and port type multiplex, uses 4 pins starting with the port offset.
The refresh rate is about 250µs.
Aspect values are used from the details tab. 24bits are used, the upper 12bits are for blinking.
Example: LED 1 and 2 on and LED 2 blinking: 0x002003 → Aspect value = 8195

Diagram:

Signal setup for WIOpi 98 and slave 126:

Type ?<enter> in the monitor to check the configuration of the Pico:

WIOpico (c)Rocrail Oct 20 2021 10:47:03
I2C:126 (pixel=0 servo=20003F70 IO=FF 00 servo=00 GP28=4083 CNF=0 IO1=input IO2=output)

• https://www.raspberrypi.com/products/raspberry-pi-pico/