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PHCC Daughterboards


PHCC Daughterboards Overview

explain Daughterboards here.


  • Digital
    • Switches
    • momentary contact
      • Pushbuttons
    • permanent contact
      • Flip Switches
      • Rotary Switches
        • just as rotary selectors, eg. Power Sel: APU, external Power, Engines
        • as incremental switches, eg. turning left decrements, turning right increments
    • ... and similar momentary or permanent on/off devices
    • Rotary Encoders
      • 2 bit gray code quadrature
      • mechanical
      • optical
  • Analog
    • potentiometers
    • other devices with 0-5V variable output

Digital Inputs

Each PHCC Motherboard can read up to 1024 digital input channels. These inputs are available through Keymatrix Daughterboards. Each Keymatrix Daughterboard provides 64 inputs, in an 8x8 matrix. Each PHCC Motherboard allows up to 16 Keymatrix Daughterboards to be connected.

The matrix organization means that you only need 16 (instead of 128) wires from PHCC to each set of 64 switches.

Keymatrix Daughterboards

  • KEY64D_PH
  • KEY64D_SC35
  • KEY64_251 (Strictly speaking NOT in matrix organization. Has one common wire for each input. So, there are 64+1 wires per board.)

Quadrature Rotary Decoder

Decodes quadrature encoded signals from mechanical and optical rotary encoders and makes the signals available for input to the Keymatrix Daughterboards.

Analog Inputs

Analog input (0-5V) or variable-resistance devices (aka. potentiometers, rheostats) can be used as an input to the PHCC system via the 35 analog inputs on the


General Information

Available or planned outputs

You want to control

  • LEDs
  • 7segment displays
  • alpha-numeric segmented displays
  • bar graph segmented displays
  • character lcd displays
  • lamps
  • relays
  • solenoids
  • d'arsonval movements (meter movements, those small coiled instruments found eg in analog multimeters)
  • air core instruments
  • steppers
  • servos
  • dc motors
  • Planned for the future: Syncro driver.

Analog Output Daughterboards

Digital Output Daugterboards

Servo Controller Daughterboards

Stepper Controller Daughterboards

Aircore Controller Daughterboards

LED, 7-segment displays, and other segmented displays

Segmented displays (7-segment, 14-segment, starburst, etc), LED bargraphs, as well as individual LEDs can be driven by the following controllers:


see UPHCC sister project.

There has been a DOA bus based LCD controller prototype (DOA_char_lcd), but it was determined that the DOA bus does not have the bandwidth to properly drive LCDs with frequent updates, esp. not when several displays are connected and need to share bandwidth among themselves and all other types of DOA daughterboards.

The UPHCC-lcd board (see link above) is much more versatile, as it supports 4-12 displays, allows LCDs with different controller types (read communications protocols), and supports both character dot matrix as well as graphical dot matrix displays. UPHCC-lcd even allows you to mix and match displays of the just described variations.

D'Arsonval Meter Movement

D'Arsonval meter movements, aka. galvanometers, can be controlled directly from the DOA_AnOut1 outputs.


USB interface

The default method to connect PHCC to the computer is via the RS-232 serial port. While PHCC could do more, most PCs are limited to 115200 bit/second. This puts the effective bandwidth at about 11520 bytes/sec.

The problem is that new computers often don't have serial ports anymore. They want you to use the Universal Serial Port (USB) instead.

So, PHCC gives you the option to plug in a small daughterboard (PHCC_iface_USB_FTDI232) directly onto the motherboard Instead of using the RS-232 serial port. You have to remove the MAX232 IC though.

This board is described here:

Note: Instead of the PHCC_iface_USB_FTDI232 board, you can just buy a standard USB-serial adapter. This is easier, cheaper, and does exactly the same thing.

Bus Terminator

  • DOB_term (terminator for the end of the DOB bus)

Bus Repeater/Amplifier

see Bus Differential Converter.

Bus Differential Converter



  • THVP, a parallel port PIC microcontroller programmer (aka. PIC burner)