Howto:C172P Cockpit Project

This Howto will develop into a detailed project plan for building a C172P Instrument Panel. While not a step by step guide, it will include details on the prototyping, design and building of a panel. The project includes the following major activities:

Description

The work product will match an actual C172P cockpit instrument panel as closely as possible given constraints of tool availability, time and money.

Versions:

1. A set of rotary encoders and switches in an overlay for a regular monitor
2. Expand the project to include items in the radio stack
3. Replace the monitor with individual instruments

Design Alternatives

• Instruments
  • Monitor Overlay
  • Individual Instruments
• Multi-value inputs
  • using potentiometers and ADC ports
  • Using magnetic encoders with:
    • AtMega driven pins
    • SPI
    • I2C
• Display of Numeric and Alphabetic data
  • driven by Maxim Max7221 on an SPI interface
  • driven directly by an AtMega processor
• Banks of switches and rotary encoders with a multiplexed parallel interface
• Raspberry Pi connected to one or more AtMega Processors via SPI or I2C
• Raspberry Pi connected to a 4 to 16 bit multiplexer to select SPI data
• Raspberry Pi responsible for interfacing raw data to flightgear property values
• Display of numeric and alphabetic data using 7 and 16 segment displays
  • drive with AtMega chip and Transistors
  • drive with Maxim Max7221CNG Integrated Circuit
• AtMega Processors with port expanders responsible for raw data
• AtMega Processors communicate with Raspberry Pi
  • Using SPI
  • Using I2C
• Telnet interface to Flightgear runs on Raspberry Pi
  • C programming language

== Code Development Activities

Client to Flightgear protocol

=== Client to AtMega protocol

Magnetic Encoders

• For Heading Adjusters on Instruments
• Replacement for Rotary Encoders
• Replacement for Potentiometers

Proof of Concept and Prototyping Activities

Client on PI

Communication with Flightgear using Telnet

• Change the value of a cockpit switch
• Read the value of a Com or Nav Radio's frequency
• Change a standby frequency
• Make a standby frequency the in use frequency
• Dim and brighten the instruments
• Move the throttle
• Move one of the control surfaces

SPI

• different speeds
• Error Detection and re-transmission
• Client to ATMega
• Client to Max7221
• Client to Port Expander

I2C

• different speeds
• Error Detection and re-transmission
• Client to ATMega
• Client to Port Expander

Client on AtMega

Communication

• I2c
• SPI
• Raw Data Protocol

Data Acquisition

• Switch
• Rotary Encoder
• Magnetic Encoder
• Potentiometer

Control Data

• Air Core
• Stepper Motor
• Lighting Level

Building

Hardware Choices

• AtMega Models
• Raspberry Pi III
• for 7 and 16 segment displays
  • Max7221
  • or 7 Segment Driver Transistors
• 4 to 16 Multiplexer
• Magnetic Encoder
• Rotary Encoder
• Slider Potentiometer:
• Power Supply: Bench Supply based on an ATX PC power supply
• Knobs
  • Heading Adjusters
  • Radio Stack Volume
  • Radio Stack Frequency Select
  • Radio Stack Buttons
  • Rotary Switches
  • Rocker Switches
  • Toggle Switches
  • Main Switches
  • Magneto Switch
  • Flaps Lever: Design the Mechanism to attach to a rotary switch