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:

Open Identified Tasks

Task Description	Blocking Factors/Action Items/Progress	Status
Bench Power Supply	Blocked by Lack of suitable case Action: Visit Robinson's Hardware, check out aluminum sheet Blocked by: Lack of a Bending Brake Action: Make a Bending Brake Action: Bend Some Tin Action: Test what load Resistor will turn on the power supply Action: Drill Mounting Holes for Load Resistor Mount the power supply in the hand built case Blocked by: No way to extract power from power supply without cutting wires Action Taken Ordered 24 Pin Socket from E-Bay	Proceeding in part
Flightgear Rasberry Pi Client	Ready To Start Create Data Structures Flightgear Aircraft Property Table Cockpit Hardware Table Flightgear Connection Table Build Test Stubs with data for these tables Investigate Exporting/Importing the data from XML files Find out if a node server could drive or call the client	Status
Task Description	Blocking Factors/Progress	Status
Task Description	Blocking Factors/Progress	Status

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