Team 1907: Networked CAN Bus Controller Sponsor: Collins Aerospace - - PowerPoint PPT Presentation

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Jan 22, 2023 16 likes •186 views

Team 1907: Networked CAN Bus Controller Sponsor: Collins Aerospace (formerly UTC Aerospace) Team: Matthew Cox, Pawel Bezubik, John Nguyen Advisor: Dr. John Chandy Outline Project Overview Deliverables: Circuit Design and Analysis

SLIDE 1

Team 1907: Networked CAN Bus Controller

Sponsor: Collins Aerospace (formerly UTC Aerospace) Team: Matthew Cox, Pawel Bezubik, John Nguyen Advisor: Dr. John Chandy

SLIDE 2

Outline

Project Overview
Deliverables:

○ Circuit Design and Analysis ○ PCB Layout ○ Software

Schedule Review
Budget Review
Closing Remarks / Questions

SLIDE 3

Project Overview

Design a Controller Area

Network (CAN) Bus controller for an aerospace PCI rack.

Allows for distributed control and

sensing of multiple devices.

Create an interactive sensor

network using multiple nodes.

Deliverables:

I/O Circuit Designs
Printed Circuit Board
Preliminary board software

SLIDE 4

Circuit Design - Overview

Three initial I/O modules on board:

○ Discrete Input: Scale and convert power supply voltage to logic level signal ○ Analog Input: Scale 0-10V sensor input to 0-5V input for on board Analog to Digital Converter (ADC) ○ Current Source: Provide a controllable 0-200mA current source

Power Supply: Provide 12V and 5V rails from 16-32V unregulated

input

Microcontroller: Interface with CAN Network and control modules

SLIDE 5

Circuit Design - Discrete Input

Uses voltage divider and comparator

to provide simple logic level outputs to MCU

Low pass filter for switching

transients

Works with full range of supply

voltages

LM393 is low power, single supply,

supports common mode input range and comes in a dual package to save space

Vsupply Comparator V+ 16V 1.88V 28V 3.29V 32V 3.76V

Figure 1: Discrete Input Stage Figure 2: Reference Voltage

SLIDE 6

Circuit Design - Analog Input

Circuit filters signal and buffers using unity-gain op amp
Signal is then divided and buffered again before reaching ADC
Allows 0-10V sensors to be read by 0-5V ADC on Microcontroller

Figure 3: Analog Input Stage

SLIDE 7

Circuit Design - Power Supply

Off the shelf part to save time and space
Board input is 16-32V unregulated
Chosen Part: LT8616 Buck Converter

○ Input range up to 42V ○ Configurable switching frequency ○ Dual outputs capable of 1.5A & 2.5A

12V output rail to bias amplifiers
5V output rail for digital components
Design goal: minimum 45° Phase Margin

at fsw at room temp

Figure 4: Main Power Supply

SLIDE 8

Circuit Design - Current Source

Design Criteria:

0 - 200mA adjustable

range

Controllable by MCU

Process:

Design and testing in

LTSPICE

Control system design in

MATLAB/Simulink

Board level verification

Figure 5: Final Current Source Block Diagram Figure 6: Early LTSpice Concept Figure 7: Full Circuit Model in LTSpice

SLIDE 9

Circuit Design - Microcontroller

Chosen MCU: ATSAMC21J18A
Chosen for:

○ 5V Tolerant MCU ○ Integrated CAN Bus Controller ○ On board ADC ○ Lots of documentation

Programmable via JTAG port &

Atmel Studio

Figure 8: MCU Board Layout

SLIDE 10

PCB Design - Overview

4 Layer PCB Stack-up:

1. Signal 2. PWR 3. GND 4. Signal Design Considerations:

Split power plane design
Low impedance paths for

switching power supply

Dedicated ground plane
Differential pair routing

Figure 9: PCB Floor Plan

SLIDE 11

PCB Design - Assembly & Test

Assembly:

Utilized hot air soldering
Verified part values and orientation before

placement

Inspected and fixed any solder bridging

Test:

Extensive continuity check of traces
Verified node voltages from design
Tested module functionality using external

supply

Figure 10: Final Assembled Board

SLIDE 12

Software Design - Overview

Main Software Components:

CAN RX Handler
CAN TX Handler
Current Source Control
Discrete Input Module
Analog Input Module

Figure 11: CAN RX Flow Diagram Figure 12: CAN TX Flow Diagram

SLIDE 13

Software Design - CAN Message Format

Flexible address system
Multiple priority levels

CAN ID Bits Assigned Function [28:25] Priority Level [24:18] Destination Device ID [17:9] Origin Device ID [8:0] Command

Figure 13: CAN Data Frame Format

SLIDE 14

Software Design - Commands

Allow controllers to

interact with each other

Commands expose

hardware interface to

ther networked

devices

Up to 256 command

slots Name Description Command Byte

Heartbeat

Timed message that simply relays whether the controller is still connected and powered on

0x00 Status

Relay basic information about the module including serial number, software version, module information and status as well as configuration data.

0x01 Current Source - Enable/Disable

Relay basic information about the module including serial number, software version, module information and status as well as configuration data.

0x02 Current Source - Command Setpoint

Command a controller with a torque motor module to enable or disable the output

0x03 Analog Input - Status

Send a snapshot of current values of the analog input in configuration specified engineering units

0x09 Discrete Input - Enable Monitoring

Set the discrete input module of a controller to stop monitoring a switch for a level change event

0x06

SLIDE 15

Schedule Review

Major Milestones Scheduled Completion Date Actual Completion Date Difference Finalize Requirements 10/24/19 11/2/19 9 days Final Circuit Design Completed 2/15/19 2/19/19 4 days PCB Designed & Ordered 3/4/19 3/14/19 10 days PCB Assembled 3/15/19 3/29/19 14 days Software Demonstration Completed 4/26/19 In Progress - 70%

SLIDE 16

Budget

Vendor Cost (Includes S&H) Digikey - Dev Board $60.09 Digikey - JTAG Programmer $78.95 4PCB - Circuit Board Order $112.23 Mouser - PCB & Test Parts $41.36 Digikey - PCB & Test Parts $218.95 Total: $511.58

Development Expenditures: Board Unit Cost:

Item Cost PCB - Bill Of Materials $125.25 PCB (4-Layer, 106 cm2) $66 Total: 191.25

SLIDE 17