MSD Detailed Design Review AgendaP11212 : LVE Controls, RF Module

• Meeting Purpose• 1. Present an overview of the project.• 2. Review Detailed Design.• 3. Establish understanding of the Design through Feasibility analysis.• 4. Review Test Plan and Plan to meet Customer Needs.• 5. Discuss feasibility and possible alteration of plan.• Materials to be Reviewed• 1. Project Description • 2. Engineering Specifications• 3. Preliminary Test Plan / Plan to meet customer needs• 4. Risk Assessment and Actions to minimize Risk• 5. Bill of materials• 6. Drawings and Schematics• 7. Feasibility Analysis• 8. Thoughts and Concerns

Meeting TimelineStart Time Topic of Review

1:00 Project Introduction1:10 Engineering Specifications1:20 Test Plan1:40 Risk Assessment1:50 Bill of Materials2:00 Drawings and Schematics2:20 Feasibility Analysis2:50 Are we ready to move forward?

Engineering Specifications

Preliminary Test Plan

Risk Assessment

Risk Assessment

Bill of Materials

GUI Code Structure

GUI Mockups

• GUI mockups are images meant to get the idea of the GUI, rather than a working implementation

• The following windows have been mocked up:– The Main window– The Main window’s menu bar– The joystick configuration screen– The keyboard configuration screen

Main GUI

Main GUI Connect Menu

Main GUI Options Menu

Joystick Control Options

Keyboard Control Options

Arduino Code Structure

Schematic

PCB Layout

L298 Block Diagram

L298 Pinout

DC Motor Control

L298 High Current configuration

Nano Devboard Schematic

System Analysis

• Delay through transmission: – Theoretical message size: 18 bits – Single Message Latency:

• Time through USART: 18b / 31kBps = 72us • Time through RF: 18b / 40kbps = 450us • Total time: 72us + 450us = 522us

– Max messages: 5 – Max messages size: 90 bits – Max Message Latency:

• Time through USART: 90b / 31kBps = 362us • Time through RF: 90b / 40kbps = 2.2ms • Total time: 362us + 2200us = 2.562ms

– Forward Backward Left Right M1 + M1 - M2 + M2 - M3 + M3 - M4 + M4 - M5 + M5 - M6 + M6 - M7 + M7 - M8 + M8 – – 5 bit: instruction 0-31 – 4 bit: speed 0-15 – X bit: redundancy – 5 instructions at once – (5+4+9)*5= 90 bits/instruction set

System Analysis

• VIN = 7.2v

• IOUT(max)= 3.3A per motor• Absolute Max ratings• VSS=50v

• IO

• Peak non-repetitive = 3A• Repetitive = 2.5A• DC operation = 2A• PTotal= Total power Dissipation at 75C is 25W• Operating temperature -25C to 130C• As you can see the Peak non-repetitive is below the possible IOUT so an alternative configuration is

required. From the L298 data sheet found at http://www.st.com/stonline/books/pdf/docs/1773.pdf• Using a Paralleled input and output configuration the L298 can support up to 3.5A of repetitive peak

current.• Design will require 1 L298 in a paralleled configuration per motor.• PTotal >= VIN*IMAX 25 > 23.76

• VIN<= VSS MAX

System Analysis

System Analysis

• VLOGIC from Nano dev board is 5V which falls within the acceptable range.

• IIH from Nano dev board is 40μA which is less than 100μA• Requirements for Ardunio Nano• Input Voltage 6-20V, 7.2 falls in the range• Current draw on the Nano Dev board• L298 72mA• Atmega 12mA• L298ENABLE 2mA• FTDI 15mA• LEDs 5mA• Total draw = 116mA• Total supported 500mA

System Analysis

• Based on previous years thermal considerations the primary concern for heat generation in the design was the voltage regulation. Because our current design does not have a voltage regulator besides the one on the Micro-Controller dev board it will not have to be considered. The next board component of concern was the H-bridge for this the following equations will be used

• Δt = PDMAX * Rjc and Tjmax = Δt + Tamb

• PDMAX=25W

• Rjc= 3C/W• Δt=75C• Tjmax = 75+22=97C• This value is within the effective operating range of -25 to 130C.