Capacitive Shunt Sensing Game Controller System Software Design - - PowerPoint PPT Presentation

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Feb 13, 2023 108 likes •294 views

Capacitive Shunt Sensing Game Controller System Software Design By: Marcin Lobrow Western Washington University 2010 General System Design MCU: CY8C3866AXI-040ES2 Bus frequency 24 MHz 64Kb Flash, 2Kb RAM System Memory

SLIDE 1

Capacitive Shunt Sensing Game Controller

System Software Design By: Marcin Lobrow Western Washington University 2010

SLIDE 2

General System Design

 MCU: CY8C3866AXI-040ES2

Bus frequency 24 MHz
64Kb Flash, 2Kb RAM

 System Memory Requirements

500 bytes Flash
4Kb RAM

 Resources Used

25 GPIO, USB D+, D- Pins

SLIDE 3

Kernel Selection

Simple Time Slice Kernal
10 ms Slice Period
Easy Design
Round Robin Scheduling
Equal Priority Among Task
3 Tasks
2 ISR

SLIDE 4

Tasks & ISR



Tasks

1) Scan Capacitive Sensors Task 2) Angular Pitch Calculation Task 3) UI Button Task



Interrupt Service Routine (ISR)

1) Start DMA transfer of Memory to USB 2) Pause DMA transfer of Memory to USB

SLIDE 5

State Diagram

STATE 3 UI BUTTON TASK IDLE STATE 1 SCAN CAPACITIVE SENSORS STATE 2 PERFORM ANGULAR CALCULATION

TASK1 TASK1 COMPLETE TASK2 TASK2 COMPLETE TASK3 TASK3 COMPLETE

SLIDE 6

Initialization

System Initialization
Initialize Capacitive Sensors
Initialize Dynamic Memory Allocation
Initialize USB
Set Initial State
Period
One Execution
Execution Time
Approx 10 ms

SLIDE 7

Scan Capacitive Sensors Task

Description:

Scans the 4 Capacitive Sensors
Places Raw Data into Memory
Period: 10ms (Periodic)
Execution Time: 1 ms (max)

SLIDE 8

Angular Pitch Calculation Task

Description:

Calculates Angle of Users Hand
Calculates Constant Baseline For Signal
Calculates Change above Baseline Signal
Stores Delta in Memory
If Delta, Set DMA ISR
Drives LED Array
Period: 10 ms (Periodic)
Execution Time: 5ms (max)

SLIDE 9

UI Button Task

Description:

Scans ports for User Button Presses
Starts USB Communications with Start Button
Ends USB Communications with End Button
Sets ISR with Pause Button
Period: 100 ms (Periodic)
Execution Time: 1us (max)

SLIDE 10

Interrupt Service Routines

Description:

DMA_START_ISR
Starts DMA Data Transfer to USB
Triggered by Movement of Hand Above Sensors
DMA_STOP_ISR
Stops (Pauses) DMA Data Transfer to USB
Triggered Pause UI Button
Period: 20ms (min) (Sporadic)
Execution time: 100 us (max)

SLIDE 11

CPU load

L max = (1ms) + (5ms) + (1us) + (200us) (10ms) (10ms) (100ms) (20ms) L max = 60.1% L average = < 50.0 %

SLIDE 12

Modules

Module Tasks & ISR Public Functions and Data main.c InitializeGC() WaitForSlice() UITask() CapSense_Start() CapSense_Stop() ScanPort() DriveLEDs() SensorController.c ScanCapSensors() DMA_Start_ISR() DMA_Stop_ISR() CapSense_CSD_ScanSlot() CapSense_CSD_ReadSlot() SensorCalculation.c CalculateCapSensors() CalculateBaseline() CalculateDelta()

SLIDE 13

Overall Data Flow

TimeSlicer

Initialization

ScanCapSensor Module

USB Modules

CalculateCapSensor Module

UI Button Task main.c Check Port Update LEDs DMA_START_ISR DMA_STOP_ISR DMA

SLIDE 14

ScanCapSensor Data Flow

main.c

SensorTop TimeSlice(Task1) Ts =1ms

SensorController.c

ScanCapSensors() SensorRight SensorBottom SensorLeft StoreRawData()

SLIDE 15

CalculateCapSensor Data Flow

main.c

SensorTopRaw TimeSlice(Task2) Ts =5ms

SensorCalculation.c

CalculateCapSensors() SensorRightRaw SensorBottomRaw SensorLeftRaw UpdateBaseline() UpdateDetla()

SLIDE 16

Dynamic Memory Allocation Data Flow Diagram

USB DMA_START_ISR DMA_STOP_ISR DMA SensorRightDelta SensorLeftDelta SensorTopDelta SensorBottomDelta

SLIDE 17

Questions?

System Software Design By: Marcin Lobrow Western Washington University 2010