Lost Item PagerLost Item PagerSystem DesignSystem Design

Russ KinleyRuss Kinley5/6/60085/6/6008

MCU ChoiceMCU Choice

Base:Base: MC13213MC13213 16 MHz16 MHz Micro C/OS Micro C/OS 8KB ROM (flash)8KB ROM (flash) 2KB RAM2KB RAM

Pagers:Pagers: MC13211MC13211 16 MHz16 MHz Time-slice KernelTime-slice Kernel 2KB ROM (flash)2KB ROM (flash) 100 Bytes RAM100 Bytes RAM

Tasks (Base)Tasks (Base)

4.4. Start TaskStart Task5.5. Button Press TaskButton Press Task6.6. Send Receive TaskSend Receive Task7.7. Display TaskDisplay Task8.8. Count TaskCount Task

Start TaskStart Task Initializes systemInitializes system Creates other tasksCreates other tasks Priority: 4Priority: 4 Period: run-oncePeriod: run-once Execution Time: 1secExecution Time: 1sec

Button Press TaskButton Press Task Detects a valid button pressDetects a valid button press Priority: 5Priority: 5 Period: 10msPeriod: 10ms Execution time: 20usecExecution time: 20usec

Send Receive TaskSend Receive Task Sends start/stop page messagesSends start/stop page messages Reads return messages from PagersReads return messages from Pagers Priority:6Priority:6 Period: 1secPeriod: 1sec Execution time: 10msecExecution time: 10msec

Display TaskDisplay Task Determines which message is Determines which message is

displayed displayed Displays all messages on LCDDisplays all messages on LCD Priority: 7Priority: 7 Period: 1secPeriod: 1sec Execution time: 10msecExecution time: 10msec

Count TaskCount Task Used as a timer for Display Task’s Used as a timer for Display Task’s

displaydisplay Priority: 8Priority: 8 Period: 1secPeriod: 1sec Execution time: 10usecExecution time: 10usec

CPU Load (Base)CPU Load (Base)

Task Execution (ms) Period (ms) Load

Start 1 0 0

Button 0.02 10 0.002

Send/Receive 10 1000 0.01

Display 10 1000 0.01

Count 0.01 1000 0.00001

       

Max:     0.02201

Average:     0.012

Base ModulesBase Modules MainMain: Start Task, Display Task, : Start Task, Display Task,

Count TaskCount Task LCDLCD: (no tasks): (no tasks) ButtonButton: Button Press Task: Button Press Task WirelessWireless: Send Receive Task: Send Receive Task

Data Flow Diagram (Base)Data Flow Diagram (Base)

Pager TasksPager Tasks Start TaskStart Task Wake-up TaskWake-up Task Send Receive TaskSend Receive Task Button Press TaskButton Press Task Beep TaskBeep Task

Start TaskStart Task Initializes device upon resetInitializes device upon reset Period: run oncePeriod: run once Execution time: 1 secExecution time: 1 sec

Wake-Up TaskWake-Up Task Uses an RTI to awaken the pager Uses an RTI to awaken the pager

from sleep mode.from sleep mode. Period: 20msec(timeslice period)Period: 20msec(timeslice period) Execution time: 10usecExecution time: 10usec Holds pager awake for 1sec and in Holds pager awake for 1sec and in

sleep for 14sec to help not to miss a sleep for 14sec to help not to miss a signal and wait longer for a response signal and wait longer for a response and conserve battery.and conserve battery.

Button Press TaskButton Press Task Detects a valid button pressDetects a valid button press Signals others tasks to end functionSignals others tasks to end function Period: 20msec (when active)Period: 20msec (when active) Execution time: 10usecExecution time: 10usec

Beep TaskBeep Task Turns on/off LEDs and speaker with a Turns on/off LEDs and speaker with a

50% duty cycle overall.50% duty cycle overall. Period: 100usecPeriod: 100usec Execution time: 10usecExecution time: 10usec

Send Receive TaskSend Receive Task Receives signals from Base, Receives signals from Base,

determines if signal is intended from determines if signal is intended from that device. that device.

Returns acknowledge signals to BaseReturns acknowledge signals to Base Period: 500msec (25 time-slice Period: 500msec (25 time-slice

periods)periods) Execution time: 1msec (send), Execution time: 1msec (send),

15msec (receive)15msec (receive)

CPU LoadCPU Load

Task Execution (ms) Period (ms) Load

Start 1000 0 0

Button 0.01 10 0.001

Send Receive 0.1 10 0.01

Beep 0.01 0.1 0.1

Wakeup 0.1 15000 6.67E-06

       

Max:     0.111007

average:     0.011007

Data Flow DiagramData Flow Diagram