Voice Over IP – Software Western Washington University By: Jonathan R. Peterson

Kernel Selection MicroC/OS-II  Manages complicated timing  Preemptive multitasking  Message passing with Semaphores (pending)

Task and ISR Overview EPHY_ISR  Sets a Semaphore every time a physical change occurs on the network. (Network cable plugged/unplugged) TimerISR  Handles the interrupt generated every 8kHz. StartTask  Completes system initialization and task creation, removes itself from the task scheduler. EthernetTask  Responds to the Semaphore created by EPHY_ISR and updates the link status. TCPIPTask  Scans the Rx buffers for new data and then processes it.

Task and ISR Overview (continued) DHCPTask  Handles dynamic addressing, and renews the IP address when the lease expires. KeyTask  Scans the keypad for a keypress. OnHookTask  Scans the button on bit 2 of Port-G to see if the receiver is in use or not. VOIPTask  Processes audio packets (incoming and outgoing), handles VOIP call requests and acknowledgements (handshaking). UITask  Displays user information via the LCD, and receives user input via the keypad.

Task and ISR Specifications Task/ISRPriorityOperationPeriod Execution Time Average CPU Load Maximum CPU Load EPHY_ISR---Sporadic5s1µs TimerISR---Periodic 8kHz125µs~40µs0.32 StartTask ms--- EthernetTask5Periodic 1ms (pends on EPHY_ISR) Typical: 57.2µs Max: 115.2µs TCPIPTask6Periodic2ms Typical: 353µs Max: 724µs DHCPTask7Periodic2ms Typical: 1µs Max: 100µs KeyTask8Periodic15ms Typical: 1µs Max: 2.2µs OnHookTask9Periodic15ms Typical: 1µs Max: 2.2µs VOIPTask10Periodic2ms~150µs0.075 UITask11Periodic200ms~5ms0.025 Total:

ISR Details – EPHY_ISR Description: This ISR is generated when a physical change occurs on the network.  Link speed  Duplex  Cable plugged/unplugged The ISR posts to a semaphore so that that EthernetTask may process the change. Details: Period: ~5s (Sporadic) Execution Time: ~1µs

ISR Details – TimerISR Description: This ISR handles the precise timing required for audio capture & reproduction. Details: Period: 125µs (8kHz) Execution Time: ~40µs

Task Details - StartTask Description: Performs all system initialization Creates the tasks Removes itself from the task scheduler Details: Priority: 4 Period: Once upon system startup Execution Time: 24.7ms

Task Details – EthernetTask Description: Pends on the Semaphore posted by EPHY_ISR. Determines what variety of link change occurred and updates the system. Details: Priority: 5 Period: 1ms Execution Time: 57.2µs

Task Details - TCPIPTask Description: Checks the Rx buffer for received packets. Writes to the Tx buffer when necessary. Processes packets through all layers except the application layer (described on the next slide). Details: Priority: 6 Period: 2ms Execution Time: 353µs

TCP/IP Details

Task Details - DHCPTask Description: This task processes the DHCP requests, and renews the lease of the IP address before it expires. Details: Priority: 7 Period: 2ms Execution Time: 1µs

Task Details - KeyTask Description: This task scans the 4x4 keypad, waiting for a key to be pressed. This is the same task that we used in ETEC 454. Details: Priority: 8 Period: 15ms Execution Time: 1µs

Task Details - OnHookTask Description: This task scans the push-button on bit 2 of Port-G and waits for a voltage level change. Details: Priority: 9 Period: 15ms Execution Time: 1µs

OnHookTask – De-bouncing

Task Details – VOIPTask Description: This task processes the incoming and outgoing audio packets, as well as handles VOIP call requests and acknowledgements. Details: Priority: 10 Period: 2ms Execution Time: ~150µs

VOIPTask – Incoming Call

VOIPTask – Outgoing Call

Task Details – UITask Description: This task is responsible for displaying information to the user via the LCD. The task also processes the user input. Details: Priority: 11 Period: 200ms Execution Time: ~5ms

Module Descriptions ATD – Analog to Digital conversions DHCP – Dynamic IP support EEPROM – Interface for the SPI to access the EEPROM Ethernet Driver – Allows Ethernet functionality IP – Internet Protocol support Keypad – Interfaces with the 4x4 keypad (**REUSED**) LCD – Displays text via the 2x16 LCD (**REUSED**) SPI – Handles synchronous serial communications TCP/IP – Integrates the Ethernet driver, IP, UDP and DHCP Timer – Configures the 8kHz sample rate UDP – User Datagram Protocol, Part of the TCP/IP stack VOIP – Contains the User Interface and application specific code.

Module Details ATDDHCPEEPROM Ethernet Driver IPKeypadLCDSPITCP/IPTimerUDPVOIP ISRs --- EPHY_ISR--- TimerISR--- Tasks ---DHCPTask---EthernetTask---KeyTask--- TCPIPTask--- StartTask --- OnHookTask --- VOIPTask --- UITask Public Func. ATDInitIsDHCPInitEEInitEthernetIsIPXXInitSPIUDP_WriteDataInitTimerIsUDPmain StartATDDHCPReqWriteEECloseEthernetMakeIPHdrXXWriteSPIGetAppDataGetCountMakeUDPHdr--- ReadEEStartTxIsICMPXXReadSPI--- CheckRxBuffersMakeICMPXX--- MakeEthHdrIsARPXX--- IsEthernetMakeARPXX--- Public Vars ---DHCPState---ActiveBufferMyNodeXX---VOIPFlag--- TxData[ ] ---DHCPAddr---GotLinkNodeBuf[ ]XX--- RxData[ ] --- CurrNodeXX---

General System Dataflow TimerISR SPI Ethernet EPHY Ethernet Driver IP/ICMP UDP RxData[ ] TCP/IP VOIP Rx Ethernet EPHY Ethernet Driver IP/ICMP UDP TxData[ ] TCP/IP VOIP Tx ATD DHCP DACFilter MI C

Basic Dataflow OSSemPend( ) EPHY_ISR Ethernet Driver EthernetTask LinkFlag GotLink TCP/IP IsEthernet( ) TCPIPTask IP IsIP( ) IsUDP( ) UDP IsDHCP( ) DHCP VOIP VOIPTask VOIPFlag

Keypad Dataflow VOIP KeyInit( ) KeyPend( ) Key KeyFlag Keypad Driver KeyTask KeyCodeTable Keypad I/O