1. Network Reprogramming Jaein Jeong, Sukun Kim Nest Meeting July 30, 2003

2. Concept Parallel programming –A mote is loaded program with direct connection Network programming –The program code is stored outside the program memory through radio packets. –Downloaded code is transferred to the program memory afterwards. PC Program Memory Mote Program Code Parallel programming. Base Station EEPROM Mote Program Code PC Program Memory Network programming

3. Components On motes –XnpM module handles most of the jobs. –Main application needs to be wired to XnpC. On PC –Xnp java program sends program code through radio. Message Formats –AMID: set to #47. –CMD: type of command (e.g., download, query and etc). –PID: Checksum for program code. Used for validation –CID: Sequence number for capsule PC Xnp javaAppXnpC Mote Radio packets 567:8 CMDSUBCMDPIDCIDData 9:1011:end0:1 DestAMID 2 GID 3 Len 4

4. Steps of network programming Download Phase Query Phase Reprogram Phase

5. Download Phase Start of download –Xnp java program sends a request and XnpM relays this request to the main module. –Main module can reserve resources and acknowledges to XnpM. –‘Download start’ message is sent multiple times. Xnp java program XnpM module Main module (1) Download start (2) Download request event (3) accept/deny by replying Download –java program sends each line of program as a capsule. –The capsule is stored in EEPROM by XnpM.

6. Query Phase A mote gets any missing capsules in query loop. 1.java program asks motes for missing capsules. 2.Each mote scans EEPROM and requests the retransmission of the next missing capsule. 3.In response, java program sends the missing capsule. 4.Other motes can also fill the hole as well as the requestor. Query loop ends when the java program doesn’t get request for several times. Xnp java program Mote 1 (1) Query for missing capsule Mote 3 Mote 2 (2) Request for retransmission (3) Retransmission of capsule (2) Scan (4) Fill the hole

7. Reprogram Phase The downloaded code is transferred to the program memory and the mote starts the new program. –First, java program sends a reprogram request. –After checking the EEPROM for correctness, XnpM transfers control to the boot loader. –The boot loader copies the code in EEPROM to program memory and reboots the system. After reboot, mote ID and group ID needs to set correctly.

8. Protocol PC Mote StartCompleteDownload StartCompleteReady for Download Download Phase Query 1234567343536833... 1234567343536833... 1234567343536833... Mote 1 Mote 2 Mote 3 PC Query Phase Service 2 Hole QueryService 3 Hole QueryService 1Query Timeout Completed !!! Hole

9. More detail in Phase 2 Query to all 1234567343536833... Mote 2 PC Query Phase Service 2 Hole Hole 2 Once Query to 2 Next Hole Hole 7 Once Query to 2Hole 7 Once Again EEPROM write failure Query to 2 Again Hole 7 Once Query to 2Hole 34 Once Query to 2 Timeout Next Hole Query to all Quit ‘Service 2’

10. Modification PC Mote StartCompleteDownload StartComplete Download Phase Query 1234567343536833... 1234567343536833... 1234567343536833... Mote 1 Mote 2 Mote 3 PC Query Phase Service 2QueryService 3QueryService 1Query Failure !!! Or Increase the number of control message retransmission

11. Modification (continued) PC Mote StartCompleteDownload StartCompleteReady for Download Download Phase Query 1234567343536833... 1234567343536833... 1234567343536833... Mote 1 Mote 2 Mote 3 PC Query Phase Service 1 Hole QueryService 3Query Timeout Failure !!! Completed Increase query timeout

12. Modification (continued) Query to all 1234567343536833... Mote 2 PC Query Phase Service 2 Hole Hole 2 Once Query to 2 Next Hole Hole 7 Once Query to 2Hole 7 Once Again EEPROM write failure Query to 2 Again Hole 7 Once Query to 2Hole 34 Once Query to 2 Timeout Next Hole Query to all Positive Ack Query to 2 Eliminate timeout using positive ack Quit ‘Service 2’

13. How to wire apps for network programming In configuration file (AppC), XnpC module should be connected to the implementation (AppM). In AppM, two events should be handled. XnpC AppM.Xnp AppC XnpM module AppM module Xnp.NPX_DOWNLOAD_REQ Xnp.NPX_DOWNLOAD_ACK XnpM module AppM module Xnp.NPX_DOWNLOAD_DONE Start download event Terminate download event

14. Location of Network programming module Check out these directories in CVS. –Tinyos-1.x/apps »XnpService: main module for network programming. »XnpCount: a sample app »XnpRfmToLeds: a sample app –Tinyos-1.x/tools/java/net/tinyos »Util_xbow: a modification to SerialStub »Xnp: xnp java program

15. Installing network programmable code A network programmable code should be loaded using parallel programming in the beginning. 1.Compile an application in ATmega128 native. –Currently, supported in mica2, mica2dot. –Latest tool: avr-gcc, nesC 1.1 and uisp needed. –Refer to http://webs.cs.berkeley.edu/tos/mica2.htmlhttp://webs.cs.berkeley.edu/tos/mica2.html 2.Load app binary in ATmega128 native mode. uisp -dprog=dapa --wr_fuse_e=ff -–erase uisp -dprog=dapa -–wr_fuse_e=ff -–upload if=main.srec uisp -dprog=dapa -–wr_fuse_e=ff -–verify if=main.srec 3.Load boot loader. uisp –dprog=dapa --upload if=bootloader.srec

16. Issues in PC side. Xnp java program –sends a command, a program capsule and hears the response from the motes. –sends/receives radio packets through UART. Different versions of GenericBase. –GenericBase »Easy to lose sync. Not recommended for network programming. –Sync GenericBase »Check sync bytes of UART packet. Works for both direct access and SerialForward –XGenericBase »Check sync bytes of UART packet. Only works for direct access Sync GenericBase with SerialForward is recommended.

17. Test Results Num Motes Num Tries Download Time (s) Query Time (s) Num Successes 4410624.254 8410672.257.75 1641066316 Test program: XnpCount –Program size: 37000 bytes, 841 capsules.

18. Test Results (Cont.) We could get reasonable success rate when motes are normal. Cases when network programming fails. –Parameters in xnp java is not correct. »When xnp sends packets faster than GenericBase can handle. »This can halt network programming globally. »Interval between each write should be large enough for GenericBase to handle. 120 ms was found by experiment. –Program code is not correctly loaded initially. »Mote doesn’t go into download mote. –A mote cannot write into its EEPROM. »This happened when battery voltage was low. And was fixed with new battery. –After hardware modification was made. »A mote didn’t work properly when we solder the loose battery connection. »We needed to load the code with parallel programming.

19. Discussion Can we assume that program image is correct just by checking PID and CID are correct? When mote #1 loses packet K, does its neighbor mote #2 also lose the packet? Experiments showed that query time increases with the number of motes. Will it be worthwhile to use Forward Error Correction (FEC) for larger number of motes? Does network programming justify the higher power consumption in favor of convenience? May need characteristic numbers about motes and TinyOS –Radio Speed, Packet loss rate –EEPROM Speed (read, write), write failure rate –Atomicity of EEPROM write