gnrc_networking_mac example

This example shows you how to try out communications between RIOT instances with LWMAC as the MAC layer ptotocol for IEEE 802.15.4 devices. This example is generally based on gnrc_networking but embeds LWMAC to support low duty-cycle operation to conserve power. Also, it intends to show that the duty-cycled LWMAC can support popular upper layer protocols like UDP and RPL. Currently, it seems that you can only use the samr21-xpro board to test this MAC, since some certain features of the protocol are only available on that platform. Also, the current implementation of LWMAC uses RTT as the underlying timer source. So, currently, LWMAC cannot run on nodes that don't have RTT. But, as a long-term plan, we will replace RTT by a general timer API as the underlying timer to make LWMAC available for more devices, when the related implementations are ready.

Usage

Build, flash and start the application:

export BOARD=your_board
make
make flash
make term

Print out the achieved duty-cyle of LWMAC

You can print out the radio duty-cyle (a roughly one) of LWMAC by setting the LWMAC_ENABLE_DUTYCYLE_RECORD flag in sys/include/net/gnrc/lwmac/types.h to "1". By doing so, each time when a device sends or receives a packet, it will print out its radio duty-cycle value. Also, by further enabling the debug flag in sys/net/gnrc/link_layer/lwmac/tx_state_machine.c, you will get the printout of how many preamble (WR) and time (sending delay) cost for sending this packet in the TX procedure of LWMAC.

Try UDP transmissions with LWMAC

In the RIOT shell, get to know the IP address of one node:

2017-06-06 15:05:48,279 - INFO # ifconfig 2017-06-06 15:05:48,284 - INFO # Iface 7 HWaddr: 79:f6 Channel: 26 Page: 0 NID: 0x23 2017-06-06 15:05:48,288 - INFO # Long HWaddr: 79:67:35:7e:54:3a:79:f6 2017-06-06 15:05:48,297 - INFO # TX-Power: 0dBm State: SLEEP max. Retrans.: 3 CSMA Retries: 4 2017-06-06 15:05:48,303 - INFO # CSMA MTU:1280 HL:64 6LO RTR IPHC 2017-06-06 15:05:48,306 - INFO # Source address length: 8 2017-06-06 15:05:48,309 - INFO # Link type: wireless 2017-06-06 15:05:48,314 - INFO # inet6 addr: ff02::1/128 scope: local [multicast] 2017-06-06 15:05:48,320 - INFO # inet6 addr: fe80::7b67:357e:543a:79f6/64 scope: local 2017-06-06 15:05:48,326 - INFO # inet6 addr: ff02::1:ff3a:79f6/128 scope: local [multicast] 2017-06-06 15:05:48,331 - INFO # inet6 addr: ff02::1a/128 scope: local [multicast]

and start a UDP server.

> udp server start 8808

This node is now ready to receive data on port 8808.

In a second terminal, start a second RIOT instance, in the RIOT shell, you can now send a message to the first RIOT instance:

> udp send fe80::7b67:357e:543a:79f6 8808 testmessage

In your first terminal (the receiver side), you should now see output that looks like this:

2017-06-06 15:00:06,894 - INFO # [LWMAC]: achieved duty-cycle: 10 % 2017-06-06 15:00:06,896 - INFO # PKTDUMP: data received: 2017-06-06 15:00:06,901 - INFO # ~~ SNIP 0 - size: 11 byte, type: NETTYPE_UNDEF (0) 2017-06-06 15:00:06,907 - INFO # 00000000 74 65 73 74 6D 65 73 73 61 67 65 2017-06-06 15:00:06,911 - INFO # ~~ SNIP 1 - size: 8 byte, type: NETTYPE_UDP (5) 2017-06-06 15:00:06,914 - INFO # src-port: 8808 dst-port: 8808 2017-06-06 15:00:06,917 - INFO # length: 19 cksum: 0xf729 2017-06-06 15:00:06,921 - INFO # ~~ SNIP 2 - size: 40 byte, type: NETTYPE_IPV6 (3) 2017-06-06 15:00:06,925 - INFO # traffic class: 0x00 (ECN: 0x0, DSCP: 0x00) 2017-06-06 15:00:06,927 - INFO # flow label: 0x00000 2017-06-06 15:00:06,930 - INFO # length: 19 next header: 17 hop limit: 64 2017-06-06 15:00:06,934 - INFO # source address: fe80::7b67:877:19f:331e 2017-06-06 15:00:06,938 - INFO # destination address: fe80::7b67:357e:543a:79f6 2017-06-06 15:00:06,943 - INFO # ~~ SNIP 3 - size: 24 byte, type: NETTYPE_NETIF (-1) 2017-06-06 15:00:06,945 - INFO # if_pid: 7 rssi: 51 lqi: 255 2017-06-06 15:00:06,946 - INFO # flags: 0x0 2017-06-06 15:00:06,949 - INFO # src_l2addr: 79:67:08:77:01:9f:33:1e 2017-06-06 15:00:06,952 - INFO # dst_l2addr: 79:67:35:7e:54:3a:79:f6 2017-06-06 15:00:06,956 - INFO # ~~ PKT - 4 snips, total size: 83 byte

In your second terminal (the sender side), you should now see output that looks like this:

2017-06-06 15:00:06,871 - INFO # udp send fe80::7b67:357e:543a:79f6 8808 testmessage 2017-06-06 15:00:06,877 - INFO # Success: sent 11 byte(s) to [fe80::7b67:357e:543a:79f6]:8808 2017-06-06 15:00:06,890 - INFO # [LWMAC-tx]: spent 1 WR in TX 2017-06-06 15:00:06,894 - INFO # [LWMAC-tx]: pkt sending delay in TX: 8422 us 2017-06-06 15:00:06,898 - INFO # [LWMAC]: achieved duty-cycle: 10 %