190 lines
6.2 KiB
Markdown
190 lines
6.2 KiB
Markdown
# Wireless / IEEE 802.15.4 / `i8sak` or `i8` IEEE 802.15.4 Swiss Army Knife
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## Description
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The i8sak app is a useful CLI for testing various IEEE 802.15.4 functionality.
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It also serves as a starting place for learning how to interface with the NuttX
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IEEE 802.15.4 MAC layer.
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The i8sak CLI can be used to manipulate multiple MAC layer networks at once.
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Both a MAC character driver interface and a network interface using sockets are
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supported. The MAC character driver is used in cases where networking is not
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enabled and you want your application to use IEEE 802.15.4 directly. In most
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cases however, you will probably be using 6LoWPAN networking support and
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therefore, the MAC can be controlled directly from the socket interface rather
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than the MAC character driver. IEEE 802.15.4 MAC character drivers show up in
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NuttX as `/dev/ieeeN` by default.
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When you invoke the first call to i8sak with a specified interface name, it
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creates an i8sak instance and launches a daemon to handle processing work. The
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instance is considered sticky, so it is possible to run `i8 /dev/ieee0` or `i8
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wpan0` at the beginning of a session and then can exclude the interface name
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from all future calls. The number of i8sak instances supported is controllable
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through menuconfig.
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The `i8sak` app has many settings that can be configured. Most options are
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_sticky_, meaning, if you set the endpoint short address once, any future
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operation using the endpoint short address can default to the previously used
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address. This is particularly useful to keep the command lengths down.
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## How To Use
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The i8sak app has a series of CLI functions that can be invoked. The default
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i8sak command is `i8` to make things quick and easy to type.
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In my test setup I have 2 Clicker2-STM32 boards from MikroElektronika, with the
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BEE-click (MRF24J40) radios. Choose one device to be the PAN Coordinator. We'll
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refer to that as device A.
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On that device, run:
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```shell
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i8 /dev/ieee0 startpan cd:ab
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```
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This will tell the MAC layer that it should now act as a PAN coordinator using
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PAN ID CD:AB. For now, this function assumes that we are operating a non-beacon
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enabled PAN, since, as of this writing, beacon-enabled networks are unfinished.
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Next, on the same device, run:
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```shell
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i8 acceptassoc
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```
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Notice in the second command, we did not use the devname, again, that is
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_sticky_ so unless we are switching back and forth between character drivers, we
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can just use it once.
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The acceptassoc command, without any arguments, informs the `i8sak` instance to
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accept all association requests. The acceptassoc command also allows you to only
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accept requests from a single device by specifying the extended address with
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option `-e`.
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For instance:
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```shell
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i8 acceptassoc -e DEADBEEF00FADE0B
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```
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But for this example, let's just use the command with no arguments.
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Now, the second device will act as an endpoint device. The i8sak instance
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defaults to being in endpoint mode. Let's refer to the second device as device
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`B`.
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On device B, run:
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```shell
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i8 /dev/ieee0 assoc
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```
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This command attempts to associate with the node at the configured endpoint
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address. If everything is setup correctly, device A should have log information
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saying that a device tried to associate and that it accepted the association. On
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device `B`, the console should show that the association request was successful.
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With all default settings, device B should have been allocated a short address
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of `0x000B`.
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If you are following along with a packet sniffer, you should see something
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similar to the following:
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```
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1) Association Request
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Frame Type - CMD
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Sequence Number - 0
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Dest. PAN ID - 0xFADE
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Dest. Address - 0x000A
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Src. PAN ID - 0xFFFE
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Src. Address - 0xDEADBEEF00FADE0C
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Command Type - Association Request
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1a) ACK
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Frame Type - ACK
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Sequence Number - 0
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2) Data Request
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Frame Type - CMD
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Sequence Number - 1
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Dest. PAN ID - 0xFADE
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Dest. Address - 0x000A
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Src. PAN ID - 0xFFFE
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Src. Address - 0xDEADBEEF00FADE0C
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Command Type - Data Request
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2a) ACK
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Frame Type - ACK
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Sequence Number - 1
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3) Association Response
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Frame Type - CMD
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Sequence Number - 0
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Dest. PAN ID - 0xFADE
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Dest. Address - 0xDEADBEEF00FADE0C
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Src. Address - 0xDEADBEEF00FADE0A
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Command Type - Association Response
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Assigned SADDR - 0x000C
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Assoc Status - Successful
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3a) ACK
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Frame Type - ACK
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Sequence Number - 0
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```
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The default endpoint address can be configured via Kconfig or set dynamically
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using the `set` command.
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Here is how to set the endpoint short address
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```shell
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i8 set ep_saddr 0a:00
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```
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When setting the address, it's important to make sure the endpoint addressing
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mode is configured the way you want: Use `s` for short addressing or `e` for
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extended
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```shell
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i8 set ep_addrmode s
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```
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Device B has now successfully associated with device A. If you want to send data
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from device B to device A, run the following on device B:
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```shell
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i8 tx ABCDEF
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```
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This will immediately (not actually immediate, transaction is sent using CSMA)
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send the frame to device A with frame payload `0xABCDEF`
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Sending data from device A to device B is different. In IEEE 802.15.4, frames
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must be extracted from the coordinator. To prepare the frame, run the following
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command on device A
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```shell
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i8 tx AB
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```
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Because the devmode is PAN Coordinator, the `i8sak` app knows to send the data
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as an indirect transaction. If you were running the `i8sak` app on a device that
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is a coordinator, but not the PAN coordinator, you can force the `i8sak` app to
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send the transaction directly, rather than to the parent coordinator, by using
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the `-d` option.
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**Note**: Currently, the indirect transaction timeout is disabled. This means
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frames must be extracted or space may run out. This is only for the testing
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phase as it is easier to debug when I am not fighting a timeout. Re-enabling the
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timeout may effect the behavior of the indirect transaction features in the
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`i8sak` app.
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To extract the data, run the following command on device `B`:
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```shell
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i8 poll
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```
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This command polls the endpoint (our device A PAN Coordinator in this case) to
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see if there is any data. In the console of device B you should see a Poll
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request status print out.
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