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can-j1939-kickstart: update documentation for testj1939 

testj1939 need to use -B (broadcast) flag to be able to send or receive
broadcast packages.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
pull/175/head
Oleksij Rempel 2019-11-29 13:22:58 +01:00
parent 5d3f8073b2
commit 8cf6353039
1 changed files with 22 additions and 31 deletions
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can-j1939-kickstart.md
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@ -33,7 +33,7 @@ testj1939 can be told to print the used API calls by adding **-v** program argum
Do in terminal 1 Do in terminal 1
./testj1939 -r can0: testj1939 -B -r can0
Send raw CAN in terminal 2 Send raw CAN in terminal 2
@ -59,7 +59,7 @@ is not meant for us and *testj1939* does not receive it.
Binding a can-j1939 socket to a source address will register Binding a can-j1939 socket to a source address will register
allow you to send packets. allow you to send packets.
./testj1939 can0:0x80 testj1939 can0:0x80
Your system had, for a small moment, source address 0x80 assigned. Your system had, for a small moment, source address 0x80 assigned.
@ -67,7 +67,7 @@ Your system had, for a small moment, source address 0x80 assigned.
Terminal 1: Terminal 1:
./testj1939 -r can0:0x80 testj1939 -r can0:0x80
Terminal 2: Terminal 2:
@ -87,37 +87,42 @@ Open in terminal 1:
And to these test in another terminal And to these test in another terminal
./testj1939 -s can0:0x80,0x3ffff testj1939 -B -s can0:0x80 can0:,0x3ffff
This produces **1BFFFF80#0123456789ABCDEF** on CAN. This produces **1BFFFF80#0123456789ABCDEF** on CAN.
Note: To be able to send a broadcast we need to use, we need to use "-B" flag.
### Multiple source addresses on 1 CAN device ### Multiple source addresses on 1 CAN device
./testj1939 -s can0:0x90,0x3ffff testj1939 -B -s can0:0x90 can0:,0x3ffff
produces **1BFFFF90#0123456789ABCDEF** , produces **1BFFFF90#0123456789ABCDEF** ,
### Use PDU1 PGN ### Use PDU1 PGN
./testj1939 -s can0:0x80,0x12345 testj1939 -B -s can0:0x80 can0:,0x12300
emits **1923FF80#0123456789ABCDEF** . emits **1923FF80#0123456789ABCDEF** .
Note that the real PGN is **0x12300**, and destination address is **0xff**. Note that the PGN is **0x12300**, and destination address is **0xff**.
### Use destination address info ### Use destination address info
Since in this example we use unicast source and destination addresses, we do
not need to use "-B" (broadcast) flag.
The destination field may be set during sendto(). The destination field may be set during sendto().
*testj1939* implements that like this *testj1939* implements that like this
./testj1939 -s can0:0x80,0x12345 can0:0x40 testj1939 -s can0:0x80 can0:0x40,0x12300
emits **19234080#0123456789ABCDEF** . emits **19234080#0123456789ABCDEF** .
The destination CAN iface __must__ always match the source CAN iface. The destination CAN iface __must__ always match the source CAN iface.
Specifying one during bind is therefore sufficient. Specifying one during bind is therefore sufficient.
./testj1939 -s can0:,0x12300 :0x40 testj1939 -s can0:0x80 :0x40,0x12300
emits the very same. emits the very same.
@ -129,13 +134,13 @@ __sendto( *peername* )__ , and only one is used.
For broadcasted transmissions For broadcasted transmissions
./testj1939 -s can0:0x80,0x12300 :,0x32100 testj1939 -B -s can0:0x80 :,0x32100
emits **1B21FF80#0123456789ABCDEF** rather than 1923FF80#012345678ABCDEF emits **1B21FF80#0123456789ABCDEF**
Destination specific transmissions Destination specific transmissions
./testj1939 -s can0:0x80,0x12300 :0x40,0x32100 testj1939 -s can0:0x80,0x12300 :0x40,0x32100
emits **1B214080#0123456789ABCDEF** . emits **1B214080#0123456789ABCDEF** .
@ -146,21 +151,7 @@ It makes sometimes sense to omit the PGN in __bind( *sockname* )__ .
J1939 transparently switches to *Transport Protocol* when packets J1939 transparently switches to *Transport Protocol* when packets
do not fit into single CAN packets. do not fit into single CAN packets.
./testj1939 -s20 can0:0x80 :,0x12300 testj1939 -B -s20 can0:0x80 :,0x12300
emits:
18ECFF80#20140003FF002301
This is the first fragment for broadcasted *Transport Protocol*.
_testj1939_ returns before the subsequent packets can leave, and
as the last socket on the system closes, can-j1939 effectively
cleans up all resources. Real-world applications will run like forever,
and will not encounter this side-effect.
Try again, and instruct _testj1939_ to keep the socket open for 1 second.
./testj1939 -w1.0 -s20 can0:0x80 :,0x12300
emits: emits:
@ -178,11 +169,11 @@ First assign 0x90 to the local system.
This becomes important because the kernel must interact in the This becomes important because the kernel must interact in the
transport protocol sessions before the complete packet is delivered. transport protocol sessions before the complete packet is delivered.
./testj1939 can0:0x90 -r & testj1939 can0:0x90 -r &
Now test: Now test:
./testj1939 -s20 can0:0x80 :0x90,0x12300 testj1939 -s20 can0:0x80 :0x90,0x12300
emits: emits:
@ -200,8 +191,8 @@ This overhead scales very good for larger J1939 packets.
### Change priority of J1939 packets ### Change priority of J1939 packets
./testj1939 -s can0:0x80,0x0100 testj1939 -B -s can0:0x80 :,0x0100
./testj1939 -s -p3 can0:0x80,0x0200 testj1939 -B -s -p3 can0:0x80 :,0x0200
emits emits