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Build status main:
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Build status, Devel branch:
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Latest Changes:
This is the development branch for V2.00 which includes parallel trace support as well as all the SWO goodness that Orbuculum has always offered. ORBTrace (the FPGA trace interface) has now been moved into its own separate repository as it's grown considerably and really needs its own identity. History for orbtrace until the split point is maintained here for provenance purposes, but new work is now done over in the new location.
The CHANGES file now tells you what's been done when.
Orbuculum now has an active Discord channel at https://discord.gg/P7FYThy . Thats the place to go if you need interactive help.
An Orbuculum is a Crystal Ball, used for seeing things that would be otherwise invisible. A nodding reference to (the) BlackMagic (debug probe), BMP.
You can find information about using this suite at Orbcode.
*** ORBTrace Mini is now available for debug and realtime tracing. Go to Orbcode for more info. ***
For the current development status you will need to use the Devel branch. Fixes are made on main and Devel.
The code is in daily use now and small issues are patched as they are found. The software runs on both Linux and OSX and the whole suite is working OK on most workloads. Any bugs found now will be treated as high priority issues. Functional enhancements will also be folded in as time permits. A contribution offering a build for windows is in progress but isn't yet available.
Orbuculum is a set of tools for decoding and presenting output flows from the Debug pins of a CORTEX-M CPU. Originally it only used the SWO pin but it now also supports hardware for parallel tracing through ORBtrace. Numerous types of data can be output through these pins, from multiple channels of text messages through to Program Counter samples. Processing these data gives you a huge amount of insight into what is really going on inside your CPU. The tools are all mix-and-match according to what you are trying to do. The current set is;
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orbuculum: The main program which interfaces to the trace probe and then issues a network interface to which an arbitary number of clients can connect, by default on TCP/3443. This is used by a base interface to the target by other programmes in the suite. Generally you configure this for the TRACE tool you're using and then you can just leave it running and it'll grab data from the target and make it available to clients whenever it can. Note that some debug probes can now create an orbuculum-compatible interface on TCP/3443, and then you can connect the rest of the suite to that directly, without using the orbuculum mux itself.
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orbfifo: The fifo pump: Turns a trace feed into a set of fifos (or permanent files).
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orbcat: A simple cat utility for ITM channel data.
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orbdump: A utility for dumping raw SWO data to a file for post-processing.
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orbmortem: A post mortem analysis tool (needs parallel trace data).
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orbtop: A top utility to see what's actually going on with your target. It can also provide dot and gnuplot source data for perty graphics.
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orbstat: An analysis/statistics utility which can produce KCacheGrind input files. KCacheGrind is a very powerful code performance analysis tool.
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orbtrace: The fpga configuration bitstream maker to support parallel trace operation.
A few simple use cases are documented in the last section of this document, as are example outputs of using orbtop to report on the activity of BMP while emitting SWO packets.
The data flowing from the SWO pin can be encoded either using NRZ (UART) or RZ (Manchester) formats. The pin is a dedicated one that would be used for TDO when the debug interface is in JTAG mode.
The data flowing from the TRACE pins is clocked using a separate TRACECLK pin. There can be 1-4 TRACE pins which obviously give you much higher bandwidth than the single SWO.
Whatever it's source, orbuculum takes this data flow and makes it accessible to tools on the host PC. At its core it takes the data from the source, decodes it and presents it on a network interface. The Orbuculum suite tools don't care if the data originates from a RZ or NRZ port, SWO or TRACE, or at what speed....that's all the job of the interface.
At the present time Orbuculum supports eleven devices for collecting trace from the target;
- the Black Magic Debug Probe (BMP)
- the SEGGER JLink
- generic USB TTL Serial Interfaces
- FTDI High speed serial interfaces
- OpenOCD (Add a line like
tpiu config internal :3443 uart off 32000000to your openocd config to use it.) - PyOCD (Add options like
enable_swv: True,swv_system_clock: 32000000to yourpyocd.ymlto use it.) - The ice40-HX8K Breakout Board for parallel trace
- The ECPIX-5 ECP5 Breakout Board for parallel trace
- Anything capable of saving the raw SWO data to a file
- Anything capable of offering SWO on a TCP port
- ORBTrace Mini
Information about using each individual interface can be found in the
docs directory. gdb setup files for each device type can be found in the Support directory. You'll find
example get-you-going applications in the Orbmule repository including
gdbinit scripts for OpenOCD, pyOCD and Blackmagic Probe Hosted.
When using SWO Orbuculum can use, or bypass, the TPIU. The TPIU adds (a small amount of) overhead
to the datastream, but provides better synchronisation if there is corruption
on the link. To include the TPIU in decode stack, provide the -t
option on the command line. If you don't provide it, and the ITM decoder sees
TPIU syncs in the datastream, it will complain and barf out. This is deliberate
after I spent two days trying to find an obscure bug 'cos I'd left the -t option off. You can have multiple
channels to the -t option, which is useful when you've got debug data in one stream and
trace data in another.
Beware that in parallel trace the TPIU is mandatory, so therefore so is the -t option. It can be stripped either
by individual applications or the orbuculum mux. When its stripped by the mux the data are made available on
consecutive TCP/IP ports...so -t 1,2 would put stream 1 data out over TCP port 3443 and stream 2 over 3444, by default.
When in NRZ mode the SWO data rate that comes out of the chip must match the rate that the debugger expects. On the BMP speeds of 2.25Mbps are normal, TTL Serial devices tend to run a little slower but 921600 baud is normally acheivable. On BMP the baudrate is set via the gdb session with the 'monitor traceswo xxxx' command. For a TTL Serial device its set by the Orbuculum command line. Segger devices can normally work faster, but no experimentation has yet been done to find their max limits, which are probably it's dependent on the specific JLink you are using. JLink-Pro and JTrace devices appear to work up to 50MHz. YMMV. We haven't really found the limits of ORBTrace Mini yet.
Generally speaking, you will need to configure the target device to output SWD or parallel data. You can either do that through program code, or through magic incantations in gdb. The gdb approach is more flexible and the program code version is grandfathered. It's in the support directory if you want it...but I would advice you take the gdb script and turn it into code manually, that is maintained and the code in the support directory will eventually rust...only use it for guidance.
In the support directory you will find a script gdbtrace.init which contains a
set of setup macros for the SWO functionality. Full details of how to set up these
various registers are available from Arm and
you've got various options for the type of output generated, its frequency and it's content.
Using these macros means you do not need to change your program code to be able to use facilities like orbtop. Obviously, if you want textual trace output, you've got to create that in the program!
Information about the contents of this file can be found by importing it into your
gdb session with source gdbtrace.init and then typing help orbuculum. Help on the
parameters for each macro are available via the help system too (e.g. help enableSTM32SWO).
In general, you will configure orbuculum via your local .gdbinit file. Several example files are
also in the Support directory. There you will find a gdbtrace.init file for 'regular' gcc
use, and a gdbtrace_withwith.init file for use with recent versions of gdb that support
the with syntax. The functionality of both is identical, but the with syntax allows it
to be used more easily with non-C languages like Rust...unfortunately that syntax isn't
supported on older versions of gdb.
Anyway, generically, a configuration looks like this;
source Support/gdbtrace.init <---- Source the trace specific stuff
target extended-remote /dev/ttyACM0 <-
monitor swdp_scan <-
file ofiles/firmware.elf <-
attach 1 <---- Connect to the target
set mem inaccessible-by-default off <-
set print pretty <-
load <---- Load the program
start <---- and get to main
# ---------- Using Stm32F1 as debuggee---------------------------
enableSTM32SWO <*--- turn on SWO output pin on CPU
# ----------ALTERNATIVELY, for Stm32F4 as debugge----------------
enableSTM32SWO 4 <*--- turn on SWO output pin on CPU
# ----------END OF ALTERNATIVE-----------------------------------
# ---------- EITHER, IF USING A BLUEPILL-------------------------
monitor traceswo 2250000 <*--- wakeup tracing on the probe
prepareSWO SystemCoreClock 2250000 1 0 <*--- Setup SWO timing (Bluepill case)
# ----------ALTERNATIVELY, FOR GENUINE BMP-----------------------
monitor traceswo <*--- Enable BMP traceswo output
prepareSWO ConfigCoreClock 200000 0 1 <*--- Setup SWO timing (BMP case)
# ----------END OF ALTERNATIVE-----------------------------------
dwtSamplePC 1 <-
dwtSyncTap 3 <-
dwtPostTap 1 <-
dwtPostInit 1 <-
dwtPostReset 15 <-
dwtCycEna 1 <---- Configure Data Watch/Trace
ITMId 1 <-
ITMGTSFreq 3 <-
ITMTSPrescale 3 <-
ITMTXEna 1 <-
ITMSYNCEna 1 <-
ITMEna 1 <---- Enable Instruction Trace Macrocell
ITMTER 0 0xFFFFFFFF <---- Enable Trace Ports
ITMTPR 0xFFFFFFFF <---- Make them accessible to user level code
Alternatively, if you're using parallel trace via the ice40 remove the lines marked <*- above and replace them with the following;
enableSTM32TRACE <---- Switch on parallel trace on the STM32
prepareTRACE 4 <---- Set up the TPIU for 4 bit output (or 2 or 1)
...be careful to set the trace width to be the same as what you've configured on the FPGA. While
we're here it's worth mentioning the startETM command too, that outputs tracing data. That is
needed for orbmortem.
- libusb-1.0
Note that objdump is also required. By default the suite will run arm-none-eabi-objdump but another binary or pathname can be
subsituted via the -O option.
The command line to build the Orbuculum tool suite is;
make
You may need to change the paths to your libusb files, depending on how well your build environment is set up.
A udev rules files is included in Support/60-orbcode.rules
Install this to /etc/udev/rules.d to grant access to orbcode hardware, if required.
Recipie instructions courtesy of FrankTheTank;
brew install libusb
and finally;
export LDFLAGS="-L/usr/local/opt/binutils/lib"
export CPPFLAGS="-I/usr/local/opt/binutils/include"
The command line options for Orbuculum are available by running
orbuculum with the -h option. Orbuculum is just the multiplexer, the
fifos are now provided by orbfifo. This is a change to the previous
way the suite was configured where the fifos were integrated into orbuculum itself.
Simply start orbuculum with the correct options for your trace probe and then you can start of stop other utilities as you wish. A typical command to run orbuculum would be;
ofiles/orbuculum -m 100
In this case, because no source options were provided on the command line, input will be taken from a Blackmagic probe USB SWO feed, or from an ORBTrace mini if it can find one. It will start the daemon with a monitor reporting interval of 100mS. Orbuculum exposes TCP port 3443 to which network clients can connect. This port delivers raw TPIU frames to any client that is connected (such as orbcat, orbfifo or orbtop). The practical limit to the number of clients that can connect is set by the speed of the host machine....but there's nothing stopping you using another one on the local network :-)
Information about command line options can be found with the -h
option. Orbuculum itself is specifically designed to be 'hardy' to probe and
target disconnects and restarts (y'know, like you get in the real
world). In general the other programs in the suite will stay alive while
orbuculum itself is available. The intention being to give you useful information whenever it can get
it. Orbuculum does not require gdb to be running, but you may need a
gdb session to start the output. BMP needs traceswo to be turned on
at the command line before it capture data from the port, for example.
For orbuculum, the specific command line options of note are;
-a [serialSpeed]: Use serial port and set device speed.
-h: Brief help.
-m: Monitor interval (in mS) for reporting on state of the link. If baudrate is specified (using -a) and is greater than 100bps then the percentage link occupancy is also reported.
-o [filename]: Record trace data locally. This is unfettered data directly from the source device, can be useful for replay purposes or other tool testing.
-p [serialPort]: to use. If not specified then the program defaults to Blackmagic probe.
-s [address]:[port]: Set address for explicit TCP Source connection, (default none:2332).
-t x,y,...: Remove TPIU formatting and issue streams x, y etc over incrementing IP port numbers.
The easiest way to use the output from orbuculum is with one of the utilities
such as orbfifo. This creates a set of fifos or permanent files in a given
directory containing the decoded streams which apps can exploit directly. It also has
a few other tricks up it's sleeve like filewriter capability. It used to be integrated into
orbuculum but seperating it out splits the trace interface from the user space utilities, which
is a Good Thing(tm).
A typical command line would be;
orbfifo -b swo/ -c 0,text,"%c" -v 1
The directory 'swo/' is expected to already exist, into which will be placed a file 'text' which delivers the output from swo channel 0 in character format. Multiple -c options can be provided to set up fifos for individual channels from the debug device. The format of the -c option is;
-c ChannelNum,ChannelName,FormatString
ChannelNum is 0..31 and corresponds to the ITM channel. The name is the one that will appear in the directory and the FormatString can present the data using any printf-compatable formatting you prefer, so, the following are all legal channel specifiers;
-c 7,temperature,"%d \260C\n"
-c 2,hexAddress,"%08x,"
-c 0,volume,"\l%d\b\n"
Be aware that if you start making the formatting or screen handling too complex its quite possible your machine might not keep up...and then you will loose data!
While you've got orbfifo running a further fifo hwevent will be found in
the output directory, which reports on events from the hardware, one event per line as follows (note that
the order of these has changed);
0,[Status],[TS]: Time status and timestamp.1,[EventType],[ExceptionNumber]: Hardware exception. Event type is one of [Enter, Exit, Resume].2,[PCAddr]: Report Program Counter Sample.3,[DWTEvent]: Report on DWT event from the set [CPI,Exc,Sleep,LSU,Fold and Cyc].4,[Comp],[RW],[Data]: Report Read/Write event.5,[Comp],[Addr]: Report data access watchpoint event.6,[Comp],[Ofs]: Report data offset event.7: Currently unused.8,[Status],[Address]: ISYNC event.
The command line options are;
-b [basedir]: for channels. Note that this is actually just leading text on the channel
name, so if you put xyz/chan then all ITM software channels will end up in a directory
xyz, prepended with chan. If xyz doesn't exist, then the channel creation will
fail silently.
-c [Number],[Name],[Format]: of channel to populate (repeat per channel) using printf formatting.
-e: When reading from file, terminate when file exhausts, rather than waiting for more data to arrive.
-f [filename]: Take input from specified file (CTRL-C to abort from this).
-h: Brief help.
-i [channel]: Set Channel for ITM in TPIU decode (defaults to 1). Note that the TPIU must
be in use for this to make sense. If you call the GenericsConfigureTracing
routine above with the ITM Channel set to 0x7f then the TPIU will be bypassed. If you do
not have this set correctly and you're using the TPIU you will not see any data at all.
-l [port]: Set listening port for the incoming connections from clients.
-m: Monitor interval (in mS) for reporting on state of the link. If baudrate is specified (using -a) and is greater than 100bps then the percentage link occupancy is also reported.
-n: Enforce sync requirement for ITM (i.e. ITM needs to issue syncs)
-P: Create permanent files rather than fifos - useful when you want to use the processed data later.
-s [address]:[port]: Set address for Source connection, (default localhost:3443).
-t: Use TPIU decoder. This will not sync if TPIU is not configured, so you won't see
packets in that case.
-v: Verbose mode 0==Errors only, 1=Warnings (Default) 2=Info, 3=Full Debug.
-w [path] : Enable filewriter functionality with output in specified directory (disabled by default).
orbcat is a simple utility that connects to orbuculum over the network and outputs data from various ITM HW and SW channels that it finds. This output is sent to stdout so the program is very useful for providing direct input for other utilities. There can be any number of instances of orbcat running at the same time, and they will all decode data independently. They all get a seperate networked data feed. A typical use case for orbcat would be to act as a stdin for another program...an example of doing this to just replicate the data delivered over ITM Channel 0 would be
orbcat -c 0,"%c"
...note that any number of -c options can be entered on the command line, which
will combine data from those individual channels into one stream. Command line
options for orbcat are;
-c [Number],[Format]: of channel to populate (repeat per channel) using printf
formatting. Note that the Name component is missing in this format because
orbcat does not create fifos.
-e: When reading from file, terminate when file exhausts, rather than waiting for more data to arrive.
-f [filename]: Take input from specified file (CTRL-C to abort from this).
-h: Brief help.
-i [channel]: Set Channel for ITM in TPIU decode (defaults to 1). Note that the TPIU must
be in use for this to make sense. If you call the GenericsConfigureTracing
routine above with the ITM Channel set to 0 then the TPIU will be bypassed.
-n: Enforce sync requirement for ITM (i.e. ITM needsd to issue syncs)
-s [server]:[port]: to connect to. Defaults to localhost:3443 to connect to the orbuculum daemon. Use localhost:2332 to connect to a Segger J-Link, or whatever other combination applies to your source.
-t: Use TPIU decoder. This will not sync if TPIU is not configured, so you won't see
packets in that case.
-v: Verbose mode.
Orbtop connects to orbuculum over the network and samples the Program Counter to identify where the program is spending its time. By default it will update its statistical output once per second. For code that matches to a function the the source file it will totalise all of the samples to tell you how much time is being spent in that function. Any samples that do not match to an identifiable function are reported as 'Unknown'.
As with Orbcat there can be any number of instances of orbtop running at the same time, which might be useful to perform sampling over different time horizons. A typical invocation line for orbtop would be;
orbtop -e ~/Develop/STM32F103-skel/ofiles/firmware.elf
...the pointer to the elf file is always needed for orbtop to be able to recover symbols from.
One useful command line option for orbtop (and indeed, for the majority of the rest of the suite) is -s localhost:2332, which will connect directly to any source you might have exporting SWO data on its TCP its port, with no requirement for the orbuculum multiplexer in the way.
Command line options for orbtop are;
-c [num]: Cut screen output after number of lines.
-d [DeleteMaterial]: to take off front of filenames (for pretty printing).
-D: Switch off C++ symbol demangling (on by default).
-e: Set elf file for recovery of program symbols. This will be monitored and reloaded if it changes.
-E: Include exception (interrupt) measurements.
-g [LogFile]: Append historic records to specified file on an ongoing basis.
-h: Brief help.
-i [channel]: Set Channel for ITM in TPIU decode (defaults to 1). Note that the TPIU must
be in use for this to make sense. If you call the GenericsConfigureTracing
routine above with the ITM Channel set to 0 then the TPIU will be bypassed.
-I [Interval]: Set integration and display interval in milliseconds (defaults to 1000 mS)
-j [filename]: Output to file in JSON format (or screen if is '-')
-l: Aggregate per line rather than per function
-n: Enforce sync requirement for ITM (i.e. ITM needs to issue syncs)
-o [filename]: Set file to be used for output history
-r <routines>: Number of lines to record in history file
-s [server]:[port]: to connect to. Defaults to localhost:3443
-t: Use TPIU decoder. This will not sync if TPIU is not configured, so you won't see
packets in that case.
-v: Verbose mode.
Its worth a few notes about interrupt measurements. orbtop can provide information about the number of times an interrupt is called, what its maximum nesting is, how many 'execution ticks' it's active for and what the spread is of those. Here's a typical combination output for a simple system;
98.25% 1911 ** SLEEPING **
0.25% 5 uart_xmitchars
0.20% 4 up_serialin
0.10% 2 up_doirq
0.10% 2 up_interrupt
0.10% 2 up_restoreusartint
0.10% 2 uart_pollnotify
0.10% 2 uart_write
0.10% 2 nxsem_post
-----------------
99.30% 1932 of 1945 Samples
Ex | Count | MaxD | TotalTicks | AveTicks | minTicks | maxTicks
----+----------+-------+-------------+------------+------------+------------
11 | 1 | 1 | 263 | 263 | 263 | 263
15 | 100 | 1 | 10208 | 102 | 100 | 210
53 | 210 | 1 | 44752 | 213 | 97 | 479
[V-TH] Interval = 1002mS / 7966664 (~7950 Ticks/mS)
The top half of this display is the typical 'top' output, the bottom half is a table of
active interrupts that have been monitored in the interval. Note that outputs are
given in terms of 'ticks', and the number of cpu cycles that correspond to a tick
is set by ITMTSPrescale. You will also need to set dwtTraceException`` and ITMTSEna``` to be able to use this output mode.
To use orbmortem you must be using a parallel trace source such as ORBTrace Mini, and it must be
configured to stream parallel trace info (clue; the startETM option).
The command line options of note are;
-a: Don't use alternate address encoding. Select this if decodes don't seem to arrive correctly. You can discover if you need this option by using the describeETM command inside the debugger.
-b [Length]: Set length of post-mortem buffer, in KBytes (Default 32 KBytes)
-c [command]: Set command line for external editor (0.000000 = filename, % = line). A few examples are;
* emacs; `-c emacs "+%l %f"`
* codium/VSCode; `-c codium -g "%f:%l"`
* eclipse; `-c eclipse "%f:%l"`
-D: Switch off C++ symbol demangling
-d [String]: Material to delete off front of filenames
-e [ElfFile]: to use for symbols and source
-E: When reading from file, terminate at end of file rather than waiting for further input
-f [filename]: Take input from specified file rather than live from a probe (useful for ETB decode)
-s [Server:Port]: to use
-t [channel]: Use TPIU to strip TPIU on specfied channel (normally best to let orbuculum handle this
Once it's running you will receive an indication at the lower right of the screen that it's capturing data. Hitting H will hold the capture and it will decode whatever is currently in the buffer. More usefully, if the capture stream is lost (e.g. because of debugger entry) then it will auto-hold and decode the buffer, showing you the last instructions executed. You can use the arrow keys to move around this buffer and dive into individual source files. Hit the ? key for a quick overview of available commands.
A whole chunk of work has gone into making sure the dataflow over both the SWO link and parallel Trace is reliable....but it's pretty dependent on the debug interface itself. The TL;DR is that if the interface is reliable then Orbuculum will be. There are factors outside of our control (i.e. the USB bus you are connected to) that could potentially break the reliabilty but there's not too much we can do about that since the SWO link is unidirectional (no opportunity for re-transmits). The following section provides evidence for the claim that the link is good;
A test 'mule' sends data flat out to the link at the maximum data rate of 2.25Mbps using a loop like the one below;
while (1)
{
for (uint32_t r=0; r<26; r++)
{
for (uint32_t g=0; g<31; g++)
{
ITM_SendChar('A'+r);
}
ITM_SendChar('\n');
}
}
100MB of data (more than 200MB of actual SWO packets, due to the encoding) was sent from the mule via a BMP where the output from swolisten chan00 was cat'ted into a file;
cat swo/chan00 > o
....this process was interrupted once the file had grown to 100MB. The first and last lines were removed from it (these represent previously buffered data and an incomplete packet at the point where the capture was interrupted) and the resulting file analysed for consistency;
sort o | uniq -c
The output was;
126462 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
126462 BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
126462 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
126462 DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD
126461 EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
126461 FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
126461 GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
126461 HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
126461 IIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
126461 JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ
126461 KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK
126461 LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL
126461 MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
126461 NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
126461 OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
126461 PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
126461 QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ
126461 RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR
126461 SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
126461 TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
126461 UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU
126461 VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV
126461 WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW
126461 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
126461 YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY
126461 ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
(On inspection, the last line of recorded data was indeed a 'D' line).
SWO gives you a number of powerful new capabilities in your debug arsenal. Here are a few examples....if you have more to add please send me an email.
The easiest and most obvious use of SWO is to give you multi-channel debug capability. By adding multiple '-c' definitions to the orbuculum comand line you can create multiple fifos which will each emit data of interest. So, for the simple case of two distinct serial streams, something like the following will suffice;
-c 0,out0,"%c" -c 1,out1,"%c"
...this will create two fifos in your output directory, out0 and
out1, each with distinct output data. By default the CMSIS provided
ITM_SendChar routine only outputs to channel0, so you will need a
new routine that can output to a specified channel. Something like;
static __INLINE uint32_t ITM_SendChar (uint32_t c, uint32_t ch)
{
if ((CoreDebug->DEMCR & CoreDebug_DEMCR_TRCENA_Msk) && /* Trace enabled */
(ITM->TCR & ITM_TCR_ITMENA_Msk) && /* ITM enabled */
(ITM->TER & (1ul << c) ) ) /* ITM Port c enabled */
{
while (ITM->PORT[c].u32 == 0);
ITM->PORT[c].u8 = (uint8_t) ch;
}
return (ch);
}
Now, this works perfectly for chars, but you can also write longer
values into the transit buffer so if, for example, you wanted to write
32 bit values from a calculation, just update the routine to take
int32_t and change the channel definition to be something more like
-c 4,calcResult,"%d".
It gets more complicated when you want to mix output from
individual channels together. In this circumstance you can either
write a bit of script to merge the channels together, or you can use
orbcat to do the same thing from the command line. So if, for
example, you wanted to merge the text from channel0 with the 32 bit values
from channel 4, an orbcat line such as this would do the job;
orbcat -c 0,"%c" -c 4,"\nResult=%d\n"
...its obvious that the formatting of this buffer is completely dependent on the order in which data arrive from the target, so you might want to put some 'tags' or differentiators into each channel to keep them distinct - a typical mechanism might be to use commas to seperate the flows into different columns in a CSV file.
Orbuculum will place fifos for any defined channels (plus the hardware event channel) in the specified output directory. It will simulteneously create a TCP server to which an arbitary number of clients can connect. Those clients each decode the data flow independently of orbuculum, so you can present the data from the target simulteneously in multiple formats (you might log it to a file while also processing it via a plot routine, for example). You can also use the source code for orbcat or orbtop as the basis for creating your own specific decoders (and I'd really appreciate a copy to fold into this suite too please!).
Orbtop is an example client to orbuculum which processes the PC sampling information to identify what routines are running at any point in time. This is essential information to understand what your target is actually doing and once you've got this data you'll find you become addicted to it! Just running orbtop with the details of your target binary is enough for orbtop to do its magic (along with information about the configuration of the incoming SWO stream, of course);
orbtop -t -i 9 -a -e firmware.elf
orbtop can aggregate per function or per program line. By default it aggregates
per function but to work per-line just add the -l option...usually that gives you
too much information though.
The amount (and indeed, presence) of sample data is set by a number of configuration options. These can be set from program code, but it's more flexible to set them from gdb. The main ones are;
dwtSamplePC: Enable or disable Program Counter sample generationdwtPostTap: Set the count rate for the PC interval counter at either bit 6 or bit 10 of the main CPU clock.dwtPostInit: set the initial value for the PC interval counter (this defines when the first sample is taken....you've got to be pretty precise if this is important to you!).dwtPostReset: Set the reload value for the PC Interval Counter (higher values = slower counting).dwtCycEna: Enable the cycle counter input (i.e. switch the whole thing on). You won't get far without this set!
The maximum speed at which you can generate samples is defined by the
speed of your SWO connection but, with a 72MHz CPU, the slowest
settings (dwtPostTap 1 and dwtPostReset 15) still generate about
4000 samples per second, so you will get useful information at that
level of resolution. There is a risk that you could miss frequent, but
short, routines if you're running too slow, so do vary the speeds to
make sure you get consistent results...on the other hand running too
fast will lead to flooding the SWO and potentially missing other
important data such as channel output. You do not need to restart
orbuculum or orbtop in order to change the parameters in gdb - just
CTRL-C, change, and restart. With a setting of dwtPostReset 1 there
are no overflows when using a async interface at 2.25Mbps, which equates
to 35200 Program Counter samples per second.
Here's a typical example of orbtop output for a Skeleton application based on FreeRTOS with USB over Serial (CDC) support. This table is updated once per second;
97.90% 4308 ** Sleeping **
1.25% 55 USB_LP_CAN1_RX0_IRQHandler
0.20% 9 xTaskIncrementTick
0.13% 6 Suspend
0.09% 4 SysTick_Handler
0.06% 3 Resume
0.06% 3 __WFI
0.04% 2 vTaskSwitchContext
0.04% 2 TIM_Cmd
0.02% 1 prvAddCurrentTaskToDelayedList
0.02% 1 xTaskResumeAll
0.02% 1 vTaskDelay
0.02% 1 PendSV_Handler
0.02% 1 __ISB
0.02% 1 taskIn
0.02% 1 statsGetRTVal
0.02% 1 taskOut
-----------------
4400 Samples
orbtop can also generate graph output. You will find utilities to support this for
gnuplot in the Support directory. Just start orbtop with the option -o <filename>
to generate the output data and then run Support/orbtop_plot to generate the output.
By default it generates pdf graphs once per second, but that's easily changed.
Orbuculum was pointed at a a BMP instance (running on a 72MHz STM32F103C8) both with and without SWO running in asynchronous mode at 2.25Mbps.
Firstly, without SWO;
26.96% 1186 gdb_if_update_buf
23.23% 1022 stm32f103_ep_read_packet
21.82% 960 gdb_if_getchar_to
6.66% 293 cdcacm_get_config
6.54% 288 platform_timeout_is_expired
5.61% 247 usbd_ep_read_packet
4.86% 214 platform_time_ms
3.90% 172 cdcacm_get_dtr
0.13% 6 _gpio_clear
0.06% 3 gpio_set_mode
0.04% 2 swdptap_turnaround
0.04% 2 swdptap_seq_out
0.02% 1 swdptap_bit_in
0.02% 1 swdptap_bit_in
0.02% 1 swdptap_turnaround
0.02% 1 platform_timeout_set
-----------------
4399 Samples
...and then, with SWO running (note that in this second case the
sample frequency had to be increased to be able to see the impact,
which is reflected in dma1_channel5_isr and to a much lesser degree
in trace_buf_drain). When this trace was taken the target
was emitting nearly 18000 PC samples per second, encoded in TPIU
frames.
18.17% 3198 stm32f103_ep_read_packet
17.35% 3054 gdb_if_getchar_to
15.05% 2648 gdb_if_update_buf
11.02% 1940 usbd_ep_read_packet
9.24% 1627 platform_time_ms
9.07% 1597 platform_timeout_is_expired
7.93% 1396 cdcacm_get_dtr
4.78% 842 cdcacm_get_config
4.72% 831 dma1_channel5_isr
1.52% 268 usb_copy_to_pm
0.45% 80 stm32f103_poll
0.17% 31 trace_buf_drain
0.06% 12 usb_lp_can_rx0_isr
0.05% 9 gpio_set_mode
0.03% 7 swdptap_turnaround
0.03% 7 swdptap_turnaround
0.03% 7 _gpio_clear
0.03% 7 usbd_poll
0.03% 6 swdptap_seq_out_parity
0.02% 5 swdptap_seq_out
0.02% 4 swdptap_seq_in_parity
0.01% 3 adiv5_swdp_low_access
0.01% 2 swdptap_bit_in
0.01% 2 swdptap_bit_out
0.01% 2 _gpio_set
(Anthing < 0.01% removed)
-----------------
17594 Samples
As Karl Palsson pointed out in Issue #4 on github, all of the support tools just need a stream of 'clean' trace data. Normally that is provided by the network connection that orbuculum exports, but you can also use something like netcat to generate the stream for orbuculum or its clients. For example, from a file that is written to via something like openocd;
> tail -f swo.dump.log | nc -v -v -l 9999 -k
and then;
> ./ofiles/orbuculum -g 9999 -b md/ -c 0,text,"%c"
However, that's probably over-complicated now...just use the orbuculum -s option to hook to any source that is pumping out clean SWO data. This information is just left here to show the flexibilities you have got available.