trice

README

Trice <- TRace Ids C Embedded

Tiny & fast tracer code for embedded device real-time PC logging (trace ID visualization) over any port.

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• github.io/trice/

About

• Printf-like trace macros TRICE and PC trice tool (written in Go) for automatic ID managing & logging.
• Communication without string transfer, just with IDs. Prerequisite: byte transmission to PC, low bandwidth is ok:
  • method does'nt matter:
    UART,
    I²C,
    SPI,
    GPIO,
    RTT,
    CAN,
    LIN, ...
• "log in (a) trice" (S>G)
• Main idea: Logging strings not into an embedded device to display them later on a PC but keep usage comfortable and simple.

TRICE macros for C & C++ code

• Real fast: 12 CPU clocks per (short) trice possible!!!
  • With a 48MHz clock this is 250ns. Light travels about 80 meters in that time.
• TRICE in your code reduces the needed FLASH memory because the instrumentation code is very small (can be less 200 bytes FLASH and about 100 bytes RAM) and no printf library code nor log strings are inside the embedded device anymore.

Possible Use Cases

• Using trice not only for dynamic debugging but also as logging technique is possible and gives the advantage to have very short messages (no strings) for transmission, but keep in mind that the file til.json is the key to read all output if your devices in the field for 10 or more years.
• You can consider TRICE also as a kind of data compression what could be interesting for IoT things, especially NB-IoT, where you have very low data rates.
• Storing trices in FLASH for later log analysis saves memory because a typical TRICE occupies only 4 or 8 bytes.
• Also it is possible to encrypt the trice transfer packets to get a reasonable protection for many cases.
  • This way you can deliver firmware images with encrypted TRICE output only readable with the appropriate key and til.json.
  • XTEA is implemented as one option.
• You can even translate the til.json in different languages, so changing a language is just changing the til.json file.
• Using trice with an RTOS gives the option for detailed task timing analysis. Because of the very short execution time of a trice you could add to the scheduler:

    Trice16i( "tim:@tick %5u ", clock );
    Trice8i( "sig:task %u -> %u\n", previousTaskID, nexTaskID );

The execution of this code block produces totally 8 log bytes to vizualize the output on PC, what looks similar to this for 3 task switches:

First are the PC reception timestamps and after the port info are the used trice ids just for easy location inside the source code. See the diferences between the (blue) ticks in this 3 lines. These are 28 or 36 processor clocks only. The code producing this is:

The same is possible for interrupt timing analysis.

• Mixed case trice macros are short trices and the letter i at the end says inside critical section. (FLEX encoding)
• Trice16( "tim: myFunc %d\n", sysTick ); before and after a function call lets you easy measure the function execution time.
• As graphical vizualisation you could use a tool similar to https://github.com/sqshq/sampler.
• TRICE has intentionally no target timestamps for performance reasons. On the PC you can display the reception timestampts. But you can add own timestamps as parameters for exact embedded time measurements. Having several devices with trice timestamps, network timing measurement is possible.

How it approximately works

For example change the source code line

printf( "MSG: %d Kelvin\n", k );

into

Trice16( "MSG: %d Kelvin\n", k );

trice update (run it automatically in the tool chain) changes it to

Trice16( Id(12345), "MSG: %d Kelvin\n", k );

or (if -addParamCount is used)

Trice16_1( Id(12345), "MSG: %d Kelvin\n", k );

and adds the ID 12345 together with "MSG: %d Kelvin\n" into a trice ID list, a JSON referece file named til.json.

• The 12345 is a randomly or policy generated ID not used so far.
• With the 16 in Trice16 you adjust the parameter size to 16 bit what allows more runtime efficient code compared to 32 or 64.
• The optional appended _1 sets the expected parameter count to 1, allowing a compile time parameter count check.
• During compilation the Trice16[_1] macro is translated to only a 12345 reference and the variable k. The format string never sees the target.

This is a slightly simplified view:

• When the program flow passes the line Trice16( Id(12345), "MSG: %d Kelvin\n", k ); the ID 12345 and the 16 bit temperature value are transfered as one combined 32 bit value into the triceFifo, what goes really fast. Different encodings are possible. The program flow is nearly undisturbed, so TRICE macros are usable also inside interrupts or in the scheduler.
• For visualization a background service is needed. In the simplest case it is just an UART triggered interrupt for triceFIFO reading. Or you can use RTT.
• So the whole target instrumentation are the trice macros, the trice fifo and the UART ISR.
• During runtime the PC trice tool receives the trice as a 4 byte package 0x30 0x39 0x00 0x0e from the UART port.
• The 0x30 0x39 is the ID 12345 and a map lookup delivers the format string "MSG: %d Kelvin\n" and also the format information "TRICE16_1". Now the trice tool is able to execute printf("MSG: %d Kelvin\n", 0x000e); and the full log information is displayed in the MSG color.
• Only the parameter count and size affect encoding size but not the format string length.

trice PC tool

• Manages TRICE macro IDs inside a C or C++ source tree and extracts the strings in an ID-string list during target device compile time.
• Displays TRICE macros like printf() output in realtime during target device runtime. The received IDs and parameters are printed out.
• Can receive trices on several PCs and display them on a remote display server.
• Written in Go, simply usage, no installer, needs to be in $PATH.

Structured Logging?

Right now only event logging is implemented.

According to the design aim "Keep embedded device code small and fast" there is no structuring code inside the target device, but you can add channel information to the trice log strings:

trice32( Id(12345), "Verbose: bla bla")

These can be understood as tags too. But only one tag per trice right now. Look into lineTransformerANSI.go for options or extensions.

Also you can at compile time disable trice code generation on file level with #define TRICE_OFF before including trice.h.

Because one trice consists typically only of 4 to 8 bytes there is usually no need to dynamically switch trices on and off inside the embedded device. This can be done on the display side inside the trice tool with the command line switches -ban or -pick. For example -pick err,wrn disables all output despite error and warning messages. Switching trices on and off inside the target increases the overhead and demands some kind of command interface. If needed, always an if is usable.

The trice tool can also perform further tasks like JSON encoding with additional log infomation and transferring this information to some webserver in the future.

Display server option?

Yes, you can simply start trice ds inside a console, option: third_party/alacritty, locally or on a remote PC and connect with several trice tool instances like with trice log -p COM15 -ds for example.

How to keep ID reference file til.json for a long period?

• Of course git, but it is not forbidden to compile til.json as a ressource into the embedded device and get it later back if you have enough flash memory.

How to start

• Get trice or download latest release assets for your system: Source code and compressed binaries.
• A port to Darwin should be easy possible.

Either use pre-compiled trice binary

• Place the extracted trice binary somewhere in your $PATH.

Or build trice from Go sources

• Install Go.
• Open a console inside the trice directory.
• Check and install:

go vet ./...
go test ./...
go install ./...

Afterwards you should find an executable trice inside $GOPATH/bin/

Running

trice help

Quick target setup

• It is sufficient for most cases just to use the trice32 macro with max 4 parameters as a replacement for printf and to use the default settings.
• Compare the not instrumented test project MDK-ARM_LL_generatedDemo_STM32F030R8-NUCLEO-64 with one of the instrumented test projects in test to see what to to.
  • Recommendation: FLEX encoding
• Or follow these steps for instrumentation information even your target processor is not an ARM (any bit width will do):
  • Install the free STCubeMX.
  • Choose from test examples the for you best fitting project MyExample.
  • Open the MyExample.ioc file with STCubeMX and generate without changing any setting.
  • Make an empty directory MyProject inside the test folder and copy the MyExample.ioc there and rename it to MyProject.ioc.
  • Open MyProject.ioc with STCubeMX, change in projects settings MyExample to MyProject and generate.
  • Now compare the directories MyExample and MyProject to see the trice instrumentation as differences.
• For compiler adaption see triceConfigCompiler.h.
• For hardware adaption see triceUART_LL_STM32

Documentation

No need to read all this stuff - is is just for help and reference.

• Common.md
• TriceEncodings.md
• ID management
• OneWireOption
• SeggerRTT

Support?

Yes please: May be you create a graphical display server, have a cool idea, a port to other hardware, some correction or simply like to ⭐ it. ☺

Cloning the repo

git clone https://github.com/rokath/trice.git