Segger JLink - Worth it for hobby use ?

[alin_im]

Hey guys,

I am thinking of purchasing a Segger JLink EDU, is it worth it for hobby use ? I have some past experience with MCUs, but I want to get a little bit more serious with them.

My job is not in embedded systems so I will purchase for personal use. I do not have any project in mind to do, so I will just experiment with it until an idea comes.

Do you think I should buy it or just stick with some cheap development platform like Nucleo and don't bother. I think Nucleo already has a build in debugger.

What I find very nice is that it doesn't matter what MCU you are using as long as it is an ARM M and you can program and debug it without the need of having individual programmers for each vendor.

For 60 pounds it is a little bit pricey, but if I am going to focus on this in my free time it may be worth it. What do you think ?

Regards,
Alin

[ataradov]

It all depends on your style of work.

I personally would not get one for $10. But a lot of people think about then as "profesional" for some arbitrary reason.

[filssavi]

The biggest advantage as you mentioned is the cross vendor compatibility is very nice, but It is not the only advantage, often the ICE you find on cheap Dev board are somewhat slow (very slow some times) and they might have less features and more often than not they are just cut down j-link's

[Kjelt]

There is firmware to reprogram an stlink to segger jlink, you have to google it but for €20 for the st link that could be a better deal. However a genuine segger is always preferred IMO.

[stmdude]

Yea, I've had the misfortune of recently being introduced to the Segger J-Links (not the EDU version, the bigger ones).

The hardware seems alright, but their software is utter crap. At least the command-line stuff is, as I haven't tested their IDE integration..

Even if you disregard the softwares lack of documentation, idiotic arguments to the commands (which the debugger could have figured out itself), and other idiosyncrasies, there's very, very little value-add to a JLink compared to a $20 ST-Link, or even a $2 clone of a ST-Link.

Some people get hung up on Seggers "RTT" functionality, which on a powerpoint level looks great. Except, their software suck. As in, their logging-system _looses_ messages.  Hint: The SEGGER_RTT.c files have no atomic functions or locking in place.

Right now, I can only find two good things to say about the Seggers (when they work).
First one: The time it takes to flash is slightly shorter, as they read out the flash, compare and then only writes the changed pages to flash.
Second: Their RTOS integration in the GDBserver is actually pretty convenient.

Oh, and in case you don't already know, the ST-Links (as all SWD DAPs) will work just fine with other vendors chips. You can use it to flash NXP, Nordic, Atmel, etc, etc. As long as they are Cortex-M with an SWD port (or JTAG for that matter), it'll work.

I might have mentioned ST-Link more than a few times here, but that's just because they're very easy to get a hold of. Any other adapter will do the job as well, such as (for example) a CMSIS-DAP.

[tszaboo]

I dont think so. First, you can buy about 5 STM Discovery, or the Nucleo boards for the same price. Or the boards that you like. I also find Jtag to be cumbersome for hobby projects, because of the connector. It is perfectly fine to have a 144 pin huge MCU with dedicated JTAG pins and 4 layer board routing everything nicely, but this is for hobby. The usual cheap demo boards will all have built in USB debug SWD or similar, and no JTAG interface. And that interface is enough for 95% of use cases.

[stmdude]

There is firmware to reprogram an stlink to segger jlink, you have to google it but for €20 for the st link that could be a better deal. However a genuine segger is always preferred IMO.

Well, it comes with a "few" reservations..

• May be used with ARM based ST devices only
• Only debugging on evaluation boards is allowed. Debugging on custom hardware is not supported and not allowed
• No production flash programming support
• Unlimited breakpoints in flash available for evaluation only
• No support is given

[alin_im]

Thank you for the replies, what I have concluded for now is that the best solution is to wait and see what I will need when I will need it.

One last thing, do you think that the eBay clones are worth it (8 pounds instead of 60) or there are garbage ?

Alin

[alin_im]

I do not see myself working with CPUs higher than M4 so I think that the JLINK mini is a much better choice. Do you know if it accepts it up to M4 ?

[hans]

J-LINK EDU Mini is a version of the J-Link EDU in a reduced form factor with identical functionality for Cortex-M based targets.  It has been designed to allow students and educational facilities as well as hobbyists access to top of the line debug probe technology.

I.e. they dropped the 20-pin boxed JTAG header and went for the 10-pin Cortex-M debug only. That is fine for regular SWD usage, no need for trace, etc. It also drops support for some of the older ARM7TDMI cores, which some need the RTCK signal (I think LPC2100 does, not familiar with others). But if you only plan to use modern parts with Cortex m0+ and up, that's not a problem. Actually, I think it's a wicked deal considering it's a tiny debugger for a much better price.

I would probably pick one up along a ST discovery board (or any other brand) anyway. Because with a vendor dev board you're locked in to them, and that's usually bad long term.

For 20$ I wouldn't touch any Ebay knock off. Not worth it.

[alin_im]

Just realized I have a Silicon Zero Gecko https://www.silabs.com/products/development-tools/mcu/32-bit/efm32-zero-gecko-starter-kit dev kit and in its specs says that contains Integrated SEGGER J-Link USB debugger/emulator with debug out functionality  does this means that the 60 pounds device is already integrated into a 30 pounds platform ?

Maybe you can clarify this for me, is this like the STLink which can program only S Labs MCUs ? Or can accept any vendor MCU ? 

[thm_w]

Just realized I have a Silicon Zero Gecko https://www.silabs.com/products/development-tools/mcu/32-bit/efm32-zero-gecko-starter-kit dev kit and in its specs says that contains Integrated SEGGER J-Link USB debugger/emulator with debug out functionality  does this means that the 60 pounds device is already integrated into a 30 pounds platform ?

Maybe you can clarify this for me, is this like the STLink which can program only S Labs MCUs ? Or can accept any vendor MCU ? 

The cost is for the software not the hardware, the hardware is ~$2 of parts. If you care a lot about cost you can look at the mini EDU model already suggested, which is about $20.
I suspect its limited, to test yourself: plug in your dev board, run J-Flash, choose a non-EFM32 part, and select target->connect. It will give you an error message if they've restricted access (most likely did).

[hans]

Just realized I have a Silicon Zero Gecko https://www.silabs.com/products/development-tools/mcu/32-bit/efm32-zero-gecko-starter-kit dev kit and in its specs says that contains Integrated SEGGER J-Link USB debugger/emulator with debug out functionality  does this means that the 60 pounds device is already integrated into a 30 pounds platform ?

Maybe you can clarify this for me, is this like the STLink which can program only S Labs MCUs ? Or can accept any vendor MCU ? 

Yes, on the Giant gecko board I have the J-link debugger circuitry is hidden under the LCD. They have hidden it because I suspect they use a ST part for it 

The functionality is quite extensive in that you can redirect the SWD offboard (but also turn the debugger off and use your own). However I haven't tried hooking it up to any non-Silicon Micro parts.

[mac.6]

Lot of dev boards include debugger that can be flashed as a JLink debugger, most Kinetis parts are like this for example.
It's not an exact EDU version as most are very slow (around 4/8MHz) so advanced debug is limited (like RTT or SystemView usage).
RTT is a fine software, of course you need to provide some support for lock/unlock functions, it is far above uart and doesn't requires swo support. Only their linux support is lacking for the tools.

[alin_im]

Thank you for all your responses, I will try the Jlink EDU mini because it super affordable and I will not see myself using more advanced MCUs then the ones with M4F, meaning that the Jlink EDU is too advanced for my purposes. Also, I think that 4 MHz is enough for my learning purposes, I do not intend to become an ARM guru, but to experiment and have an idea that is beyond using Mbed environment.

[Sal Ammoniac]

Several MCU manufacturers have licensed J-Link firmware from Segger and include it on their own debuggers. Some examples: the NXP LPC-Link 2 and the Infineon XMC Link.

Most of these are better values than a Segger J-Link, and/or include features the J-Link doesn't. For example, an LPC-Link 2 is only $20, and the XMC Link is isolated, which is a $250 add-on board for a Segger J-Link.

[plazma]

You can also direct printf() to the SWO pin. At least with EFM32 chips.

[ElektroQuark]

Ozone is the debugger from SEGGER.
Look at it, you can use it with a J-LINK.

[andyturk]

Ozone is the debugger from SEGGER.
Look at it, you can use it with a J-LINK.

This.

J-Link is worth it because you get to use Ozone. Technically, you're supposed to use one of Segger's hardware dongles with a "license" on it, but Ozone works just fine without that. You just have to acknowledge a dialog when you run it for the first time.

Using the J-Link on-board firmware, you can reflash the debug side of a STM32 disco board to be a J-Link and then debug it with Ozone. For under $20 USD it's a really sweet setup. Grab GCC 6.x from ARM (for free), your favorite text editor and you're good to go.

[Sal Ammoniac]

J-Link is worth it because you get to use Ozone.

What does Ozone do that Segger Embedded Studio doesn't?

[andyturk]

What does Ozone do that Segger Embedded Studio doesn't?

Puts $1800 more dollars in your pocket?

For debugging, Ozone and SES are probably pretty close. I know folks who use SES and like it a lot. For me, I prefer to use emacs for editing and use gmake for builds, so all I need is a debugger. Ozone fits that bill nicely.

[ElektroQuark]

I'm using CodeBlocks as IDE with Ozone for debugging. Nice combo.

[ulix]

There is firmware to reprogram an stlink to segger jlink, you have to google it but for €20 for the st link that could be a better deal. However a genuine segger is always preferred IMO.

Well, it comes with a "few" reservations..

• May be used with ARM based ST devices only
• Only debugging on evaluation boards is allowed. Debugging on custom hardware is not supported and not allowed
• No production flash programming support
• Unlimited breakpoints in flash available for evaluation only
• No support is given

Problem: the Jlink EDU is for education purpose only as well...

[hans]

Just had taken a look at the JLink SystemViewer software. It was easy to integrate into any RTOS, even experimental ones ('it just works'), and it gives a nice level of detail using fairly limited system resources. Combine that with a fast timestamped serial terminal , and overall it's quite nice. Thanks @mac.6 !

1 limitation is the number of events it can record per second. With a 1kB buffer on the chip, it seems to peak out at 500kbit/s of traffic  @ 4000kHz with my JLINK EDU, which is ~16k events/second. Still not bad though considering you get microsecond level timestamping.

Now if only the software a bit more stable... It seems the safest bet is to reset the target chip and replug the Jlink probe upon switching between OpenOCD GDB server and the SystemViewer software. Other the firmware is not properly flashed and you get spontaneous crashes and weird HardFaults.

[Sal Ammoniac]

For debugging, Ozone and SES are probably pretty close. I know folks who use SES and like it a lot. For me, I prefer to use emacs for editing and use gmake for builds, so all I need is a debugger. Ozone fits that bill nicely.

I downloaded and installed Ozone and it seems to work well. I like its interface a lot.

One thing I couldn't find, however, is how to display peripheral registers. It'll display Cortex-M peripheral registers (like the NVIC, MPU, etc.) but I can't find a way to display non-Cortex registers such as for the I2C, SPI, and UART peripherals. The startup sequence asked me what kind of MCU I had (an Infineon XMC4700), so it knows that--is there a way to get Ozone to display these registers? If not, its usefulness to me is nearly zero because debugging driver code without being able to see these registers is a pain in the ass. Sure, I could dump the registers in raw form in the memory display by providing their start address, but all modern debuggers I've used display peripheral registers while interpreting their contents and breaking them down into their individual bit fields.