About a year ago I bought a Segger j-Link for farnell for use on a new project using the Cortex M4. It turned up and it all seemed good and I was able to start work on the project. Yesterday I was talking to a colleague and he happened to mention that the newest software had provided him with a firmware upgrade for his unit, this was strange as I had also downloaded the newest version of the software (V6.00e) but my j-link hadn't been offered a firmware upgrade. Looking in to it in more detail we noticed that whilst my colleague's J-link was version 9.2, my j-link purchased several months later was actually only V8, which appears to have not had any firmware upgrades since 2014.

I then wanted to look into what the differences were between the two hardware versions and found UM08001, which on page 34 states that the V8 hardware doesn't work with the Cortex-M4. I was a bit surprised by this as I've been using it with the stm32f4 for the last year and not notice many major problems. The only few things I've noticed are that, when I was playing with the option bytes trying to set the Read protection I ended up with some weird settings being set in the option bytes and the j-link wasn't able to successfully clear the read protection when requested to. The other thing I've noticed is that occasionally the J-link can fail to connect properly to the M4 and to fix this I have to disconnect the J-Link and power cycle the m4. Are these the only issue I'm likely to have or am I going to end up running into some nasty issues later down the line where the j-link can't address certain areas of memory or something?