Hello,
I have a J-Link EDU Mini, which I believe should be capable of reaching a maximum JTAG speed of 4 MHz.
Connecting to J-Link via USB...O.K.
Firmware: J-Link EDU Mini V1 compiled Feb 20 2025 16:27:02
Hardware version: V1.00
J-Link uptime (since boot): 0d 06h 07m 14s
S/N: 801055125
License(s): FlashBP, GDB
USB speed mode: Full speed (12 MBit/s)
VTref=3.299V
Connecting at 2 MHz works fine but fails at 4 MHz.
I took two screenshots in my logic analyzer and it is clearly visible that the duty cycle gets worse with higher frequency (it looks ~50/50 at lower frequencies such as 400 kHz). In addition, TCK for 4 MHz setting measures as 3.33 MHz.
I just wanted to check if this is expected behavior.
Many thanks for your help,
Felix