Hello everyone,
We are having trouble getting tracing to work with our target at full clock speed and would like to understand why, we have an application running on STM32U575 @ 160MHz CPU clock, we also connected the J-Tracer to it using a connector glued next to the uC and short wires (~10mm) to PE2 ... PE6 (pins 1 to 5 on the LQFP100), the GPIO pins are all configured (using a JLinkScript) as AF and at maximum speed, and what we understood from the documentation (Arm trace technical specification - SEGGER Wiki) the trace clock and trace data operate at half the CPU speed, I checked the ST datasheet and the GPIOs we are using should be good up to at least 100MHz, so in theory the trace should be possible with the CPU running at 160MHz and outputting trace data @ 80MHz, or?
- I have tested with the CPU at 160MHz and 2 trace data pins instead of 4, and it works, but the trace buffer overflows every time, as only 2 data lines are too slow for the amount of information.
- I also tested with the CPU at 80MHz and everything works as expected, with trace using all 4 data lines working without problems.
First I would like to confirm that the HW should support this and then, if so, I will need to find out why it is not working, perhaps checking the delays with a fast enough oscilloscope and trying to optimise the distances and parasitic capacitance, any help or tips will be appreciated
Thank you
Gustavo Cardoso
We are having trouble getting tracing to work with our target at full clock speed and would like to understand why, we have an application running on STM32U575 @ 160MHz CPU clock, we also connected the J-Tracer to it using a connector glued next to the uC and short wires (~10mm) to PE2 ... PE6 (pins 1 to 5 on the LQFP100), the GPIO pins are all configured (using a JLinkScript) as AF and at maximum speed, and what we understood from the documentation (Arm trace technical specification - SEGGER Wiki) the trace clock and trace data operate at half the CPU speed, I checked the ST datasheet and the GPIOs we are using should be good up to at least 100MHz, so in theory the trace should be possible with the CPU running at 160MHz and outputting trace data @ 80MHz, or?
- I have tested with the CPU at 160MHz and 2 trace data pins instead of 4, and it works, but the trace buffer overflows every time, as only 2 data lines are too slow for the amount of information.
- I also tested with the CPU at 80MHz and everything works as expected, with trace using all 4 data lines working without problems.
First I would like to confirm that the HW should support this and then, if so, I will need to find out why it is not working, perhaps checking the delays with a fast enough oscilloscope and trying to optimise the distances and parasitic capacitance, any help or tips will be appreciated
Thank you
Gustavo Cardoso