FAQs for NEXUS-AVR32
AVR32 Trace impacts (Nexus-AVR32)
|Which impacts regarding real time behavior must be expected if the Nexus trace is activated?|
As long as just program trace is activated and MCKO is set to CPU clock, no speed impacts must be expected.
In special cases , just Flowerrors may be visible in the trace list window which may cause flow lost in the trace
list. But there is still no speed impact of real time porgram execution.
In case of slower MCKO (1/2, 1/4 etc. CPU clock) and in case of data trace is additionally activated, also no speed
impacts can be recognized. However the trace contents is possibly not usable due to not sufficient or wrong
information from the Nexus cell of the device.
To be able to get correct trace information from the device anyway, there is an overrun control register which allows
either to generate over flow messages or to avoid nexus FIFO overruns.
(Nexus FIFO overruns normally cause unusable trace buffer contents)
This mechanism however, may causes real time program execution impacts for the case, the Nexus FIFO
threaten to overflow. How much it is depends on the user program and if data-rd and/or data-wr
messageging is enabled.
(This is not a problem of the debugger, but of the device)
Breakpoint instruction (Nexus-AVR32)
|Is a breakpoint instruction allowed in the code ?|
Breakpoint instructions are not allowed in code if a debugger is used for debugging.
Without a debugger, a breakpoint instruction is executed as a NOP instruction. In this case, the code will work anyway.
If a debugger is involved , program execution will stop at the breakpoint. The user program will not work.
Information about AVR32 EVBs (Nexus-AVR32)
|Are there modifications of Atmel EVBs for using Nexus trace ?|
To be sure that trace signals on the EVB are really released and available for Nexus trace,
the system offers a disagnostic command. Just enter DIAG 3016 , the result will be displayed
in the Area window.
Possibly for the following EVB's , modifications are needed to be able to use Nexus trace :
• Check if the Push button SW4 and SW5 are really open. ? (PB3 -> MDO4, PB2 -> MDO3).
• Check if the pins 1 till 6 of J17 area really open.
• R32 (0 Ohm) must be removed if U7 is populated. (PB4 is MDO5).
• EVTI : R33 (0 Ohm ) must be removed if U7 is populated.
• PB0 and PB1 are connected to the SD-Card Socket. Remove SD-Card!
• J16 pin 18 must be N/C.
• PA31 (MDO0) is connected to the temperature sensor.
• J16 pin 17 must be N/C.
• Be aware that PA30 (MCKO) is connected to the Photo sensor.
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Last generated/modified: 09-Apr-2019