Datasheet

CAN: Controller Area Network Lab using ST STM32 Cortex-M processors. www.keil.com

PC Tracing: Program Counter samples…

1. Open Debug/Debug Settings and click on the Trace tab. Unselect EXCTRC and on Data R/W sample.

2. Select Periodic. Click OK and click RUN. Double-click in the Trace Records window to clear it.

3. Program samples will now be displayed with a timestamp in both CPU cycles and the time in seconds.

TIP: In this example every 16,384

PC is displayed. PC Samples are useful as they can give good indication where your

CPU is spending its time. Use ETM trace with a ULINKpro if you need to see every instruction executed for advanced

program flow debugging, Code Coverage, Execution Profiling or Performance Analysis.

1. Open Debug/Debug Settings and unselect PC

Samples. They consume a great deal of the SWV

bandwidth. They are best left off if you are not

using them. Click on Close.

Watch and Memory windows: Updated in real-time…

The STM32F400 is an ARM Cortex-M4 processor which incorporates CoreSight debugging technology. CoreSight provides

a means to update the µVision Watch and Memory windows without stealing CPU cycles to do so.

TIP: In addition, you are able, in real-time, to insert values into the Memory window. Right click on the memory location

you want to change, select Modify Memory, enter the new value and press OK.

Recall we have a structure can_msg that contains the CAN frame information. We have two instances of this: CAN_TxMsg

and CAN_RxMsg which are arrays for each of the two CAN controllers.

1. Click on RUN and confirm the CAN values val_Tx and val_Rx are still changing in Watch 1.

2. In a Watch window, double-click on <Enter expression> and enter CAN_TxMsg. Repeat with CAN_RxMsg.

3. In CAN_RxMsg, open to display [0] and data[0]. Note this value changes while the program is running.

4. In CAN_TxMsg, open to display [1] and data[0]. Note this value changes while the program is running.

5. In a memory window, enter &CAN_TxMsg[1].data and press Enter. You will see the appropriate memory locations

change value as the program runs.

6. Stop the program and exit Debug mode.

TIP: Note you can enter these variables when the program is still

running. You can also highlight, drag and drop or right click on a

variable and select Add varname to…

TIP: CoreSight debug technology with Cortex-M processors enables

you to set/unset hardware breakpoints while the program is running.

This finishes a partial demonstration of the Serial Wire Viewer trace

feature of Cortex-M processors. Visit

UUwww.keil.comUU for more

information concerning the Serial Wire Viewer interface in Cortex-M

processors.