FAQs for NEXUS-MAC


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PDF document ( 72KB / 07-Sep-2016 )


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Target Aux Port Connector Location and Extension Cables

Ref: 0162
Can I use a longer extension cable?

Often customer ignore the warnings regarding the locaction of the aux port connector and regarding additional extension cables between the debugger and the target.
This can cause a lot of trouble, especially for high speed applications. We strongly recommend to place the aux port connector as close as possible nearby the CPU. As closer as better. Take care about the signal trace length.
Do not connect aux port signals to other connectors than the aux port connector and prevent signal stubs. Connect a proper termination to the signals coming from the probe, close to the CPU. Signals from the CPU to the probe should not be terminated.
One can add 0 Ohm resistors in line of each Nexus signal close to the CPU. If necessary 0 Ohm can be replaced by a better value.
The debugger does normally not need any pull-up or pull-down, except for reset. Care must just be taken just for non-Nexus signals. Bear in mind that the target needs possibly a pull-up or pull-down for certain signals if the debugger is not connected.
Pay attention about the recommendations of the device manufacturer regarding the circuitry around the Nexus Aux port.
We also recommend to use no other extension cables than the cables which come with the debugger.
If possible do not use additional cables at all. Longer cables may work, but must not. It is the customers risk to use longer once as recommended. We can not guarantee proper operation.

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MAC71/72 Front Connector Pinout (Nexus-MAC71/72)

Ref: 0204
I can't find the pinout of the MAC71/72 front connector?

Here it is:
                          Front view
              +--------------------------------+
              |  2  4  6  8 10 12 14 16 18 20  |
              |                                |
              |  o  o  o  o  o  o  o  o  o  o  |
              |  o  o  o  o  o  o  o  o  o  o  |
              |                                |
              |  1  3  5  7  9 11 13 15 17 19  |
              +--------------    --------------+


              GND : 1,2,3,5,7,8,9,10,11,13,15,16
              IN0 :  4
              IN1 :  6
              OUT0: 12
              OUT1: 14
              VBUF: 17,19
              3.3V: 18
              5V  : 20

          Jumper setting for 3.3 V target:  17--18
          Jumper setting for   5 V target:  19--20


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Nexus Data Trace (NEXUS-MAC71/72)

Ref: 0141
Why can I not get data trace working?

MAC71xx devices offer Nexus Class 2+ capabilities. Class 2+ does not include data trace messaging.
MAC72xx devices offer Nexus Class 3+ capabilites. This allows also data trace messaging.
Take care that you have the right device selected in System window.

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Nexus EVB MAC71/72 (NEXUS-MAC71/72)

Ref: 0202
Are there special settings for Motorola's MAC71/72xx EVBs?

Make sure the SW1 switch 3 (XCLKS) is in OFF position.
It came up that the board may not work properly with the debugger if the low power Pierce oszillator is activated.

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Unsecure MAC71/72xx (Nexus-MAC71/72)

Ref: 0345
How can I open the device if I have secured it unintentionally ?

If the device has been secured unintentionally, it can be unsecured by a special sequence. Refer to the programming examples in the folder \demo\ARM\Flash\ in e.g. MAC71x1.cmm .

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Dual-port Access to Internal Flash (NEXUS-MAC71XX)

Ref: 0148
Why does the dual-ported data dump to internal flash space fail?

The Nexus debugger does not have access to the processor's read only, tightly coupled instruction flash port in dual port mode.
To access this internal flash memory using dual-port access (internal nexus registers), it is necessary to access these adresse through the AIPS module. The base address for this AIPS access to Flash programming interface is 0xfc10_0000.
Example: Access the 0x30000, must be 0xfc130000.

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Flash Programming Issue (NEXUS-MAC71XX)

Ref: 0135
Why does the flash cannot be reprogrammed after changing the PLL settings?

The Flash Clock Divider Register (CFMCLKD) in the MAC71xx can only be programmed a single time.
During the integrated debugger based Flash programming, the CFMCLKD register must be set according to the current processor speed (fsys). If a different MCU clock speed is selected after writing the CFMCLKD register, the CFMCLKD register can not be re-written to the new correct value. Before Flash programming takes place, the tool checks if the Flash clock is within a specified range. If not, the following error message occurs.
    "Correct FLASH programming timing can not be achieved"
In this case, the AREA window provides more information about the current mismatch.

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JTAG-port Clock (NEXUS-MAC71XX)

Ref: 0160
What is the right speed for the JTAG port?

The max. JTAG Clock can be 1/8 to 1/6 of the CPU Clock.
If one starts with 8 MHz, set JTAG clock to 1.25 MHz. It can be changed after the CPU has been speed up.

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Nexus EVB (NEXUS-MAC71XX)

Ref: 0142
Why is the Nexus trace on PortE only sometimes working on the Motorola EVB, despite the same jumper settings?

Check if J17 of the Motorola EVB has been removed. If the jumper is still in, it depends on the position of the potentiometer rotor RV1, if the trace works or not. If it is turned to one or the other limit, MCKO stucks at high or low and the trace will not work. If it is in middle position, the trace may work.
In any case, J17 must be removed for proper operation.

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Watchpoint Behavior (NEXUS-MAC71XX)

Ref: 0140
Why do I sometimes get instruction watchpoint messages more times than expected ?

This could be caused by instruction prefetches.
For an instruction watchpoint, a watchpoint event is generated whenever there is a match between the WP control registers and the value on the address bus whether the address is being executed or just prefetched.




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Last generated/modified: 22-Sep-2016