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ARM7/LPC21xx debugging capabilities

Discussion in 'Embedded' started by Oliver Betz, Oct 16, 2004.

  1. Oliver Betz

    Oliver Betz Guest

    Hello All,

    reading some of the specs I'm still not completely sure about the
    debugging capabilities of a LPC21xx.

    Can I access memory "non intrusive" while the program is executing
    (like BDM in the 68HC(S)12 or the HCS08?)?

    Or does a memory read always interrupt program execution for some

    If "non intrusive" is possible: is this a standard feature of

    Any general hints about good debuggers?

    Links to web sites about this topic also welcome.

    Thanks in advance,

    Oliver Betz, Oct 16, 2004
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  2. It depends? If you are using JTAG, I think you are access memory while
    the program is running. If you are using a monitor, then no.
    Richard F. Man, Oct 16, 2004
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  3. reading some of the specs I'm still not completely sure about the
    Have a look at


    or post your question there. There are a lot of experts which (i think) can
    help you !


    Martin Maurer, Oct 16, 2004
  4. Oliver Betz

    Schwob Guest

    Hi Oliver,

    the LPC21xx has two debugging interfaces. One is called JTAG and
    allows most things that BDM can do. This is supported by many
    debuggers, such as Keil, IAR, ... but also by the emulator vendors
    like Nohau, Hitex, Ashling (and many others) support this device via
    JTAG and the second option which is called ETM (embedded trace
    macrocell). This option allows real-time, non-intrusive codetrace.
    ETM requires an additional 9 pins which will not be availble for I/O
    if you use them for debugging. By the way, it seems that Philips is
    more serious about debugging options than e.g. Atmel or ST
    Mircoelectronics with their ARM7 devices. All three offer JTAG but
    only Philips offers trace capability with ETM. For more questions
    about the LPC2000 family the user group in Yahoo is an excellent
    source of information. You can find it here:

    Greetings an Schwob in the US
    p.s. comparing the LPC21xx to the HCS08 is like comparing a BMW
    5-series M to a Ford Taurus (similar to a Mondeo in Europe). Both are
    similar in size and can transport 5 people but the performance is VERY
    different. Luckily the price difference in the microcontrollers does
    not exist if you compare similar memory sizes.
    Schwob, Oct 16, 2004
  5. Oliver Betz

    Oliver Betz Guest

    but I didn't find any information about accessing memory during
    program execution.

    hmm, 9 additional pins is pretty much. But I need only variable access
    most times.

    I will ask there.
    certainly, I only wanted to compare the debug interface capabilities.
    The LPC21xx could be an alternative to the HCS12 I'm using at the

    The Motorola BDM background memory access is a really nice feature in
    small embedded applications, because I can watch the state of my
    program without debug code (well, maybe make some variables global).

    BTW, I never used a HCS08, only HC08 (cheap, small) and HC(S)12
    because a HCS12 has a better performance/price ratio.
    hmm, too much software in modern cars. Could be I have to buy a Lada
    next time <g>.

    Oliver Betz, Oct 16, 2004
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