Forums

JTAG wiggler

Started by lear...@gmail.com September 19, 2006
I am new to embedded programming and I am working on MPC8xx. What
exactly is JTAG wiggler and how will it help me with the development? I
tried to find info on it and most groups say that it speeds up
development process. Thanks in advance....

<learnfpga@gmail.com> wrote in message 
news:1158675929.818166.290350@b28g2000cwb.googlegroups.com...
>I am new to embedded programming and I am working on MPC8xx. What > exactly is JTAG wiggler and how will it help me with the development? > I > tried to find info on it and most groups say that it speeds up > development process. Thanks in advance....
Google for Macraigor Wiggler. JTAG allows a direct interface to the heart of the processor and access to its pins so, with a suitable programmer you can program your target board but alos see what is happening within it as the program is running.
Tom Lucas wrote:
> <learnfpga@gmail.com> wrote in message > news:1158675929.818166.290350@b28g2000cwb.googlegroups.com... > >I am new to embedded programming and I am working on MPC8xx. What > > exactly is JTAG wiggler and how will it help me with the development? > > I > > tried to find info on it and most groups say that it speeds up > > development process. Thanks in advance.... > > Google for Macraigor Wiggler.
First of all thanks for the response. I looked at that and the data sheet also but did not make much sense.
> > JTAG allows a direct interface to the heart of the processor and access > to its pins so, with a suitable programmer you can program your target > board but alos see what is happening within it as the program is > running.
So for example I have a simple SPI driver for target board using MPC8xx but I am waiting for another board which will interface with my target board. Till then will this wiggler help me to understand what the program is doing and if its doing what it is supposed to do? Thanks once again....
learnfpga@gmail.com wrote:

> So for example I have a simple SPI driver for target board using MPC8xx > but I am waiting for another board which will interface with my target > board. Till then will this wiggler help me to understand what the > program is doing and if its doing what it is supposed to do? Thanks > once again....
not likely, a wiggler is a very poor (but very cheap) debugging tool, it's for downloading, reading and writing data, setting breakpoints, it debugs sort of like a print statement in software
steve wrote:
> learnfpga@gmail.com wrote: > > > So for example I have a simple SPI driver for target board using MPC8xx > > but I am waiting for another board which will interface with my target > > board. Till then will this wiggler help me to understand what the > > program is doing and if its doing what it is supposed to do? Thanks > > once again.... > > not likely, a wiggler is a very poor (but very cheap) debugging tool, > it's for downloading, reading and writing data, setting breakpoints, it > debugs sort of like a print statement in software
I have also found it to be really slow. -Isaac
<learnfpga@gmail.com> wrote in message
news:1158677699.071357.170000@i42g2000cwa.googlegroups.com...
> > Tom Lucas wrote: >> <learnfpga@gmail.com> wrote in message >> news:1158675929.818166.290350@b28g2000cwb.googlegroups.com... >> >I am new to embedded programming and I am working on MPC8xx. What >> > exactly is JTAG wiggler and how will it help me with the >> > development? >> > I >> > tried to find info on it and most groups say that it speeds up >> > development process. Thanks in advance.... >> >> Google for Macraigor Wiggler. > > First of all thanks for the response. I looked at that and the data > sheet also but did not make much sense.
They never do until you find out what you wanted to know some other way ;-)
>> JTAG allows a direct interface to the heart of the processor and >> access >> to its pins so, with a suitable programmer you can program your >> target >> board but also see what is happening within it as the program is >> running. > > So for example I have a simple SPI driver for target board using > MPC8xx > but I am waiting for another board which will interface with my target > board. Till then will this wiggler help me to understand what the > program is doing and if its doing what it is supposed to do? Thanks > once again....
There are much better JTAG probes out there than the wiggler but they do cost a bit more (&#2013266083;99 for Rowley's CrossLink and IIRC about &#2013266083;300 for Segger's J-Link but the prices are on their websites). The better probers use USB interface rather than the parallel port because sometimes quite a bit of data needs to be moved about. I think the reason the data sheet is not much use to you is because you are not too sure what the probe is for. The first thing you can do with a probe is download your software into your target board. Then, if you have debugging software then you can run that code on your target and the probe gives you the power to stop and start the target, set breakpoints (i.e. stop when a line of code is reached in the program), examine the contents of registers and memory and also to step through your code line by line. The debugging software will most likely be a part of your compiler and not of the Wiggler itself. The Wiggler will come with drivers that will allow your debugger to communicate with it but, once you have that set up, it shouldn't matter too much what type of probe you have - it is just a link to the target. If you don't have a debugger then you will have very little that you can do with the probe - I don't know what compiler you are using so I can't say more on that. You might even be using an assembler. For your SPI application then (assuming you have a debugger) then you can set a breakpoint after your routine to initialise the SPI interface to allow you to stop and check all the appropriate registers have the values you expect in them. You can then set breakpoints in your send and recieve functions so that you can see when and if data is being sent or received and if that data is what you expect. It will help you to determine if you are at fault or the other guy. Basically, once you see the possibilities of seeing which line of code is being executed and what the target is doing then you will quickly think of your own places in the code you want to test. The difference in more expensive probes comes when you want to move large chunks of data or keep log of data as it moves through the processor. Some will put breakpoints into flash as well - which not all probes can do.
<learnfpga@gmail.com> wrote in message 
news:1158677699.071357.170000@i42g2000cwa.googlegroups.com...
> > Tom Lucas wrote: >> <learnfpga@gmail.com> wrote in message >> news:1158675929.818166.290350@b28g2000cwb.googlegroups.com... >> >I am new to embedded programming and I am working on MPC8xx. What >> > exactly is JTAG wiggler and how will it help me with the >> > development? >> > I >> > tried to find info on it and most groups say that it speeds up >> > development process. Thanks in advance.... >> >> Google for Macraigor Wiggler. > > First of all thanks for the response. I looked at that and the data > sheet also but did not make much sense.
They never do until you find out what you wanted to know some other way ;-)
>> JTAG allows a direct interface to the heart of the processor and >> access >> to its pins so, with a suitable programmer you can program your >> target >> board but also see what is happening within it as the program is >> running. > > So for example I have a simple SPI driver for target board using > MPC8xx > but I am waiting for another board which will interface with my target > board. Till then will this wiggler help me to understand what the > program is doing and if its doing what it is supposed to do? Thanks > once again....
There are much better JTAG probes out there than the wiggler but they do cost a bit more (&#2013266083;99 for Rowley's CrossLink and IIRC about &#2013266083;300 for Segger's J-Link but the prices are on their websites). The better probers use USB interface rather than the parallel port because sometimes quite a bit of data needs to be moved about. I think the reason the data sheet is not much use to you is because you are not too sure what the probe is for. The first thing you can do with a probe is download your software into your target board. Then, if you have debugging software then you can run that code on your target and the probe gives you the power to stop and start the target, set breakpoints (i.e. stop when a line of code is reached in the program), examine the contents of registers and memory and also to step through your code line by line. The debugging software will most likely be a part of your compiler and not of the Wiggler itself. The Wiggler will come with drivers that will allow your debugger to communicate with it but, once you have that set up, it shouldn't matter too much what type of probe you have - it is just a link to the target. If you don't have a debugger then you will have very little that you can do with the probe - I don't know what compiler you are using so I can't say more on that. You might even be using an assembler. For your SPI application then (assuming you have a debugger) then you can set a breakpoint after your routine to initialise the SPI interface to allow you to stop and check all the appropriate registers have the values you expect in them. You can then set breakpoints in your send and recieve functions so that you can see when and if data is being sent or received and if that data is what you expect. It will help you to determine if you are at fault or the other guy. Basically, once you see the possibilities of seeing which line of code is being executed and what the target is doing then you will quickly think of your own places in the code you want to test. The difference in more expensive probes comes when you want to move large chunks of data or keep log of data as it moves through the processor. Some will put breakpoints into flash as well - which not all probes can do.
"Tom Lucas" <news@REMOVE_auto_THIS_flame_TO_REPLY.clara.co.uk> wrote in 
message news:1158681622.27293.1@proxy02.news.clara.net...

Sorry, I hate duplicated posts but poxy Outlook promised that it wasn't 
able to send the first one.

At least I'm not replying to my own posts.

Oh... 


Excellent Book:

Embedded system design on a shoestring : acieving high performance with
a limited budget / Lewin Edwards

Covers the use of the Macraigor JTAG wiggler!

Why don't you come and join my new group:
http://groups.google.com/group/realtime_signal_and_control

Frank

Tom Lucas wrote:
> <learnfpga@gmail.com> wrote in message > news:1158677699.071357.170000@i42g2000cwa.googlegroups.com... > > > > Tom Lucas wrote: > >> <learnfpga@gmail.com> wrote in message > >> news:1158675929.818166.290350@b28g2000cwb.googlegroups.com... > >> >I am new to embedded programming and I am working on MPC8xx. What > >> > exactly is JTAG wiggler and how will it help me with the > >> > development? > >> > I > >> > tried to find info on it and most groups say that it speeds up > >> > development process. Thanks in advance.... > >> > >> Google for Macraigor Wiggler. > > > > First of all thanks for the response. I looked at that and the data > > sheet also but did not make much sense. > > They never do until you find out what you wanted to know some other way > ;-) > > >> JTAG allows a direct interface to the heart of the processor and > >> access > >> to its pins so, with a suitable programmer you can program your > >> target > >> board but also see what is happening within it as the program is > >> running. > > > > So for example I have a simple SPI driver for target board using > > MPC8xx > > but I am waiting for another board which will interface with my target > > board. Till then will this wiggler help me to understand what the > > program is doing and if its doing what it is supposed to do? Thanks > > once again.... > > There are much better JTAG probes out there than the wiggler but they do > cost a bit more (=A399 for Rowley's CrossLink and IIRC about =A3300 for > Segger's J-Link but the prices are on their websites). The better > probers use USB interface rather than the parallel port because > sometimes quite a bit of data needs to be moved about. > > I think the reason the data sheet is not much use to you is because you > are not too sure what the probe is for. > > The first thing you can do with a probe is download your software into > your target board. Then, if you have debugging software then you can run > that code on your target and the probe gives you the power to stop and > start the target, set breakpoints (i.e. stop when a line of code is > reached in the program), examine the contents of registers and memory > and also to step through your code line by line. > > The debugging software will most likely be a part of your compiler and > not of the Wiggler itself. The Wiggler will come with drivers that will > allow your debugger to communicate with it but, once you have that set > up, it shouldn't matter too much what type of probe you have - it is > just a link to the target. > > If you don't have a debugger then you will have very little that you can > do with the probe - I don't know what compiler you are using so I can't > say more on that. You might even be using an assembler. > > For your SPI application then (assuming you have a debugger) then you > can set a breakpoint after your routine to initialise the SPI interface > to allow you to stop and check all the appropriate registers have the > values you expect in them. You can then set breakpoints in your send and > recieve functions so that you can see when and if data is being sent or > received and if that data is what you expect. It will help you to > determine if you are at fault or the other guy. > > Basically, once you see the possibilities of seeing which line of code > is being executed and what the target is doing then you will quickly > think of your own places in the code you want to test. > > The difference in more expensive probes comes when you want to move > large chunks of data or keep log of data as it moves through the > processor. Some will put breakpoints into flash as well - which not all > probes can do.
<frank.agee@gmail.com> wrote in message 
news:1158817601.688191.184490@h48g2000cwc.googlegroups.com...

Tom Lucas wrote:
> <learnfpga@gmail.com> wrote in message > news:1158677699.071357.170000@i42g2000cwa.googlegroups.com... > > > > Tom Lucas wrote: > >> <learnfpga@gmail.com> wrote in message > >> news:1158675929.818166.290350@b28g2000cwb.googlegroups.com...
> >> >I am new to embedded programming and I am working on MPC8xx. What > >> > exactly is JTAG wiggler and how will it help me with the > >> > development?
<Top post fixed to avoid the swoop of the Falcon...> <snip some more> Excellent Book: Embedded system design on a shoestring : acieving high performance with a limited budget / Lewin Edwards Covers the use of the Macraigor JTAG wiggler! Why don't you come and join my new group: http://groups.google.com/group/realtime_signal_and_control What does this group offer that isn't covered by comp.realtime, comp.arch.embedded or sci.engr.control? I refuse to use google so how am I to access it?