Hi @ll Microchip offers his new controllers (i.e. dsPIC) with > 40 leads only in the TQFP but not PLCC package. Sockets for TQFP are not reliable. Thus they are no solution. What does that mean? The original PCB cannot longer be used for developement, because sockets are not possible. You have to design a special PCB for that. The only way I found, is to solder the device under test on a special adapter PCB, which fits in a special socket on special designed application PCB. Are there other possibilities? How do you handle this? -- Paul dankt den Helfern, w�nscht jedem viel Spa� im Usenet und gr��t alle, die dies lesen. :-) Thanks to all usenet-helpers and regards.
TQFP handling while developing
Started by ●May 15, 2004
Reply by ●May 16, 20042004-05-16
It should be possible to solder the TQFP package into the application board and develop on that board. Provided you don't blow the DSPIC up, you should not need to remove it for debugging or programming - it's FLASH -Andrew "Paul Rosen" <proxx@lycos.de> wrote in message news:soica0l7e0rgghp8032dhbn1vgrqdm0vm9@4ax.com...> Hi @ll > > Microchip offers his new controllers (i.e. dsPIC) with > 40 leads only > in the TQFP but not PLCC package. Sockets for TQFP are not reliable. > Thus they are no solution. > > What does that mean? The original PCB cannot longer be used for > developement, because sockets are not possible. You have to design a > special PCB for that. > > The only way I found, is to solder the device under test on a special > adapter PCB, which fits in a special socket on special designed > application PCB. > > Are there other possibilities? How do you handle this? > > -- > Paul dankt den Helfern, > w�nscht jedem viel Spa� im Usenet > und gr��t alle, die dies lesen. :-) > Thanks to all usenet-helpers and regards.
Reply by ●May 16, 20042004-05-16
Paul Rosen wrote:> Hi @ll > > Microchip offers his new controllers (i.e. dsPIC) with > 40 leads only > in the TQFP but not PLCC package. Sockets for TQFP are not reliable. > Thus they are no solution. > > What does that mean? The original PCB cannot longer be used for > developement, because sockets are not possible. You have to design a > special PCB for that. > > The only way I found, is to solder the device under test on a special > adapter PCB, which fits in a special socket on special designed > application PCB. > > Are there other possibilities? How do you handle this? >What is the problem in creating an application specific board with everything on that is required for the project ? I do at least a board per project. Debugging is done on the board with an in circuit programmer. Those flash devices do at least 1000 cycles, usually sufficient to solve the problem. Rene -- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
Reply by ●May 16, 20042004-05-16
Paul Rosen wrote:> Rene Tschaggelar <none@none.net> schrieb: > >>What is the problem in creating an application specific board with >>everything on that is required for the project ? > > The problem is, that you do not know before what hardware you need for > a project, even in analog-applications. Software and hardware are > developed together. You have not only to change the software, but also > the hardware. And sometimes you need more than one controller. You > cannot use a new board for maybe every 20 versions, because you cannot > produce TQFD boards yourself. You have to give it away. And only one > PCB is very expensiv and needs much time. If you could produce the PCB > yourself, you make some changes in the layout and get a new one in > half an hour.Either your project planning capabilities and project control are very naff or you are dealing with the cutting (or even bleeding) edge technologies. I will stay with the charitable side and consider that you are on the bleeding edge of developments. This then puts you in the realm of prototyping designs or parts of designs to ensure that you achieve the desired performance.> Further controllers can be damaged, when you have a wild mess of > soldered components. Especially audio-design and picoampere/microvolt > measurings and applications with switched high voltage/currents are > very messed, because her special demands of astral routing. > > Because all that I have to solder the TQFP-processor on a special > ilittle board, which can be inserted in the application developement > board.OK, so you are already using prototyping boardlets with impedance controlled padding. The practice of keeping other component leads very short should still apply. Use a small tipped soldering iron but as large as your dare (this is all about plenty of heat for very short periods of time - mere dabs to connect). If the prototype boardlets do not keep the footprint close to what you need for the final layout the trim these boardlets down further till they nearly fit. Be cognizant of the impedances between layers for your chosen PCB materials.> Further there is another problem: If you have finished developing with > the adapted TQFP Controllers, you have to route the PCB new for the > not adapted series version. And then things change. The audio or the > measuring is wrong now, because disturbed by the controller. Or the > application disturbes the processor now and it crashes.Sounds like youi may need to also consider your decoupling philosophy or your layout toplogies to ensure that you minimise cross-talk and pickup. Take your time doing this.> And what is about emulation, when the processor is soldered into the > board? > > With socketable controllers like PLCC things were much easier. You > could socket it and change it, when damaged. You could produce the > developement versions of PCB yourself. Emulation is no problem: Plug > the emulator into the socket of the controller. And the last > developement version could without problems be the series version. And > if you get problems to leave out the socket in the series version, you > let him be, > > Even for DS you need a controller, which has the same format in the > development and the series version. And for this purpose PLCC was a > good solution. It is the skimpiest format, that is reliable > socketable. But of all things the DS!!-PIC is not available in this > package. Maybe this shows, that mirochip is new in the > (digital-)analog segment and is not familiar with its problems. >Relax a little more and don't get so flustered. Sit and think a bit more about what you are doing and whether there may be better approaches. I haven't followed this thread from the begining but I am sure that pausing for thought to think what others have said here will help you resolve the problems you feel you are having. -- ******************************************************************** Paul E. Bennett ....................<email://peb@a...> Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/> Mob: +44 (0)7811-639972 .........NOW AVAILABLE:- HIDECS COURSE...... Tel: +44 (0)1235-811095 .... see http://www.feabhas.com for details. Going Forth Safely ..... EBA. www.electric-boat-association.org.uk.. ********************************************************************
Reply by ●May 16, 20042004-05-16
Rene Tschaggelar <none@none.net> schrieb:>What is the problem in creating an application specific board with >everything on that is required for the project ?The problem is, that you do not know before what hardware you need for a project, even in analog-applications. Software and hardware are developed together. You have not only to change the software, but also the hardware. And sometimes you need more than one controller. You cannot use a new board for maybe every 20 versions, because you cannot produce TQFD boards yourself. You have to give it away. And only one PCB is very expensiv and needs much time. If you could produce the PCB yourself, you make some changes in the layout and get a new one in half an hour. Further controllers can be damaged, when you have a wild mess of soldered components. Especiallly audio-design and picoampere/microvolt measurings and applications with switched high voltage/currents are very messed, because her special demands of astral routing. Because all that I have to solder the TQFP-processor on a special ilittle board, which can be inserted in the application developement board. Further there is another problem: If you have finished developing with the adapted TQFP Controllers, you have to route the PCB new for the not adapted series version. And then things change. The audio or the measuring is wrong now, because disturbed by the controller. Or the application disturbes the processor now and it crashes. And what is about emulation, when the processor is soldered into the board? With socketable controllers like PLCC things were much easier. You could socket it and change it, when damaged. You could produce the developement versions of PCB yourself. Emulation is no problem: Plug the emulator into the socket of the controller. And the last developement version could without problems be the series version. And if you get problems to leave out the socket in the series version, you let him be, Even for DS you need a controller, which has the same format in the development and the series version. And for this purpose PLCC was a good solution. It is the skimpiest format, that is reliable socketable. But of all things the DS!!-PIC is not available in this package. Maybe this shows, that mirochip is new in the (digital-)analog segment and is not familiar with its problems. -- Paul dankt den Helfern, w�nscht jedem viel Spa� im Usenet und gr��t alle, die dies lesen. :-) Thanks to all usenet-helpers and regards.
Reply by ●May 16, 20042004-05-16
Paul Rosen wrote:> Hi @ll > > Microchip offers his new controllers (i.e. dsPIC) with > 40 leads only > in the TQFP but not PLCC package. Sockets for TQFP are not reliable. > Thus they are no solution. > > What does that mean? The original PCB cannot longer be used for > developement, because sockets are not possible. You have to design a > special PCB for that. > > The only way I found, is to solder the device under test on a special > adapter PCB, which fits in a special socket on special designed > application PCB. > > Are there other possibilities? How do you handle this?Vendors (initially) offer TQFP/SMD only, because that is where the volume business is. It can, and does, change : examples - Cygnal offer selected DIP packages of their MLF production devices - Philips original LPC932 family did not include PLCC package, now, they do. - IIRC, Atmels first data on the AT89C51ED2 also excluded PDIP, but now this is included. So, mention it to Microchip. If it is a 'show stopper', choose another uC... -jg
Reply by ●May 16, 20042004-05-16
Thank you, Paul for your long answer. First I want to say, that my English is not very good. I do not know, whether I understood everything correctly. And do not know, whether I say everything that way, I want it to say. Sorry for this. "Paul E. Bennett" <peb@amleth.demon.co.uk> schrieb:>Either your project planning capabilities and project control are very >naff or you are dealing with the cutting (or even bleeding) edge >technologies. I will stay with the charitable side and consider that >you are on the bleeding edge of developments. This then puts you in the >realm of prototyping designs or parts of designs to ensure that you >achieve the desired performance.This is a problem. I am the only designer in our company. The possibilities are a bit poor. :-( I have to solve every problem without companion and without assistance. What is a naff project contol? Or better: What makes a project control the opposite of naff?>cutting vs bleeding edgeCould you explain that with other words ... my limited English. Sometimes I think, a good equipment makes your thoughts poor. I do not really know, which side is better to switch charitable mode on or off. ;-) But the die of PLCC is too hard. Some effects maybe compensated, but others not.>OK, so you are already using prototyping boardlets with impedance >controlled padding.You are speaking from the little PCBs with the controller on it? Please, tell me more about "impedance controlled padding". The analog section is devided from the digital by both grounds, which goes closed to the controller as possible. The backside (two layers) of the pcb is filled with ground - digital and analog devided to their sections.>The practice of keeping other component leads >very short should still apply. Use a small tipped soldering iron but >as large as your dare (this is all about plenty of heat for very >short periods of time - mere dabs to connect).>If the prototype >boardlets do not keep the footprint close to what you need for the >final layout the trim these boardlets down further till they nearly >fit.Very good!!>Be cognizant of the impedances between layers for your chosen >PCB materials.Isn't it capacity? Please, tell me more.>Sounds like youi may need to also consider your decoupling philosophy >or your layout toplogies to ensure that you minimise cross-talk and >pickup. Take your time doing this.I think I do it. Maybe there are some points, which I do not know.I use two or more grounds. Every section is screened by its own ground. Critical signals are double screened with its own signal, hardened by an amp and then with its ground. Astral wiring as most as possible.. Very critical points (high impedance) are devided by gaps in the PCB or sometimes wired in the air. In extreme situatuations they are sealed from the humidity. I use screen-sheets. I always use kelvin-design for critical measurements. I decouple wires with high and low current. The thermo effect of a soldering joint is annihilated by an inverse one, if disturbing. I take care of the route of every lead. I decouple switched high-voltage leads by resistances near to the switches, to avoid broadcast. This all for PCB route and real wire route. I hope I did not forget anything. Anything more to do? But there is the mechanical process equipment, which is not always asked me. And sometimes the design of the electronic is made by optical aspects. They do not want the electronic to "get cluttered" to different places of the equipment, which would be useful for good decoupling. And sometimes the mechanical eqipment lets you not do, what would be good to avoid crosstalk and pickup. Although this, you have to provide a working design. And that could make problems when changing a working prototype layout because TQFP. But it helps, what you said above.>> And what is about emulation, when the processor is soldered into the >> board?Still unanswered>Relax a little more and don't get so flustered. Sit and think a bit >more about what you are doing and whether there may be better >approaches. I haven't followed this thread from the begining but I >am sure that pausing for thought to think what others have said here >will help you resolve the problems you feel you are having.They said, that I could program the controllers in-curcuit. I know that. This helps only for the software, but not for the hardware. Maybe, I should calm down But that does not change this fact: The die of PLCC makes problems for analog-developement not easier. And I am quite safe, that this bothers not only me. -- Paul dankt den Helfern, w�nscht jedem viel Spa� im Usenet und gr��t alle, die dies lesen. :-) Thanks to all usenet-helpers and regards.
Reply by ●May 16, 20042004-05-16
Jim Granville <no.spam@designtools.co.nz> schrieb:>Vendors (initially) offer TQFP/SMD only, because that is where the >volume business is. > >It can, and does, change : examples >- Cygnal offer selected DIP packages of their MLF production devices >- Philips original LPC932 family did not include PLCC package, now, they > do. >- IIRC, Atmels first data on the AT89C51ED2 also excluded PDIP, but now >this is included. > >So, mention it to Microchip.To the rehabilitation of Microchip I must say, that they offer DIP-dsPICs. But this is only possible until 40 leads. The PLCC would be the better solution, because it is smaller and all the same reliable contactable. And it has got more leads. -- Paul dankt den Helfern, w�nscht jedem viel Spa� im Usenet und gr��t alle, die dies lesen. :-) Thanks to all usenet-helpers and regards.
Reply by ●May 17, 20042004-05-17
Paul E. Bennett wrote:> Paul Rosen wrote: > > >>Rene Tschaggelar <none@none.net> schrieb: >> >> >>>What is the problem in creating an application specific board with >>>everything on that is required for the project ? >> >>The problem is, that you do not know before what hardware you need for >>a project, even in analog-applications. Software and hardware are >>developed together. You have not only to change the software, but also >>the hardware. And sometimes you need more than one controller. You >>cannot use a new board for maybe every 20 versions, because you cannot >>produce TQFD boards yourself. You have to give it away. And only one >>PCB is very expensiv and needs much time. If you could produce the PCB >>yourself, you make some changes in the layout and get a new one in >>half an hour.I do make TQFP boards myself. Now also with 0603 parts. I'm not drilling below 0.7mm or 28mil though. But also that is doable. And when I don't like to drill the many holes, I let the board be done. Depending on the required services I can get 1 dm^2 for 60 Euro or even less withing 3 weeks or even less. Rene
Reply by ●May 17, 20042004-05-17
Paul Rosen wrote:> Rene Tschaggelar <none@none.net> schrieb: > > Further there is another problem: If you have finished developing with > the adapted TQFP Controllers, you have to route the PCB new for the > not adapted series version. And then things change. The audio or the > measuring is wrong now, because disturbed by the controller. Or the > application disturbes the processor now and it crashes.Careful design ...> > And what is about emulation, when the processor is soldered into the > board? > > With socketable controllers like PLCC things were much easier. You > could socket it and change it, when damaged. You could produce the > developement versions of PCB yourself. Emulation is no problem: Plug > the emulator into the socket of the controller. And the last > developement version could without problems be the series version. And > if you get problems to leave out the socket in the series version, you > let him be,I never used an emulator. They were to expensive to start with and meanwhile I have debugging techniques that are sufficient. Rene -- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
