I think this discussion is not needed in public ... I don't want to listen more... you say I'm a moron and i'm stupid... The question was more do somebody has already see this kind of weird thing = in the microchip datasheet... I did not expect that somebody open the data= sheet and look into and take a day to respond... This is a mailing list, a= nd I know this is for quick answers... thank you for your help. ________________________________ From: Olin Lathrop To: Microcontroller discussion list - Public. Sent: Thursday, May 26, 2011 9:52:12 AM Subject: Re: [PIC] canbus v2.0b extended id filtering RussellMc wrote: >> kris duff wrote: >>> I would like to know if it is possible to filter only the ID >>> partially ( something like bits [0:12] ). > > Olin wrote: >> Yes. That's why there are both masks and filters. Both are well >> explained in the datasheet. > > Olin - > NOT wanting to be "on your case", but this looks from > here like a really non-useful comment and more liable to just make > annoyance and noise than be helpful. To be honest, I didn't read every word of his post. I had a board to finis= h and get off to a customer and then I wanted to get home and plant tomatoes now that it's finally not raining for the first time in 1 1/2 weeks. This post was in the short window while I was running a backup. Yes, I saw he mentioned something about the datasheet, but what he said about it didn't make any sense, and I didn't have time to look it up myself and see what hi= s confusion might be. I have read the same datasheet section myself in great detail when I developed our own low level CAN routines, and found it to be reasonably clear and complete. I got everything working by using the datasheet as my only source of information, so I have a existance proof that all the information is in there. >From a quick glance, it seemed to me the big concept he was missing was th= at there are things called "masks" in addition to the "filters" he mentions. Since the masks are there for precisely what he was asking about ("filter only the ID partially"), it seemed that merely pointing out the existance o= f the masks could be the nudge he needed. The fact that all the information IS in the datasheet can also be useful. Some seem to assume that when they can't get it, the datasheet is at fault. So, in the limited time I had both to read his post and respond to it, I gave him the following information: 1 - There are things called "masks", which are for precisely the purpose he seemed to be asking about. 2 - Despite possible appearances to the contrary, the information IS in the datasheet. If this information is not useful or sufficient, oh well, he can have all his money back. He can also come back and ask more specific and more clear questions if confusion persists. Note that I trimmed his post to just the part I responded to. This was of course for the usual reason of avoiding clutter, but also to make it clear that I wasn't responding to the rest. Frankly, the rest look a rather jumbled mess at first glance. This is another reason I deleted it without comment. You often are the one to say that I should simply not respond when I don't like the way something is written, but now when I did you want me to explain why. First I don't owe anyone, including you, any explanation. Since I'm not being paid, I can chose to not respond to any message or any part of any message as I see fit= , without obligation to justify it. However, since you asked and basically put me on the spot publicly, I feel = I need to waste the time explaining just to defend myself. If you think this is insulting to the OP, note that I silently ignored it and you were the on= e to ask for justification. > " ... but in the datasheet something weird is written : there is a > note telling this register is available in mode 1 and 2 only. But in > the description, there is only description for mode 0 ..." I didn't feel like playing 20 questions guessing which "modes" he was referring to about which part of the hardware. I may remember modes by nam= e or general description. But really, I'm supposed to remember them by their bit field value!!? That's so obviously not supplying meaningful context as to be borderline rude. Yes, that's how I really felt about it, which of course didn't exactly make me want to spend effort elaborating on the answer. He should have been able to understand that others are very unlikely to hav= e read that section of that datasheet so recently to remember such minutia. Besides, he was having a general CAN misconception, so this was all just th= e trees getting in the way of seeing the forest anyway. > He says he's looked in the datasheet, he's quoting material that > doesn't make sense to him, he's asking for help from people with > practical experience. But his quote didn't make sense to me. It seemed to me he was expecting people to do excessive research just to understand what he was talking about. From his apparent lack of understanding of context his readers needed, it seemed to me that getting into a discussion with this guy would be too painful. Yes, I judge people here by the quality of their question. This is then used to decide how much it's worth helping them. This guy didn't completely flunk the test, but got a D or C-. It's my call to make, and I don't have to justify it to anyone. Again, note that I just silently ignored it as you have often advised in the past. I figured if others with more patience than I followed up and he eventually learned how to provide better context, I might jump in and add a few things= .. But as it stood now, my thought process was "this will be too much trouble, no thanks". > He says that he's doing a paper design and can't > try it out with the actual hardware. Lots of people say lots of stuff. My first reaction to that was "that's silly", so I ignored it. Some things are worth helping with, others not, o= r I simply don't feel like it. That's the beauty of email. You can pretend anything you don't want to bother replying to just didn't happen. Again, h= e can have all his money back. > What more would you expect him to have done? Provided better context for what was frankly just babble that would have taken some work to make sense of. > If you know the answer and decided to reply at all why were you not > more helpful? 1 - That's all I had time for that day that post. No apologies for that. 2 - That's what I thought addressed the real problem after a quick read of the post. I still think that's true. > If you decided not to be helpful (which is entirely your right) why > did you not just say nothing. I did exactly that to the majority of the post. Apparently that's not good enough for you either. Another time I might have explained why the rest of his post was mostly babble to me, and you probably would have gotten upset at that. This day for this post I didn't, and now you want my to justify why I didn't. You can't have it both ways. Russell, your second guessing of my posts is getting quite tiresome. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. 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