**** BEGIN LOGGING AT Fri May 20 02:59:59 2016 May 20 09:20:33 how to find beaglebone project ideas May 20 09:21:02 hello May 20 14:11:09 * ZeekHuge reading the data sheets May 20 16:32:07 Hi again!! Does anybody know how to port pru kernel driver to kernel 4.1? May 20 16:33:28 the kernel driver ? name ? May 20 16:33:33 of the driver ? May 20 16:34:02 and what revision of 4.1 ? May 20 16:34:06 kiran4399: ^^ May 20 16:36:19 I meant to say.. porting pru linux kernel driver for linux kernel 4.1 May 20 16:59:36 I guess you are speaking about remoteproc kernel . So, in that case, Its very simple, if you are using 4.1.18 and above, then there is no need to port. If using 4.1.17 and below, you can use https://github.com/ZeekHuge/PRU-framework May 20 16:59:39 kiran4399: ^^ May 20 17:49:55 ds2: Hi ! do you have some time ? May 20 17:50:52 I was looking into the data-sheets, so have understood most of the things in it .. May 20 18:19:49 * ZeekHuge is missing Wormo. May 20 18:27:18 hey May 20 18:27:30 ZeekHuge: whatca need? May 20 18:50:03 hey bradfa are you there? May 20 18:50:57 foreverska, Hey are you there?Just have a doubt May 20 18:51:07 Yup May 20 18:51:51 foreverska, Okay this might sound a little silly May 20 18:51:59 hi chanakya_vc May 20 18:52:13 But I just wanted to know which class of SD cards can you use with BBB? May 20 18:52:20 bradfa ^^ May 20 18:52:32 chanakya_vc: heh, that's not the easiest question :) May 20 18:52:43 chanakya_vc: the class ratings on SD cards do not mean anything, in reality May 20 18:53:21 Okay so no difference between class 10 or class 4? May 20 18:53:32 Spped May 20 18:53:34 chanakya_vc: well, there can be a huge difference, but the class rating won't really give you the whole story May 20 18:53:44 chanakya_vc: one sec, I find a recommendation for you May 20 18:54:26 bradfa,What I understood was that class 10 requires the device that you are working with to have a certain writing and reading speed so May 20 18:54:29 foreverska, ^^ May 20 18:55:05 chanakya_vc: it gets very complicated, for some background you can read https://lwn.net/Articles/428584/ May 20 18:55:10 bradfa,will this do:http://www.flipkart.com/sandisk-ultra-16-gb-microsdhc-class-10-48-mb-s-memory-card/p/itmea5e3xydamg9h?pid=ACCEA5E3GPBQJ9P9&al=5Lm9UKLdfOWgI90oGCOnjMldugMWZuE7sHPMhtl4IOorJwXPvUTTXt80u7XfVRnItNam9VafGr0%3D&ref=L%3A-7250439661111262051&srno=p_2&otracker=from-search May 20 18:55:19 I don't think so... I use Class 10/U1 in beagles all the time. May 20 18:55:38 chanakya_vc: and if you are interested, read the non-spam sent to the flashbench-results mailing list: https://lists.linaro.org/pipermail/flashbench-results/ May 20 18:56:15 bradfa,Okay.I was thinking of buying one and then I got confused because of the class thing. May 20 18:56:31 chanakya_vc: possibly that's a good card, generally the higher end Sandisk cards and Samsung cards are good choices May 20 18:56:51 chanakya_vc: sadly, consumer grade SD cards only are on the market for a year or two before they get new models which will likely behave differently May 20 18:56:58 bradfa, foreverska So any micro SD meant for mobile phones will work right? May 20 18:57:11 chanakya_vc: I have a bunch of Sandisk Ultra Mobile micro-SDHC cards which I like, in 4 GB and 8 GB sizes May 20 18:57:30 chanakya_vc: any card will work, just the performance will vary greatly between a "good" card and a "bad" one May 20 18:57:32 I've never had a problem with a BBB and an SD card. I tend to stick to Samsung or Sandisk C10/UHS1 May 20 18:57:54 bradfa, They are cheap.Always can buy a new one.The one I showed would be around 5 dollars May 20 18:58:06 foreverska, I will search for that one May 20 18:58:10 chanakya_vc: I have these kind (but not 16 GB size, mine are smaller) http://www.flipkart.com/sandisk-ultra-16-gb-sdhc-class-10-80-mb-s-memory-card/p/itme9p55gj7hkhbn May 20 18:58:29 Yea I have half a dozen of those May 20 18:58:32 chanakya_vc: I'm not sure how the newer sandisk ultra cards like you sent the link for a redifferent May 20 18:59:47 bradfa,The difference I see is in the speed.48MB/s vs 80MB/s .Even though both are Class 10 May 20 19:00:01 chanakya_vc: you won't ever see those speeds on a beaglebone :) May 20 19:00:28 bradfa, Okay so it won't matter then : ) : ) May 20 19:00:58 chanakya_vc: what matters for using an SD card is how good the controller is inside the card, how many open write operations can it support at one time. Read the lwn article I linked to May 20 19:03:42 bradfa, I will May 20 19:04:11 chanakya_vc: just if it helps, I always use normal mobile SD cards. And they work great. May 20 19:05:00 ZeekHuge,Okay I am ordering a the cheaper one then :P May 20 19:05:03 ds2: okay so I am following http://cds.linear.com/docs/en/demo-board-manual/dc782A.pdf and http://cds.linear.com/docs/en/datasheet/223876fa.pdf May 20 19:05:07 bradfa ^^ May 20 19:07:10 chanakya_vc: ok. The eMMC on bbb is pretty decent, too. Results of it from flashbench tool: https://lists.linaro.org/pipermail/flashbench-results/2013-January/000353.html and https://lists.linaro.org/pipermail/flashbench-results/2013-February/000355.html May 20 19:08:03 bradfa,might need some help later with the makefile,Zeekhuge was kind enough to show me:https://github.com/ZeekHuge/PRU-framework May 20 19:08:16 bradfa,will go through it : ) May 20 19:08:34 and the part i mentioned is 782A-P, So on quick starter guide (QSG) page 2, the table shows LTC2236 May 20 19:08:50 ds2: ^^ May 20 19:09:39 ds2: so the next Pdf is of LTC2236 (datasheet = dsheet ). May 20 19:10:14 chanakya_vc: ok May 20 19:12:24 bradfa,One more basic question.I used to think that the read and write speed actually used to depend upon the clock cycle.Like in Double Data Rate SDRAM''s we sample at the rising and falling edges of the clock May 20 19:13:08 ds2: now QES page 23 has the circuit. and there is that jumper 3201S-40G1. and i have understood all the pin functions there. But what I am having difficulty with is the Encode clock (QES diagram on page 4) May 20 19:13:44 bradfa, To double to frequency of reading and writing right? May 20 19:14:14 chanakya_vc: yes, with a DDR clocked system you get twice the throughput of the frequency of the clock May 20 19:15:41 chanakya_vc: but, for example on SD cards, the DDR capability is not implemented in the hardware in AM335x, so the fastest your SD card can go is 4 bits wide bus at 52 MHz May 20 19:16:03 er, sorry, 50 MHz May 20 19:16:04 bradfa,So what I don't understand is,that if this depends upon the system clock,how can makers of such hard disks predict the actual data speed w/o knowing the system it's gonna be on? May 20 19:16:12 chanakya_vc: they lie May 20 19:16:13 :) May 20 19:16:18 yes, and the class of the SD card is the MAX speed May 20 19:16:20 chanakya_vc: "benchmarks" are never to believed :) May 20 19:18:50 bradfa, Ohh : ) .Actually I never thought people could lie so openly about their products. May 20 19:20:20 bradfa, So the DDR is only implemented in SDRAM's I believe?And when you say 4 bit wide bus at 50 hz max basically means it can write 4 bits at one time and do this at frequency of 50 hz? May 20 19:25:04 ZeekHuge: have you committed to this board? May 20 19:25:12 that encode clock is going to cause issues May 20 19:25:22 it'll make things complicated :( May 20 19:27:01 ds2: oh ! ah ... May 20 19:27:37 this is the very board that I ordered. May 20 19:27:47 *I mentioned May 20 19:27:57 ZeekHuge: that is the clock input. on every edge of that clock, the ADC will run a sample May 20 19:28:20 problem is the board is trying to be very nice and has added a nice terminated clock input (chip doesn't have that) May 20 19:29:11 so now either you work out what kind of massaging is needed from the PRU to properly drive the buffer (NC7SVU04) or you find another way around it May 20 19:29:27 look at the schematic near the end of the QSG May 20 19:29:54 it isn't fatal, just makes things complicated. Normally, that is a good thing as it gives the chip a much cleaner signal May 20 19:30:57 ZeekHuge: how good are you at understanding voltage dividers, filters, and transmission lines? May 20 19:31:11 and the follow up is - do you have source of SMA adapters :D May 20 19:32:00 voltage dividers : good, filters and transmission lines : a bit less than okay. May 20 19:32:12 yes, I have a voltage generator. May 20 19:32:20 is that what you are asking ? May 20 19:32:41 ZeekHuge: this is what _I_ would do (might get another opinion) - spend about 2-3 hours max to understand what the input circuit is doing May 20 19:32:50 chanakya_vc: there's DDR modes on SD cards, too, since SD card spec v3.00 (I think) May 20 19:33:08 then figure a simple way to convert a 0-3.3V pulse train into something that can drive that input and have it output the right clock May 20 19:33:16 chanakya_vc: but yes, the SD card interface on AM335x maxes out at 50 MHz and 4 bits wide (if you use eMMC, it's an 8 bit wide bus at up to 52 MHz) May 20 19:33:25 chanakya_vc: so best case throughput to an SD card is 25 MB/sec May 20 19:34:08 ZeekHuge: there is some math involved. you'll need to look at the datasheet for the ADC and the buffer to see what each one does/wants May 20 19:34:36 bradfa: you are assuming the interface is transfer limited May 20 19:35:37 ZeekHuge: does what I am saying make sense? May 20 19:36:24 ds2: yes, if you assume the host and device controllers can go faster, which isn't unheard of May 20 19:36:25 ds2: Yes, absolutely ! I was searching the NC7SVU04 buffer May 20 19:36:46 ds2: but that's the very best you can hope for given bbb SoC hardware May 20 19:37:00 bradfa: from what I have see, the limit is more of the ability of the flash media to write May 20 19:37:34 ds2: oh, yes, in real life you are correct, but many eMMC and even some SD can saturate the am335x MMC/SD controller bus for reads May 20 19:38:21 bradfa: from a non scientific sampling (low end, bottom feeder market) - that doesn't seem to be that common May 20 19:38:59 and I am basing this comment on what I have see ignoring the PoS kingston cards that the xM and white shipped with May 20 19:39:02 bradfa,Okay got it : ) Things are a lot clearer now. Although AM335x works at much higher frequency than that.I am assuming software overheads? May 20 19:39:16 ds2: those kingston cards have crap controllers, that is THE bottom of the market May 20 19:39:42 ds2: newer sandisk or samsung high end cards can easily get very high read speeds on big sequential transfers May 20 19:39:53 bradfa: kingston has a range... I donno where circuitco got those... even kingston stuff on amazon (ones that look the same) are better May 20 19:40:24 bradfa: the other thing is - are you assuming continious writes or bursts? the sandisk stuff has huge internal buffers May 20 19:40:26 chanakya_vc: well, the core clock of the CPU on AM335x on the bbb runs at 1 GHz but the MMC/SD controller inside runs slower and the MMC/SD controller (like all other perhiperhals) is connected to the main CPU over a network of buses internal to the chip May 20 19:40:49 ds2: sandisk has some fun SLC cache tricks they play in both their SD cards and USB sticks :) May 20 19:41:02 ds2: they even play fun SLC games in their SSDs May 20 19:41:06 assuming you buy the right grade/branding May 20 19:41:12 ds2: yes, of course :) May 20 19:41:54 bradfa, SSD's==External Hard disks? May 20 19:41:59 but getting back to the original question - IMO - a class 10 can often be faster in many cases May 20 19:42:02 chanakya_vc: solid state disk May 20 19:42:09 just cuz they are forced to use faster flash May 20 19:42:27 ds2: it depends, but generally, for sequential writes on a fat file system, yes May 20 19:43:00 ds2: class system on SD is measured in a typical still camera use mode of operation with FAT appending images which are roughly the same size as the flash erase block size May 20 19:43:16 even w/o a FS, it feels faster May 20 19:43:24 dd'ing images onto them is quicker :D May 20 19:43:32 ds2: :) May 20 19:43:32 (yes, that is sequential to the extreme) May 20 19:43:56 ds2: so long as the controller isn't doing logical addressing for you to hide its garbage collection :) May 20 19:44:15 managed flash is the devil, but it's a devil we're stuck with :) May 20 19:44:41 bradfa, I believe that most of the external hard disks are SSD's.Only the internal ones are not SSD's,they are moving kind right.HDD's? May 20 19:45:18 chanakya_vc: you can buy internal and external disks which are either SSD or spinning rust, I'm not sure where the market is going but I assume SSD will only get more and more popular May 20 19:54:42 * bradfa has to head out, be back on Monday (email if you need me for anything, please) May 20 19:57:34 bradfa, Okay Will do! May 20 20:02:58 ds2,Just wanted to ask you something,I was just trying to understand what you and bradfa were discussing,and so you were saying that brands like kingston depend on MLC ?while Sandisk is based on SLC? May 20 20:03:54 Like SanDisk implements some coded logic in SLC to make it even more faster? May 20 20:06:45 chanakya_vc: sandisk have a very small SLC flash (single level cell) that acts like a cache which the controller writes to as a buffer, so as to improve small write speeds, so that the controller can hide any latencies or slow operations which it is doing on the main big MLC flash May 20 20:07:07 chanakya_vc: it's a little trick that sandisk do to make their devices be faster for most use cases May 20 20:07:15 chanakya_vc: it works pretty well May 20 20:07:20 * bradfa now really actually is leaving :) May 20 20:07:43 bradfa, Okay Thanks for explaining :D **** ENDING LOGGING AT Sat May 21 02:59:58 2016