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11 years, 2 months ago.
combine SDfilesystem with USBMSD_SD
I have the SDfilesystem and the USBMSB_SD hello worlds working separately on my KL25z.
Could someone give me some tips on combining the 2 in one application? Ie like the LPC1768 does with local file system?
Import programUSBMSD_SD_HelloWorld_FRDM-KL25Z
USBMSD_SD HelloWorld for FRDM-KL25Z
- All functions names are compatible with the fat filesystem library. So you can imagine using your own class with
- USBMSD and the fat filesystem library in the same program. Just be careful because there are two different parts which
- will access the sd card. You can do a master/slave system using the disk_status method.
in the comments is telling me what to do....
could someone explain a little more how this is done?
I'd really like to combine this with the USBHID as well to communicate with my PC program with USB packets...
1 Answer
11 years, 2 months ago.
anyone? Still playing with it. I can compile with both the SDfileSystem and USBMSD_SD added and included it seems.
USBMSD_SD sdm(PTD2, PTD3, PTD1, PTD0); SDFileSystem sd(PTD2, PTD3, PTD1, PTD0, "sd");
do I absolutely need to combine these into one class?? It is surprising that nobody has implemented this already as it is just like the standard mbed localfilesystem...
???? help ???
posted by tap tap 13 Jun 2013tried again using: USBMSD_SD::USBMSD_SD(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) : FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs)
and defining the class with multiple inheritance.
class USBMSD_SD : public USBMSD , public FATFileSystem { public:
It compiles, but crashes when trying to access the SDcard if I am attempting a write via FATFilesystem. If I try just the sd.disk_initialize() it won't crash but come up with the "No Disk, or could not.... Didn't get a response from the disk... Set 512-byte block timed out.
posted by tap tap 13 Jun 2013That seems to me like the correct place to start. Sadly I don't have an SDCard holder, so hard to help with this. I assume this is without a USB cable connected for the MSD part? And if you try it via MSD and not FATFilesystem?
posted by Erik - 13 Jun 2013I have both hello worlds working individually yes. trying to combine. I think I am almost there.... been studying the usb composite device example for HID and SD together.
posted by tap tap 14 Jun 2013got it!
posted by tap tap 19 Jun 2013Hey, could you share what you did?
Thanks in advance!
posted by karel.vanroye@... 25 Aug 2013Until he publishes that, this might help you: http://mbed.org/users/Sissors/code/USBFileSystem/
posted by Erik - 26 Aug 2013thanks Eric!
I have now something working see: http://mbed.org/users/karelv/code/SD_USB_FS_HelloWorld/ do I need to call 'connect' from USBMSD in my constructor or not?
Now I created a loop of 1min: 5 sec ==> disconnect 55 sec ==> connect
So I have 55 sec to use my pc to peak the data. When I didn't use connect at all, the SD does not appear as a drive. And when used in the constructor it appears only correct when I comment the write operations in the mbed-main-program.
posted by karel.vanroye@... 26 Aug 2013You can call connect in the constructor, then it immediatly will do the USB drive part. Connect makes it appear as drive, disconnect removes it again. It should also work when you use it in the constructor, but because of some data traffic right after connecting it, it might block your write attempt. In general with the library you should make it so that if a NULL pointer is received when a file is opened it doesn't generate an error, but just waits a bit and tries again.
You will need to keep the disconnect/connect around that function call, or you can set the library to do it automatically for you. But otherwise the data you see on your PC will never gets updated since your PC caches everything. (Actually I think when I release a next version I set that as the default mode). The function you need is:
Maybe the helloworld programs of the library can also give you a starting point. For sure when it works correctly I would like to link your program as an example program.
posted by Erik - 26 Aug 2013So I used now the usbmode 1, and removed the surrounding disconnect/connect. And added again the connect in the constructor.
This works.
Although, it is not very convenient, since my win7 pc always disconnect/connect the drive and at disconnect it also closes the explorer which show the content of that drive. It does the same with the editor that has the file opened.
Do you have any suggestion for that?
posted by karel.vanroye@... 27 Aug 2013Nop :D.
You are correct that that is what happens, got the same on windows 8. The problem is that windows (and probably every other OS) is quite heavy on caching of USB drives. So it reads the data ones, and after that it only writes and assumes its commands have been performed. For example if you have a drive with a bunch of files, and I enable write protection on the library, you can still happily delete the file and windows will tell you it is gone. You can make new files and windows will tell you they are created. Despite nothing actually being done. So the only way to force a refresh is disconnecting/reconnecting. Well not entirely true, I found out if you are writing custom programs you can disable this caching behavior after alot of digging. But in principle it is always on, and you have to reconnect the device. An alternative file browser might have other behavior, but dunno.
So the TL;DR: It is OS behavior that the program can't do anything about. Initially I intended to just use write protection to block the computer from writing, which is why it is still the default, but it doesn't actually work like you want it to work for 99% of the use cases. So reconnecting it is.
posted by Erik - 27 Aug 2013okay... I will your statement on the homepage of the lib. Unless you disallow me of course.
posted by karel.vanroye@... 28 Aug 2013No problem of course. You okay with it if I link it as example program for using the lib with SD card?
posted by Erik - 28 Aug 2013Sure go ahead
En veel plezier ermee!
posted by karel.vanroye@... 31 Aug 2013