Hi Colin, Thanks for clearing up my misunderstanding of how owcapi functions. I'd initially rejected owserver because it provided network access and network access is inappropriate in our embedded system. The data in the DS2505 memory device contained in a connected attachment is configuration information for the attachment which the system uses to correctly operate the attachment. The simple solution would appear to be using owfs and basic file I/O to read the DS2505 memory. Thanks for your help!
Regards, Larry -----Original Message----- From: Colin Law [mailto:clan...@gmail.com] Sent: Thursday, September 11, 2014 2:14 PM To: OWFS (One-wire file system) discussion and help Subject: Re: [Owfs-developers] code not able to access owfs Hi Larry I believe the point is that owcapi does not access the owfs file system, it accesses the 1-wire bus directly. If you are running owfs at the same time then that will also be trying to access the 1-wire bus, and so owcapi fails (as the bus is already in use). If you want to use owfs then from your application access the file system directly in the same way you would access a file from your application. I also think, however, that you should consider not using owfs but use owserver. It is easy to access values from code via owserver (that is what it is designed for). It also has the great advantage that it can be accessed from a different machine in case that ever becomes desirable. Colin On 11 September 2014 18:19, Howell, Larry (Contractor) <larry.how...@stryker.com> wrote: > Hi Stefano, > > > > Thanks for your reply. > > > > I don’t understand why owserver would be necessary, since the > application code has a single local client process. The DS2482-800 > has 8 channels, which appear in the filesystem as bus.0 through bus.7, > but bus.5 – bus.7 are not used. A single DS2505 2KiB memory may be > connected to bus.0 through bus.4. Each bus is read in a loop to > determine if an attachment is connected, as indicated by the presence > of the DS2505 0B family code in the filesystem. We’re using owcapi > lread() to read the filesystem at > mnt/1wire/uncached/bus.n/0B.xxxxxxxxxxxx/memory as we sequence through the 5 > buses that may have an attachment connected. > > > > As stated in my previous message, the filesystem can be read from the > bash shell by the same non-root user that owns the application code, > but filesystem access from the application gives a “permission denied” error. > > > > This is my first use of owfs and owcapi, so I may be misunderstanding > its correct usage. > > > > Thanks, > > > > Larry Howell > > > > From: Stefano Miccoli [mailto:mo...@icloud.com] > Sent: Wednesday, September 10, 2014 7:28 PM > To: OWFS (One-wire file system) discussion and help > Subject: Re: [Owfs-developers] code not able to access owfs > > > > Are both owfs and your application trying to access directly /dev/i2c-2:0 ? > Has the owcapi application the privileges for reading /dev/i2c? > > > > If you run owfs, application programs should access sensors via the > filesystem (not owcapi). > > Maybe a better approach is to run owserver (instead of owfs) to access > the bus and have application programs use ownet (see examples in > module/ownet/c/src/example). > > > > From 'man owserver' > > > > owserver (1) is the backend component of the OWFS > 1-wire bus control > > system. owserver (1) arbitrates access to the bus from > multiple client > processes. The physical bus is usually connected to a > serial or USB > port, and other processes connect to owserver (1) over network > sockets > (tcp port). Communication can be local or over a network. > Secure > tun- > neling can be implemented using standard techniques. > > Frontend clients include a filesystem representation: owfs (1) > , and a > webserver: owhttpd (1). Direct language bindings are also > available, > e.g: owperl (3). Several instances of each client can be initiated. > > Each client can also connect directly to the physical bus, > skipping > owserver (1) but only one client can connect to the > physical bus > safely. > > > > bye, Stefano > > > > On 10 Sep 2014, at 17:43, Howell, Larry (Contractor) > <larry.how...@stryker.com> wrote: > > > > Our project is developing an embedded system running Linux 2.6.35 on > an i.MX53. Fuse is built in to the kernel. The system utilizes > plugin devices that store configuration data on internal DS2505s. > We’re using owfs-2.8p15 and writing application code based on the > owcapi. The system uses a > DS2482-800 bus master and the initialization parameters are > ‘i2c=/dev/i2c-2:0 –m mnt/1wire --allow_other’. The filesystem mounts > with expected permissions, and non-root users can access the > filesystem with no problem from the bash shell. However, the > application code fails all attempts at filesystem access with a > ‘permission denied’ error. Searching the owfs man pages hasn’t > provided any clues about this problem. Any pointers or suggestions would be > greatly appreciated. > > > > Thanks for your help! > > > > Larry Howell > > > > ---------------------------------------------------------------------- > -------- > Want excitement? > Manually upgrade your production database. > When you want reliability, choose Perforce Perforce version control. > Predictably reliable. > http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg. > clktrk_______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers > > > > > ---------------------------------------------------------------------- > -------- > Want excitement? > Manually upgrade your production database. > When you want reliability, choose Perforce Perforce version control. > Predictably reliable. > http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg. > clktrk _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers > ------------------------------------------------------------------------------ Want excitement? Manually upgrade your production database. When you want reliability, choose Perforce Perforce version control. Predictably reliable. http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg.clktrk _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers ------------------------------------------------------------------------------ Want excitement? Manually upgrade your production database. When you want reliability, choose Perforce Perforce version control. Predictably reliable. http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg.clktrk _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
