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From: bugzilla-daemon@bugs.ecos.sourceware.org To: unassigned@bugs.ecos.sourceware.org Subject: [Bug 1001639] New: Problems with i2c.cxx Date: Tue, 31 Jul 2012 08:40:00 -0000 [thread overview] Message-ID: <bug-1001639-777@http.bugs.ecos.sourceware.org/> (raw) Please do not reply to this email. Use the web interface provided at: http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001639 Summary: Problems with i2c.cxx Product: eCos Version: CVS Platform: All OS/Version: Other Status: UNCONFIRMED Severity: enhancement Priority: low Component: I2C AssignedTo: unassigned@bugs.ecos.sourceware.org ReportedBy: bernd.edlinger@hotmail.de CC: ecos-bugs@ecos.sourceware.org Class: Advice Request Created an attachment (id=1852) --> (http://bugs.ecos.sourceware.org/attachment.cgi?id=1852) proposed patch to fix this defect There are several problems in the i2c bit-banging base class. 1. The phase position of output data is incorrect. When the SDA bit is written, the SCL rises immediately afterwards. The possbibly different rise times of both signals crate a race condition, because the I2C slave needs to sample the SDA at the rising edge of SCL. 2. The clock stretching is needed for all data transfers, even the stop bit. There have been problems due to missing bit-stretching with SFP Compatible Fiber Optical Transceivers. 3. NAK of the last sent byte is ignored. 4. In the case of a I2C bus multiplexer device, the assertins in cyg_i2c_transaction_xxx are too rigorous. If the I2C Memory is not directly connected, but thru a PCA9547 I2C bus multiplexer, we have to instruct the PCA9547 to switch the I2C Bus, before the I2C Memory can be accessed. Of course the whole process should be a I2C transaction, but the assertions in cyg_i2c_transaction_xxx force all communication only to one slave at a time. -- Configure bugmail: http://bugs.ecos.sourceware.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug.
next reply other threads:[~2012-07-31 8:40 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-07-31 8:40 bugzilla-daemon [this message] 2012-07-31 8:43 ` [Bug 1001639] " bugzilla-daemon 2012-07-31 8:40 [Bug 1001639] New: " bugzilla-daemon
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