Dear Stephan, in message <FCEAKDJJAPHPLJFINDAJOEFEDEAA.Stephan.Linke at epygi.de> you wrote: > > on one of our boards we are using one of the I/O pins in open drain mode. > This leads to some problems in combination with other
Please don't use such long lines, they are hard to read. > drivers that write to the ports data register. Since they can not detect the > current output value of the open drain pin. They only > see the status of the I/O pin no matter who forces the value the CPM or > another device connected to the open drain pin. After > writing back the value read from the I/O data register this value is forced > by CPM which is normaly wrong. This is a feature. It allows you to detect the the state of the pin which can be pretty useful. > Did anyone run into that problem in the past? What was your solution? Any > thing else but NOT using open drain pins? It is _not_ a problem, it is a feature, and a useful one. Solution? What is so difficult about latching your output value in a variable? Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de It is practically impossible to teach good programming style to stu- dents that have had prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration. - Dijkstra ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
