Dear Matthias, Thanks for this. I have now a complete working I2C connection with my 7seg display and my arduino. Now I working on the tmp75 temperature controller (i2c) When this working I will publish the code for other newbies as I am!
Thanks to all they helped me in the last time, this is a great forum!!! Cheers, Jan kromhout Sacharovlaan 3 3223HM Hellevoetsluis-NL Op 3 jun. 2012 om 19:39 heeft Matthias Trute <mtr...@web.de> het volgende geschreven: > Hi Jan, > > I'm not an expert for TWI, some I've spend some time with EEPROM > modules (dont use the code in the lib directory, its broken). > >> Dear Erich, I have done what you wrote, seems to work.But when I look >> to te code of twi.frt I see some strange thing, or missing >> sommething. When I look into the code never is sending the address in >> twi.start > > That is absolutly ok. The TWI/I2C bus has some unique characteristics, > one is that it can be considered stateful. The master has to send a > start condition (some special combinations of voltages of the affected > lines) and only after successfully aquiring the bus the master can continue. > > When the master has finished its job, it has to send a stop condition > (some special voltage combination again) to release the bus for others > (I2C is multi-master capable). > > Usually the first thing a master has to do after getting the bus is to > select a device to communicate with by sending one byte (In your > case the 0x38). If the devices answers with an ACK (see TWI status), > everything works fine and the next bytes may be transmitted. > Things can get more complicated if the device has to send > data back to the master (EEPROMs)... > > Thus I suspect the arduino code sequence (I do not know the > arduino language) > > Wire.beginTransaction(_7SEG) > ... > Wire.endTransaction(_7SEG) > > should be written as > > 0x38 constant _7SEG > twi.start \ aquire bus > _7SEG twi.tx \ select device > .... > twi.stop \ release bus, maybe reset the device state as well > > You may want to check the Atmel Appnote AVR315 for more information > Its only 11 pages... > > HTH > Matthias > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Amforth-devel mailing list for http://amforth.sf.net/ > Amforth-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/amforth-devel > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Amforth-devel mailing list for http://amforth.sf.net/ Amforth-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/amforth-devel
