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xpercad
Joined: 27 Jun 2004 Posts: 12 Location: MÉXICO
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I2C question |
Posted: Tue Jul 13, 2004 8:24 am |
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I am using PIC18F252 PCWH 3.205 and I2C FAST software generated bus for FRAM memories. I have 2 2.2k pull-up resistors and using pin RA2 for SDA signal and pin RA3 for SCL signal.
From time to time the FRAM memory gets corrupted and I wonder if there is some electrical limitation in using RA2 and RA3 for the I2C bus.
Your help will be most appreciated.
Best Wishes,
Aaron |
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xpercad
Joined: 27 Jun 2004 Posts: 12 Location: MÉXICO
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Question re-phrased |
Posted: Wed Jul 14, 2004 8:09 am |
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What I meant to ask is: the dedicated pins of the PIC18F452 for I2C (RC3 & RC4) have both Schmitt Trigger buffers, and the pins I am using (RA2 & RA3) do not.
Has anybody had any experience using pins (RA2 & RA3) for I2C and had memory corruption problems ???
Regards,
Aaron |
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rnielsen
Joined: 23 Sep 2003 Posts: 852 Location: Utah
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Posted: Wed Jul 14, 2004 9:02 am |
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Most likely, if nobody answers then nobody has experienced this phenomenon. Maybe you could try using the hardware I/O to see if it stabilizes. Then, use a different pair of pins to see if it gets flakey again. If you keep having problems with the non-hardware pins try setting the Slow parameter in your #use declaration. Who knows, it could help.
Good luck
Ronald |
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valemike Guest
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Posted: Wed Jul 14, 2004 1:47 pm |
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I have not had any problems myself.
However, I do know of cases where a noisy environment can corrupt your i2c data. That is why the hardware guy put a few small caps on the SDA/SCL lines. Try lowering your i2c speeds as well. |
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rnielsen
Joined: 23 Sep 2003 Posts: 852 Location: Utah
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Posted: Wed Jul 14, 2004 3:25 pm |
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Caps on I2C bus lines is not a good idea. The I2C protocol states a maximum of 400pf on the bus lines. |
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xpercad
Joined: 27 Jun 2004 Posts: 12 Location: MÉXICO
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Posted: Thu Jul 15, 2004 8:22 am |
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Thanks guys. I will try the SLOW option and I'll report back.... |
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