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evan
Joined: 02 Apr 2012
Posts: 22
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| reusing #use (spi and i2c) - help! |
 Posted: Fri Aug 29, 2014 11:22 am |
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Hi all,
I've got a tricky problem. My hardware is constrained by lack of pins, so I combined i2c and spi peripheral devices, sharing clock and data lines (using the software driver libraries).
Electrically it works fine and I am able to configure the i2c devices first, then the #use SPI call, then the SPI device is accessed. All OK.
However, now I need my program to access one of the i2c devices occasionally, after the #spi call.
But apparently the #use i2c call can't be done more than once. I get
| Code: | | Option invalid Bad Option: 116 |
How can I get the libraries to share? I realise this is a little non-standard but I know the library code is there and it does work perfectly.
Is the only way to code my own SPI routine? That would be a pain!
Thanks
Evan |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19448
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| Posted: Fri Aug 29, 2014 1:14 pm |
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Key to understand, is that #use, is a preprocessor directive, not code.
Setup the two #use statements, with different stream names, and use these with the i2c/spi functions.
However I'm very surprised you can mix the buses. Given that I2C, is an 'open collector' bus, while SPI requires hardware pull up/down.
Tell the two statements to both force software mode, and then manually float/drive the pins involved, before switching. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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