On Tue, 9 Jul 2002, Harold M Hallikainen wrote:

>I'll consider making another set of functions that check idle. I'd have
>to duplicate pretty much all the functions, but that might be ok. Again,
>THANKS!

The easy way is to copy the relevant library and then edit and insert near
the top of each function something like:

// define a ready-wait procedure
#define I2C_WAIT        if(BI2C_checkidle) { IdleI2C(); }

// for example ...
void SendI2C(uchar8 data)
{
        uchar8  somelocalvar;

        // check for ready
        I2C_WAIT;       // trailing semicolon is optional
        ...

BI2C_checkidle is a flag you define in a global flags register. Beware if
you use this both in ISRs and in main code. The implementation version I
show here is not thread-safe. I hope that C18 inlines the IdleI2C()
function or that it is short. Maybe calling functions with arity 0 is
inexpensive in C18 and then you should keep the code as it is now. My
change will increase code size and/or call depth.

btw imho the skipping of the stop command is a quirk someone came up with
in EEPROM development and ever since all the data sheets repeat it and
cause pitfalls like this. Issuing a I2C stop is so inexpensive code-wise
that I always put it in even in assembly ;-). And to avoid *another*
pitfall (f.ex. if the device does not /ack or is not present on the bus),
I code it on PICs like:

I2C_Stop:
        bcf     Fi2c,Bsda       // or equivalent TRIS manipulation
        bsf     Fi2c,Bscl
        bsf     Fi2c,Bsda

Peter

PS: Once burned forever careful ? What's the proper way to say this ?!

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