I am using pull up resistors on both SCL and SDA. Analog is disabled on
RC7. The author of the original code mentions that he wrote the code to be
as universal as possible. I understand the reasoning, it's just
implementing it that's giving me issue. So I re wrote the code and am using
the open drain feature of my micro on SDA and SCL. But now I'm trying to
successfully read from SDA.

On Sat, Oct 19, 2019, 4:13 PM Mike <pic.developer@gmail.com> wrote:

> Do you have pull-up resistors on both SCL and SDA?  Have you configured
> the ANSELC register to disable analog input in RC7?
>
> Using the TRIS register to switch a pin between an input, or an output
> with a logic 0 level set is a common way of simulating an open-drain
> output if this function is not support in hardware. The code you used
> was very likely written for an old 14 bit part (16C/16Fxx etc.) which
> don't have open-drain outputs.
>
> Regards
>
> Mike
>
> On 19/10/2019 22:49, James Burkart wrote:
> > I wrote up a bit-bang I2C routine to communicate with a couple devices,
> an
> > SSD1306 OLED and an MCP23018 port extender. I'm using a PIC18F27K40.
> >
> > I've got the sending data part just fine, but I can't figure out the
> > receiving part, including reading acknowledge bits. I, in large, copied
> the
> > code example from a blog post by Calvin Cherry (
> >
> https://calcium3000.wordpress.com/2016/08/19/i2c-bit-banging-tutorial-par=
t-i/
> > ).
> > To be honest, the way he was switching SDA between an input and output
> was
> > confusing to me and so I just enabled open drain on the port pins in
> > question. And that's why I can write to the I2C bus just fine, but
> reading
> > from it I am stumbling. For my bit read function I change the port pin
> used
> > for SDA to an input and read its value through PORTCbits.RC7 but it's
> > always reading 0.
> >
> > I'd like to use the hardware I2C but I can't get the MCC code to work,
> > either the Foundation Services version, nor the other one that is to be
> > obsoleted soon.
> > --
> > Sincerely,
> >
> > James Burkart
> > *925.667.7175*
> >
>
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