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'Implementing I2C questions'
1997\10\22@121652 by ndie Ohtsji [4555]

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Hello all,

I am looking for more info on implementing I2C.  I have read (well
actually only scanned) the information sheets/app notes from
Phillips and Microchip but they don't mention if this bus structure
can be used for non-I2C slave devices such as an LCD display or
switch matrix.

The I2C structure looks very nice (at least to me) but it seems that
it will only work with I2C-ready slave devices.  If I could, I would
really like to implement this structure with non-I2C devices.  Does
anyone know if this is possible and what kind of hardware decoding is
needed.  I am hoping to implement this with the PIC16F84 (the developer's
"fav chip")

Thanks in advance!

Regards from Vancouver, B.C.  CANADA (yep!....It's raining today!)

-Randie "Still very new to PICs" Ohtsji

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/* Glenayre R&D, Vancouver, BC  CANADA   Phone: (604) 293-1611 x4555 */
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1997\10\22@124628 by Thomas Magin

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At 09:11 22.10.1997 -0700, you wrote:

Hi,

>The I2C structure looks very nice (at least to me) but it seems that

it really is !

>it will only work with I2C-ready slave devices.  If I could, I would
>really like to implement this structure with non-I2C devices.  Does
>anyone know if this is possible and what kind of hardware decoding is

Take the PCF8574 from Philips. It's an I2C to 8Bit parallel (and vice versa)
interface chip. So you can connect the LCD to the PCF. With a little bit of
code you can even derive serial clocking, most LCD-Modules need something
like this.

>needed.  I am hoping to implement this with the PIC16F84 (the developer's
>"fav chip")

If you are only driving devices in slave mode I strongly recommend a PIC
with hardware implemented I2C. It's much easier to get results this way
instead of writing lots of I2C-code.

So long

Thomas
=8-)


**********************************************************
* Thomas Magin                  FON:   ++49-761-4543-489 *
* marquette-Hellige GmbH        FAX:                -507 *
* Emergency Systems             email: .....maginKILLspamspam@spam@hellige.de  *
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1997\10\22@172857 by ndie Ohtsji [4555]

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Hi Thomas,

> Take the PCF8574 from Philips. It's an I2C to 8Bit parallel (and vice versa)
> interface chip. So you can connect the LCD to the PCF. With a little bit of
> code you can even derive serial clocking, most LCD-Modules need something
> like this.

Thanks for the lead.  I downloaded the data sheets from Philips and called
the local rep to get me some real data books.

Do you use a second PCF chip for control signals to the LCD? (ie.  r/w,
en, rs lines)

What do you do for a switch matrix using I2C?

Cheers,

-Randie

P.S.  I still don't know if I2C is for me.  I really like it, but I
don't have any devices (including the micro) which use it.  Maybe a
serial EEPROM in the future but I just thinking about future addons
for flexability.



----- Begin Included Message -----

>From maginspamKILLspamHELLIGE.DE Wed Oct 22 09:47:31 1997
X-Sender: magin@mailsrv
Mime-Version: 1.0
Date:         Wed, 22 Oct 1997 18:43:48 +0200
From: Thomas Magin <.....maginKILLspamspam.....HELLIGE.DE>
Subject:      Re: Implementing I2C questions
To: EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU

At 09:11 22.10.1997 -0700, you wrote:

Hi,

>The I2C structure looks very nice (at least to me) but it seems that

it really is !

>it will only work with I2C-ready slave devices.  If I could, I would
>really like to implement this structure with non-I2C devices.  Does
>anyone know if this is possible and what kind of hardware decoding is

Take the PCF8574 from Philips. It's an I2C to 8Bit parallel (and vice versa)
interface chip. So you can connect the LCD to the PCF. With a little bit of
code you can even derive serial clocking, most LCD-Modules need something
like this.

>needed.  I am hoping to implement this with the PIC16F84 (the developer's
>"fav chip")

If you are only driving devices in slave mode I strongly recommend a PIC
with hardware implemented I2C. It's much easier to get results this way
instead of writing lots of I2C-code.

So long

Thomas
=8-)


**********************************************************
* Thomas Magin                  FON:   ++49-761-4543-489 *
* marquette-Hellige GmbH        FAX:                -507 *
* Emergency Systems             email: maginspamspam_OUThellige.de  *
* Munzinger Str. 3                                       *
* D-79111 Freiburg / Germany                             *
**********************************************************


----- End Included Message -----

1997\10\23@024632 by Lars Nielsen

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Try to look at Microchip's application notes AN554
Lars Nielsen
Arhus Kommunehospital
Afd. for Medicinsk Fysik
TLF. 89492487
E-mail @spam@LARSKILLspamspamMEDFYSIK.AAU.DK

1997\10\23@034418 by Thomas Magin

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At 14:27 22.10.1997 -0700, you wrote:

Hi,

>Do you use a second PCF chip for control signals to the LCD? (ie.  r/w,
>en, rs lines)

I don't use any PCF at all. I've only used it to play and examine the I2C
(connecting switches and LEDs). Today the goal is to connect a couple of
PICs to a PowerPC (the embedded version).

>
>What do you do for a switch matrix using I2C?

Maybe there are some "off the shelf" keyboardcontrollers with integrated I2C
available. Another pssibility might be to use a GAL for multiplexind and the
PCF for converting it.

So long

Thomas
=8-)

**********************************************************
* Thomas Magin                  FON:   ++49-761-4543-489 *
* marquette-Hellige GmbH        FAX:                -507 *
* Emergency Systems             email: KILLspammaginKILLspamspamhellige.de  *
* Munzinger Str. 3                                       *
* D-79111 Freiburg / Germany                             *
**********************************************************

1997\10\24@090956 by Mike Smith
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-----Original Message-----
From: Randie Ohtsji [4555] <RemoveMErohtsjiTakeThisOuTspamGLENVAN.GLENAYRE.COM>
To: spamBeGonePICLISTspamBeGonespamMITVMA.MIT.EDU <TakeThisOuTPICLISTEraseMEspamspam_OUTMITVMA.MIT.EDU>
Date: Thursday, 23 October 1997 7:01
Subject: Re: Implementing I2C questions


>Hi Thomas,
>
>> Take the PCF8574 from Philips. It's an I2C to 8Bit parallel (and vice
versa)
>> interface chip. So you can connect the LCD to the PCF. With a little bit
of
>> code you can even derive serial clocking, most LCD-Modules need something
>> like this.
>
>Thanks for the lead.  I downloaded the data sheets from Philips and called
>the local rep to get me some real data books.
>
>Do you use a second PCF chip for control signals to the LCD? (ie.  r/w,
>en, rs lines)


You don't need to.  Assume you are sending bits 0 - 3 to an LCD as data, bit
4 - en, bit 5 - rw, bit 6 strobe?
msb first - write the nibble 0x0d
assume active hi for enable , strobe, write

0110000 - device enabled, write enabled
0111101 - data set, still as above
1111101 - ditto - strobe hi
0111101 - ditto strobe lo
do it again from line 2

>
>What do you do for a switch matrix using I2C?
>

There's an i2c version.

<snip>

>it really is !
>
>>it will only work with I2C-ready slave devices.  If I could, I would
>>really like to implement this structure with non-I2C devices.  Does
>>anyone know if this is possible and what kind of hardware decoding is
>
>Take the PCF8574 from Philips. It's an I2C to 8Bit parallel (and vice
versa)
{Quote hidden}

s/w for doing it aint that hard.

MikeS
<RemoveMEmikesmith_ozspamTakeThisOuTrelaymail.net>

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