Dear All,

I'm facing a problem with interfacing Serial EEPROM
with TMS320F2806 processor. The device that i'm using
(93C66B microchip serial EEPROM) is connected to the
SPI interface of the processor. I'm able to write data
into the EEPROM. While trying to read the same data
using my DSP, I'm facing the problem. The voltage
level of the Data Out signal from the EEPROM varies
from 0V (logical '0') to 5V (logical '1'). However,
the signal at the DSP end varies from about 0.8V to
3.3V (logical '1'). The reason why the DSP is not able
to read the data is because the Vol(high) (The maximum
value of the low voltage input) for the processor is
only 0.4V but the signal corresponding to logical '0'
input to the processor is 0.8V. 

If any of you have interfaced a serial EEPROM and
faced similar kind of problems, kindly let me know.

Thanks,
Vishal.
       
You can post a message or access and search the archives of this group on DSPRelated.com:
http://www.dsprelated.com/groups/c28x/1.php

_____________________________________

 

hi,
  try to get the data through a max232 chip.
  max232 has processor ports(f2812 or 2806) and computer connection ports (PC side) as u might
know.
  send the data from your eeprom device to transmit pin of max232 on the processor side.
  max232 changes that data to +-12V signal on the computer side.
  connect this +- 12 v signal back to the transmit pin of computer side.
  this data then changes to +-5 or +-3 level digital data on recieve pin of processor side of
max232 chip.
  this can then be used for the recieving.
  i had similar experience and this trick worked.
  bye
  -Chirag

gopalakrishnan vishal anand <a...@yahoo.com> wrote:
          Dear All,

I'm facing a problem with interfacing Serial EEPROM
with TMS320F2806 processor. The device that i'm using
(93C66B microchip serial EEPROM) is connected to the
SPI interface of the processor. I'm able to write data
into the EEPROM. While trying to read the same data
using my DSP, I'm facing the problem. The voltage
level of the Data Out signal from the EEPROM varies
from 0V (logical '0') to 5V (logical '1'). However,
the signal at the DSP end varies from about 0.8V to
3.3V (logical '1'). The reason why the DSP is not able
to read the data is because the Vol(high) (The maximum
value of the low voltage input) for the processor is
only 0.4V but the signal corresponding to logical '0'
input to the processor is 0.8V. 

If any of you have interfaced a serial EEPROM and
faced similar kind of problems, kindly let me know.

Thanks,
Vishal.

You can post a message or access and search the archives of this group on DSPRelated.com:
http://www.dsprelated.com/groups/c28x/1.php

_____________________________________

 

This is the link to the refered document:

http://focus.ti.com/lit/an/spra550/spra550.pdf

hi,
>  try to get the data through a max232 chip.
>  max232 has processor ports(f2812 or 2806) and computer connection ports (PC side) as u
might know.
>  send the data from your eeprom device to transmit pin of max232 on the processor side.
>  max232 changes that data to +-12V signal on the computer side.
>  connect this +- 12 v signal back to the transmit pin of computer side.
>  this data then changes to +-5 or +-3 level digital data on recieve pin of processor side
of max232 chip.
>  this can then be used for the recieving.
>  i had similar experience and this trick worked.
>  bye
>  -Chirag
>
>gopalakrishnan vishal anand    wrote:
>          Dear All,
>
>I'm facing a problem with interfacing Serial EEPROM
>with TMS320F2806 processor. The device that i'm using
>(93C66B microchip serial EEPROM) is connected to the
>SPI interface of the processor. I'm able to write data
>into the EEPROM. While trying to read the same data
>using my DSP, I'm facing the problem. The voltage
>level of the Data Out signal from the EEPROM varies
>from 0V (logical '0') to 5V (logical '1'). However,
>the signal at the DSP end varies from about 0.8V to
>3.3V (logical '1'). The reason why the DSP is not able
>to read the data is because the Vol(high) (The maximum
>value of the low voltage input) for the processor is
>only 0.4V but the signal corresponding to logical '0'
>input to the processor is 0.8V. 
>
>If any of you have interfaced a serial EEPROM and
>faced similar kind of problems, kindly let me know.
>
>Thanks,
>Vishal.
You can post a message or access and search the archives of this group on DSPRelated.com:
http://www.dsprelated.com/groups/c28x/1.php

_____________________________________

 

Hello,

I think the easiest solution is to use a 3.3V Serial EEPROM. There is a application note from
TI that give the guidelines to interface his 3.3V DSPs, have you read it?

hi,
>  try to get the data through a max232 chip.
>  max232 has processor ports(f2812 or 2806) and computer connection ports (PC side) as u
might know.
>  send the data from your eeprom device to transmit pin of max232 on the processor side.
>  max232 changes that data to +-12V signal on the computer side.
>  connect this +- 12 v signal back to the transmit pin of computer side.
>  this data then changes to +-5 or +-3 level digital data on recieve pin of processor side
of max232 chip.
>  this can then be used for the recieving.
>  i had similar experience and this trick worked.
>  bye
>  -Chirag
>
>gopalakrishnan vishal anand    wrote:
>          Dear All,
>
>I'm facing a problem with interfacing Serial EEPROM
>with TMS320F2806 processor. The device that i'm using
>(93C66B microchip serial EEPROM) is connected to the
>SPI interface of the processor. I'm able to write data
>into the EEPROM. While trying to read the same data
>using my DSP, I'm facing the problem. The voltage
>level of the Data Out signal from the EEPROM varies
>from 0V (logical '0') to 5V (logical '1'). However,
>the signal at the DSP end varies from about 0.8V to
>3.3V (logical '1'). The reason why the DSP is not able
>to read the data is because the Vol(high) (The maximum
>value of the low voltage input) for the processor is
>only 0.4V but the signal corresponding to logical '0'
>input to the processor is 0.8V. 
>
>If any of you have interfaced a serial EEPROM and
>faced similar kind of problems, kindly let me know.
>
>Thanks,
>Vishal.
You can post a message or access and search the archives of this group on DSPRelated.com:
http://www.dsprelated.com/groups/c28x/1.php

_____________________________________

 

Hi everybody,

Thanks for all your inputs. As per Ramon's suggestion,
we are going ahed with a 3.3V EEPROM. I was able to
write & read into the EEPROM given in the 2808 eZdsp
board using I2C which is a 3.3V EEPROM. So I've
decided to change the EEPROM on my board also to the
same device.
>From the information we got from TI, it looks likely
that the SPI module in the processor could've been
damaged because +5V could've been inadvertently
applied on the SPI pin. We do not know how to confirm
the same on the processor in our application board.

Thanks once again for all your inputs.

Vishal.

--- r...@msn.com wrote:

> This is the link to the refered document:
> 
> http://focus.ti.com/lit/an/spra550/spra550.pdf
> 
> hi,
> >  try to get the data through a max232 chip.
> >  max232 has processor ports(f2812 or 2806) and
> computer connection ports (PC side) as u might know.
> >  send the data from your eeprom device to transmit
> pin of max232 on the processor side.
> >  max232 changes that data to +-12V signal on the
> computer side.
> >  connect this +- 12 v signal back to the transmit
> pin of computer side.
> >  this data then changes to +-5 or +-3 level
> digital data on recieve pin of processor side of
> max232 chip.
> >  this can then be used for the recieving.
> >  i had similar experience and this trick worked.
> >  bye
> >  -Chirag
> >
> >gopalakrishnan vishal anand    wrote:
> >          Dear All,
> >
> >I'm facing a problem with interfacing Serial EEPROM
> >with TMS320F2806 processor. The device that i'm
> using
> >(93C66B microchip serial EEPROM) is connected to
> the
> >SPI interface of the processor. I'm able to write
> data
> >into the EEPROM. While trying to read the same data
> >using my DSP, I'm facing the problem. The voltage
> >level of the Data Out signal from the EEPROM varies
> >from 0V (logical '0') to 5V (logical '1'). However,
> >the signal at the DSP end varies from about 0.8V to
> >3.3V (logical '1'). The reason why the DSP is not
> able
> >to read the data is because the Vol(high) (The
> maximum
> >value of the low voltage input) for the processor
> is
> >only 0.4V but the signal corresponding to logical
> '0'
> >input to the processor is 0.8V. 
> >
> >If any of you have interfaced a serial EEPROM and
> >faced similar kind of problems, kindly let me know.
> >
> >Thanks,
> >Vishal.
> 

You can post a message or access and search the archives of this group on DSPRelated.com:
http://www.dsprelated.com/groups/c28x/1.php

_____________________________________