Reply by Kenneth Ciszewski June 19, 20062006-06-19
In looking at the data sheet, if this part is SPI compatible, then I don't see any other way to interface to it than to connect MOSI and MISO together. You may have to tristate MISO when receiveing data. When transmitting data to this part, your SPI receive register in the DSP will see the data you are transmitting. You may or may not have to clear this register before receiving data.

Please note that the data sheet shows the use of the /CS pin as part of the overall interface.

Hardeep wrote:
Hi,

I have a couple of questions related to interfacing the SPI module
(DSP56858) to a temperature sensor (TMP122:
http://focus.ti.com/lit/ds/symlink/tmp122.pdf ). The TMP122 has a
single I/O line whereas the DSP uses two separate lines, MOSI and
MISO.

Please tell me if this is feasible to use with the DSP: Tying MOSI
and MISO together and tri-stating MOSI each time I wanted to receive
data.

-Firstly, is connecting MOSI and MISO together allowable?
-By changing the MOSI pin to a GPIO and its direction to an input,
make it go to tri-state?
-Is changing the pin mode (ie: making MOSI a GPIO/peripheral) while
SPI is enabled, allowed?
-If DSP is the master, is initiation of the clock done after a word
is put into the transmit register? Can initiation of the clock be
done if DSP was reading from the receive register?
Thank you.

Hardeep
Reply by Hardeep June 15, 20062006-06-15
Hi,

I have a couple of questions related to interfacing the SPI module
(DSP56858) to a temperature sensor (TMP122:
http://focus.ti.com/lit/ds/symlink/tmp122.pdf ). The TMP122 has a
single I/O line whereas the DSP uses two separate lines, MOSI and
MISO.

Please tell me if this is feasible to use with the DSP: Tying MOSI
and MISO together and tri-stating MOSI each time I wanted to receive
data.

-Firstly, is connecting MOSI and MISO together allowable?
-By changing the MOSI pin to a GPIO and its direction to an input,
make it go to tri-state?
-Is changing the pin mode (ie: making MOSI a GPIO/peripheral) while
SPI is enabled, allowed?
-If DSP is the master, is initiation of the clock done after a word
is put into the transmit register? Can initiation of the clock be
done if DSP was reading from the receive register?

Thank you.

Hardeep