ADS8344 and BF533

 �
Hi,

I want to interface the A/D(ADS833) from TI with BF533.
This A/D has a serial interface. I have following question

in the SPORT chapter they tell that....... 
 
1)

"The data received on the primary and secondary pins is interleaved in main
memory"  in this sentence does the main memory mean the on chip SDRAM (L1
data memory)? (I am not planning to have any external memory on my board.)
	2)

"For receive, the data bits (DRxPRI and DRxSEC) are synchronous to the
receive clock (RSCLKx). The serial clock is an output if the processor generates
it, or an input if the clock is externally generated. Frame synchronization
signals RFSx  is  used to indicate the start of a serial data word or stream of
serial words."

This A/D ( ADS8344, from TI) has a pin (DCLK) which is a serial/conversion clk.
and the clock speed determines the conversion rate given by Fclk = 24*Fsample 
so I was woundering to which pin of SPORT this should be connected is it the
RSCLKx  or  DRxPRI.

and what has to be done to the other that is not connected?

and  another pin  ( Din) a serial data pin thor' which you have to tell
every time from which of the 8 i/p channels the sample should be converted. I 
don't know as to where this pin has to be connected on BF533??
	3)
In my application this is the only device that is interfaced with the BF533 and
has to selected from the time the board is powered on..so the CS/ ( chip select
, pin that is active low) can that be held low all always? how do I do that?

I hope to hear from you all at the earliest 

Thanks in advance,

Sincerely,

shwetha
	

Hi Shwetha,

My answers are embedded in your mail below.

Regards,
Vikas.

-----Original Message-----
From: adsp@adsp... [mailto:adsp@adsp...]On Behalf Of
shwetha Belame
Sent: Saturday, March 04, 2006 2:40 AM
To: adsp@adsp...
Subject: [adsp] ADS8344 and BF533
	 �
Hi,

I want to interface the A/D(ADS833) from TI with BF533.
This A/D has a serial interface. I have following question

in the SPORT chapter they tell that.......

1)

"The data received on the primary and secondary pins is interleaved in main
memory"  in this sentence does the main memory mean the on chip SDRAM (L1
data memory)? (I am not planning to have any external memory on my board.)

[VIKAS] : "Main memory can be anything that you define through your code.
If
you address as internal memory, then it's internal memory. Hope
Fig6.4(Processor Memory Architecture) in Hardware Reference Manual can help
you a little bit".

2)

"For receive, the data bits (DRxPRI and DRxSEC) are synchronous to the
receive clock (RSCLKx). The serial clock is an output if the processor
generates it, or an input if the clock is externally generated. Frame
synchronization signals RFSx  is  used to indicate the start of a serial
data word or stream of serial words."

This A/D ( ADS8344, from TI) has a pin (DCLK) which is a serial/conversion
clk. and the clock speed determines the conversion rate given by Fclk
=24*Fsample  so I was woundering to which pin of SPORT this should be
connected is it the RSCLKx  or  DRxPRI.

and what has to be done to the other that is not connected?

and  another pin  ( Din) a serial data pin thor' which you have to tell
every time from which of the 8 i/p channels the sample should be converted.
I  don't know as to where this pin has to be connected on BF533??

[VIKAS] : "Basically ADS8344 has SPI interface for reading the data. SPORT
can't be used to generate signals required by ADS8344. You need to connect
to BF533's SPI port. Signals conenctions are as below.

BF533 side		<---->	ADS8344 side

PF1/.../PF7		<---->	CS/		(Any of PF1 to PF7)
SCK			<---->	DCLK
MOSI			<---->	DIN
MISO			<---->	DOUT
PF8/.../PF15	<---->	BUSY		(Any of PF8 to PF15)
PF8/.../PF15	<---->	SHDN/		(Any of PF8 to PF15)

You need to write the code according to your signals connections".
	3)
In my application this is the only device that is interfaced with the BF533
and has to selected from the time the board is powered on..so the CS/ ( chip
select , pin that is active low) can that be held low all always? how do I
do that?

[VIKAS] : "There are two ways to do it.
(i) You can pull-down CS/ of ADS8344 to ground. You need not have connection
to BF533. But you need to make sure that SCLK of SPI port(of BF533) doesn't
toggle unnecessarily. Just check if SCLK toggles upon power-on. Also find
out if the default state of SCLK is '0' upon power-on.
By doing as above, CS/ signal may pick up noise upon power-on that can cause
unintentional data to flow in/out. Also ADS8344 can't be powered down(low
power consumption) if CS/ is always active. The above method is not used
normally. Use the (ii) option below for better results.
(ii) Connect CS/ to any of PF1 to PF7 with a pull-up resistor. Upon
power-on, PF1/../PF7 will be '1'. Write the code appropriately and you
should get correct data irrespective of power-on or fully operational
states. I assume that your entire program code will be residing in BF533's
internal boot ROM".
	I hope to hear from you all at the earliest

Thanks in advance,

Sincerely,

shwetha