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The LPC21xx/LPC22xx's SPI. Am I missing something ?

The LPC21xx/LPC22xx's SPI. Am I missing something ?

2004-07-12 by gregdeuerling

Hello,

I have a Maxim thermocouple converter (MAX6675) hooked up to a 
LPC2294's SPI.  The MAX6675 is SPI read only device, i.e., enable 
chip select and it starts shifting out bits on each SPI clock.

Is there no way to make the LPC's SPI receive a byte with out 
sending a byte first ?  I hate to have to bit bang the LPC's I/O's 
to get the SPI functionality I need, but it looks like thats what 
I'm going to have to do.

Am I over looking something ???

Re: [lpc2000] The LPC21xx/LPC22xx's SPI. Am I missing something ?

2004-07-12 by Shannon Holland

On Monday, July 12, 2004, at 11:52 AM, gregdeuerling wrote:

> I have a Maxim thermocouple converter (MAX6675) hooked up to a
> LPC2294's SPI.  The MAX6675 is SPI read only device, i.e., enable
> chip select and it starts shifting out bits on each SPI clock.
>
> Is there no way to make the LPC's SPI receive a byte with out
> sending a byte first ?  I hate to have to bit bang the LPC's I/O's
> to get the SPI functionality I need, but it looks like thats what
> I'm going to have to do.
>
> Am I over looking something ???
>

That's the way SPI works - a byte is received as it sent (as each bit 
is clocked out, a bit is clocked in). You write a byte to the transmit 
register, it sends/receives, then you read the transmit register to get 
the byte back.

Just send a 0 (or whatever) in order to read.

Shannon

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