LPC2478 SPI SSEL trouble

 LPC2478 SPI SSEL trouble

Hello,

I am reading the measurements of an external ADC connected to a SPI bus. I have noted that even though the LPC2478 is configured as having P0.16 with the role SSEL (SPI), the chip select is not generated upon data transmission (the LPC2478 acts as the bus master, of course). I am forced to manually clear and set P0.16 to correctly address the ADC.
Does this ring a bell? I did ask NXP (just yet), but I was hoping for some unofficial feedback, too...

 RE: LPC2478 SPI SSEL trouble

Michael,

I did come accross something concerning GPIO pins and LPC products. This thread deals with an issue with GPIO and USB (not your problem). It may give you some insight however...

http://www.embeddedrelated.com/groups/lpc2000/show/46087.php

 RE: LPC2478 SPI SSEL trouble

Thanks.

 RE: LPC2478 SPI SSEL trouble

Michael,

Just found this too...

http://www.embeddedrelated.com/groups/lpc2000/show/39662.php

 RE: LPC2478 SPI SSEL trouble

Yes, that's it!
Interestingly, I do not recall seeing any of this in the user manual...

 RE: LPC2478 SPI SSEL trouble

Here is NXP's reply:

"Hello Tamir,

Yes, this is the way it works. SSEL is only used in slave mode. As a master you need to control the slave's select pin in software using a GPIO pin.

Regards,
Paul"