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SSEL as Gpio for SSP/SPI

Question asked by Dimitris Sideris on Aug 31, 2016
Latest reply on Sep 6, 2016 by Dimitris Sideris

Hi there,

 

This post came of as a sequel of this post: https://community.nxp.com/message/827234?commentID=827234&et=watches.email.thread#comment-827234 

 

I ll try to explain what i am trying to do and i need the manual gpio configuration.

 

I am trying to connect through spi an lpcxpresso4367 dev board with an esp8266 dev board. The main goal is to make a pcb with these two chips on board.

 

I am using the SSP1 controller from the side of LPC. The side of esp waits a format of 8 bits command + 8 bits address + 256 bits data.

 

As i figured out the automatic SSEL mechanism of SSP in LPC toggles thes SSEL between high and low between each 8 bit data tha is sent through SSP which is not my case.

 

So i needed a manual manipulation of SSEL and thats why i wanted to handle it as gpio, so that i can set it high and low each time i want to.

 

I connected the LPC to an oscilloscope and found out that clock works nice (clock works each time i m tyring to send sth not permanently).

 

MOSI and SSEL line (configured as gpio) are not behaving correctly.

 

I see MOSI data when SSEL is high and other weird things.

 

I tried to "wrap" send frame commands inside an setlow and sethigh SSEL.

 

I found out that not any time i use sendframe function the frame is sent and now i am tyring to understand the fifo mechanism when it is ready to send a frame and so on.

 

 

 

Now that you know what the big picture of my problem is can y give me any suggestion or help??

 

Thanks a lot in advance!

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