66AK2H14: Problems with SPI Clock

joe lindula

Part Number: 66AK2H14

Hello, I'm trying to develop a simple, baremetal SPI example program using the 66AKH14 processor. The trouble I am seeing is the data is not correct and the clock has non-uniform pulse widths.

The SPI clock should be 6Mhz and for 16-bit data the total time should be about 2.7us and it but the pulse widths are not the same. I'm expecting the same pulse width, am I correct? Also, the first word I am sending out is 0xA but I don't see that on the MOSI pin.

Any ideas what I may be doing wrong?

Here is my code:

SPI_Example.zip

I'm running the code on DSP Core 0 and using SPI Channel 0.

Thank you very much,

Joe

over 4 years ago

0 joe lindula over 4 years ago

Mastermind 6850 points

I decreased the frequency of the SPI clock to 1Mhz and the clock is looking much better. Now I need to figure out why the data is not looking correct.

Here is what I'm transmitting:

Here is what the SPI signals look:

I'm doing 5 SPI writes and that is what the scope shows. The data on the MOSI does not look like what is in the TXBUF. So I'm looking into that problem.

0 Yordan Kovachev over 4 years ago in reply to joe lindula

TI__Guru**** 161600 points

Hi,

From the memory browser of CCS, could you dump the SPI register values and share them?

Thanks,
Yordan

0 joe lindula over 4 years ago in reply to Yordan Kovachev

Mastermind 6850 points

Hello, thanks for helping me solve this SPI data problem. Here is a screen shot of the SPI registers:

Here is the Memory Save text file starting at the 0x0082BD80.

SPI.dat

Thank you very much,

Joe

0 joe lindula over 4 years ago in reply to joe lindula

Mastermind 6850 points

Hello, I changed the SPI Data width to 8 instead of 16 and I also modified my SPI_SendReceiver() to send the data in the txBuff array. I was sending over a count. Also my Salea Logic analyzer was not setup right. With those changes I got things working.