LAUNCHXL-CC1310: The SPI MODE2 CS signal cannot be pulled low

Cherry Zhou

Part Number: LAUNCHXL-CC1310
Other Parts Discussed in Thread: CC1310

Hi team,

Here's an issue from the customer may need your help:

When SPI MODE is set to SPI_POL1_PHA0, the CS signal is pulled high for a period of time after each byte. When CPHA is set to 1, CS can be pulled down directly throughout the process.

With CPHA = 0, is there a way to keep CS low throughout the process?

Could you help check this case? Thanks.

Best Regards,

Cherry

over 3 years ago

0 Sid over 3 years ago

TI__Mastermind 20407 points

Hi Cherry,

Please can you mention if the device is an SPI master?

Regards,

Sid

0 Cherry Zhou over 3 years ago in reply to Sid

TI__Mastermind 22235 points

Hi Sid,

Thanks for your help.

Sid said:
Please can you mention if the device is an SPI master?

Yes, correct.

Thanks and regards,

Cherry

0 Cherry Zhou over 3 years ago in reply to Cherry Zhou

TI__Mastermind 22235 points

And here's a new condition: When reducing the receive data length, CS was kept low throughout the process, and now becomes pull high and then low after each byte is passed.

0 Sid over 3 years ago in reply to Cherry Zhou

TI__Mastermind 20407 points

Hi Cherry,

Thank you for the update, I will investigate this and get back to you with some feedback.

Regards,

Sid

0 Cherry Zhou over 3 years ago in reply to Sid

TI__Mastermind 22235 points

Hi Sid,

Thanks for your support and expect your response.

Thanks and regards,

Cherry

0 Sid over 3 years ago in reply to Cherry Zhou

TI__Mastermind 20407 points

Really sorry about the delays, I will respond to this tomorrow with some feedback.

0 Cherry Zhou over 3 years ago in reply to Sid

TI__Mastermind 22235 points

Sid,

Appreciate your help and expect the feedback! Thanks again.

Regards,

Cherry

0 Arthur R☑️ over 3 years ago in reply to Cherry Zhou

TI__Mastermind 25325 points

Hi,

I am currently trying to reproduce the case you are describing, I will come back to you shortly.

0 Arthur R☑️ over 3 years ago in reply to Cherry Zhou

TI__Mastermind 25325 points

I can indeed observe your issue, but I am afraid it is not possible to assert the pin low in hardware in SPI_POL1_PHA0 mode. At least not on CC1310.

In order to achieve the behavior you want, you will have to control the CS signal through software.

0 YiKai Chen over 3 years ago in reply to Cherry Zhou

Guru 735685 points

Suggest you to use PIN_open/PIN_setOutputValue to set CS pin to workaround this issue.

Sub-1 GHz

Sub-1 GHz forum

LAUNCHXL-CC1310: The SPI MODE2 CS signal cannot be pulled low