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Posts: 3
Registered: ‎06-11-2018
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MISO signal not visible in SPI interface on BCM53134

Hi folks,

I am trying to establish a SPI connection to a broadcom switch (BCM53134P) as the only slave.

What I have so far is the following: MOSI, SS and Clk is working as expected (see attached pictures):

closerLook0x60FE00.png

Yellow line is hereby the clk signal, blue the negated slave select, the red one the MISO and the green one the MOSI.

I am sending the commands 0x60 (ReadCommand), 0xFE (Address of SPI Status Register) and a dummy byte (0x00). I expected to read the status SPI register, but the level on the MISO channel stays on high.

  • I double checked the connection pins (MOSI: R12, MISO: T12, CLK: P13, SS: P12)
  • I double checked the signal as well (see attached pictures)
  • I checked the configuration in the manual and the SPI interface should be enabled by default
  • Also the switch should have power, since the forwarding mode is active and verified (we are connected two Phy connectors of the switch and looped an ethernet signal)

Do you have any idea, what could I have done wrong?

Is there any chance, the LED08 is pulled down by default?
Can it somehow be possible that the switch is in master state/mode?

Any help / discussion is appreachated!

____ *EDIT* ____

ryanl​ :
Unfortunately I could not reply to your post.
Thanks to your reply anyway:
We double checked the CPU SW implementation. We even did both the normal and the fast read and checked with the a oscilloscope.
- In the application note that I have ("53134-AN103-R.pdf") other application notes are referenced ("53134-AN30x-R.pdf" and "53125-AN20X-R"). Can you tell me where to download / find them?

- Besides the timings on page 166 in the BCM53134P Preliminary Data Sheet ("53134P-DS101-R.pdf"), are there any other restrictions regarding SPI timing? Is there any updated Preliminary Data Sheet?
- Is the modi (CPOL = 1 and CPHA = 1) still up to date?
- Is it a problem for the SPI commumication, if LED_09 is enabled?

Thanks,
Regards,

Tobi

Message was edited by: Clark Gable

____ *EDIT* ____*THE SECOND*_____

ryanl​ :

Hi Ryan, thanks for you help. However, THE PROBLEM STILL EXISTS.
Independent from the first two bytes (command and address), the bits from bit 31 are 0.

I tried to do it with only 0s on the MOSI line and it was the same behaviour.

xo3--00013.jpg

Can you explain the behaviour?
I checked the pads as well by setting the LED08 to zero and enable the Eeprom interface. This works well.

Thanks for your help,
kind regards,

Tobi

Message was edited by: Clark Gable

Broadcom
Posts: 277
Registered: ‎02-15-2016

Re: MISO signal not visible in SPI interface on BCM53134

Hi,

The BCM53134 SPI interface is slave mode which is designed to access by external CPU/host based on the read/write operation flow chart described in datasheet [Programming Interfaces] section.

And the strap pin LED08_CPUEEPROMSEL is default internal pull up to enable SPI interface.

Could you double check your CPU SW has implemented the SPI read/write operation flow chart?

Suggest could you check your local distributor to get our SDK SW to reference and follow our SDK SW SPI driver to implement in your SW?

Thanks,

Ryan

Broadcom
Posts: 277
Registered: ‎02-15-2016

Re: MISO signal not visible in SPI interface on BCM53134

Hi,

Please find the comment below [r] per your questions.

We double checked the CPU SW implementation. We even did both the normal and the fast read and checked with the a oscilloscope.
- In the application note that I have ("53134-AN103-R.pdf") other application notes are referenced ("53134-AN30x-R.pdf" and "53125-AN20X-R"). Can you tell me where to download / find them?

[r]: I am double checking it and will to upload these two application note in this community site asap, will update you once it's done.

- Besides the timings on page 166 in the BCM53134P Preliminary Data Sheet ("53134P-DS101-R.pdf"), are there any other restrictions regarding SPI timing? Is there any updated Preliminary Data Sheet?

[r]: No, the SPI timing in datasheet is updated. One thing please be noted: the SPI and MDC/MDIO interface cannot be connected to the external host simultaneously, when use the SPI interface please make sure to isolate the MDC/MDIO interface
- Is the modi (CPOL = 1 and CPHA = 1) still up to date?

[r]: Yes, Mode 3
- Is it a problem for the SPI commumication, if LED_09 is enabled?

[r]: No, the strap pin LED9_HWFWDGEN is to enable traffic forwarding and it's not related to SPI interface.

Thanks,

Ryan

Broadcom
Posts: 277
Registered: ‎02-15-2016

Re: MISO signal not visible in SPI interface on BCM53134

Hi,

The application note 53134-AN303-R and 53125-AN205-R have been uploaded in this community site BCM53134 folder and BCM53125 folder respectively, please double check it.

Thanks,

Ryan

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