URGENT!! PN5180 SPI interface

[smiwa]

Hi 

I would like to make sure the SPI signal timing between Host and PN5180. What I want to know is how NSS and BUSY should be handled.

Especially, how to control NSS and watch BUSY in read (GET) mode. Please find the attached for my understanding and tell me it is correct or not?

I appreciate your help very urgently...

Best regards,

   S. Miwa

[smiwa]

Hi Weidong san,

Thank you for your kind explanation! 

But I have also read the datasheet you referred and my question is some what detail. Because I must set the time out period to each response action, I would like to confirm the detail sequence and timing. 

Could you also answer me about my revised questions in another session just up 1 hour before?

I appreciate your help!

Best regards,

   S. Miwa

[weidong_sun]

Hello Miwa,

    I discussed the signal with NFC technical team, It's very hard to give an accurate continuous time on "High" state, because at the time PN5180 is handling data, and you know , data size determines the of "High" state, so from datasheet, the "time" was not listed.

   After sending data to PN5180, you will have to wait until the line's state to be LOW. So in software, you had better use "interrupt" operation for BUSY signal.

 Hope above advice can help you!

Best Regards,

weidong

[smiwa]

Hi 

Miwa is writing again to clarify my questions and and correct my depicting in attached document in anothor one.

Please ignore this and relpy to another question!

Thank you very much!

Best regards,

   S. Miwa

[weidong_sun]

Hi,

   NSS signal is Chip select of SPI, The SPI interface of Host should have this signal, such as CS; BUSY signal is used to tell Host if PN5180 is busy, if not, Host can send data, otherwise, host must wait until PN5180 is not busy. Here BUSY means PN5180 is handling data, can't be interrupted.

  You can refer to PN5180 datasheet and will know how to handle NSS and BUSY, see page 15 :

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Both master and slave devices must operate with the same timing. The master device
always places data on the MOSI line a half cycle before the clock edge SCK, in order for
the slave device to latch the data.
The BUSY line is used to indicate if the system is BUSY and cannot receive any data from
a host. Recommendation for the BUSY line handling by the host:
1. Assert NSS to Low
2. Perform Data Exchange
3. Wait until BUSY is high
4. Deassert NSS
5. Wait until BUSY is low

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Regards,

Weidong