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Time stamping | Cypress Semiconductor

Time stamping

Summary: 0 Replies, Latest post by Avagadro on 19 Mar 2013 01:15 AM PDT
Verified Answers: 0
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Avagadro's picture
Cypress Employee
71 posts

 Recently there was a customer request to have a time stamp whenever a message was received on CAN. He was looking for using a RTC to note the time whenever there is a message received and no. of cycles by DMA for time stamp.

DMA is configured to transfer 3 bytes of data from SRAM((RTC_currentTimeDate.Hour, RTC_currentTimeDate.Min, RTC_currentTimeDate.Sec) to SRAM timeStamp array of 3 bytes.

Since this is intraspoke transfer the time taken is =

Arbitration phase time(1) + Fetch Phase(1) + Source engine phase(N + 1) + Destination engine phase(N + 1) + Write back phase(1) = 

1+1+ (3/2 +1) + (3/2+1) +1 = 9 cycles.

So as soon as the message is received the DMA takes 9 cycles to transfer the RTC data to array.

Hope this is helpful:)


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