How PCI express devices talk Article

Post a reply

Confirmation code
Enter the code exactly as it appears. All letters are case insensitive.
:D :) ;) :( :o :shock: :? 8-) :lol: :x :P :oops: :cry: :evil: :twisted: :roll: :!: :?: :idea: :arrow: :| :mrgreen: :geek: :ugeek:
BBCode is ON
[img] is ON
[flash] is OFF
[url] is ON
Smilies are ON
Topic review

Expand view Topic review: How PCI express devices talk Article

How PCI express devices talk Article

Post by Guest » Fri Jun 16, 2017 1:32 pm


Read your article on How PCI express devices talk and have a technical question on the article.
I hope you could address this since your article was very informative.

Since Memory transaction is the basic method of transferring data, how would an user communicate with a SPI device at the endpoint?

Since a SPI READ command are send to the SPI DAC device consisting of a word format for example as:

Device ADDR, Control byte, Configuration byte and Opcode and address register:

The user cannot use the BASIC PCIE Read Request TLP packet because it doesn’t have a DATA Field to store this information.
If the user wants to send multiple form of this SPI Format this is impossible because no Fields are available in a PCIE READ TLP.

Therefore I use a Write Request TLP because I can store this in multiple data FIELD.
After the SPI returns all its register request value,
I package this data in a COMPLETION TLP and wish to send it back to the PCIE Root HOST.
But in PCIE framework, a Write TLP doesn’t support COMPELTION TLP return.

How would this be handle in a PCIE READ transaction to a SPI device or even a SPI EEPROM ?