cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
TimNew
Visitor
Visitor
209 Views
Registered: ‎09-11-2020

IIC repeated CPU Monopolization

Xilinx Forum, 

I am using your xiic.c/.h files on a Spartan6 FPGA. Recently I was required to enable the repeated start option. This really impacts the CPU performance. The header file includes the following language. See bolded part. I need the repeated start option to work, but the performance impact is also something my application cannot tolerate either. 

 

* An application can send multiple messages, as a master, to a slave device

* and re-acquire the IIC bus each time a message is sent. The repeated start

* option allows the application to send multiple messages without re-acquiring

* the IIC bus for each message. The transactions involving repeated start

* are also called combined transfers if there is Read and Write in the

* same transaction.

*

* The repeated start feature works with all the API's in XIic driver.

*

* The Repeated Start feature also could cause the application to lock up, or

* monopolize the IIC bus, should repeated start option be enabled and sequences

* of messages never end(periodic data collection).

* Also when repeated start is not disable before the last master message is

* sent or received, will leave the bus captive to the master, but unused.

0 Kudos
2 Replies
drjohnsmith
Teacher
Teacher
195 Views
Registered: ‎07-09-2009

can you explain why you need repeated start ?

 

 

<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>
0 Kudos
venui
Moderator
Moderator
113 Views
Registered: ‎04-09-2019

Hi @TimNew You mean if you use STOP and do START again with out using Repeated start your CPU performance is good?

Regards,

Venu

0 Kudos