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external clamping diode for Cyclone 3

Altera_Forum
Honored Contributor II
‎05-15-2008 02:39 PM
987 Views

Hello, 

 

During implementation I get the following fitter warning: 

Warning: Following 1 pins must use external clamping diodes. 

Info: Pin Nios2Processor:\b_uP_MemInt_I2C:i_Nios2Processor|epcs_controller:the_epcs_controller|tornado_epcs_controller_atom:the_tornado_epcs_controller_atom|the_tornado_spiblock~ALTERA_DATA0 uses I/O standard 2.5 V at N7 

 

My design uses an EPCS flash (powered @ 3V3) and it uses pin N7, which is situated in a 3.3V bank. 

 

This is confusing: 

- The handbook uses a clamping diode to Vccio, in my case that is 3.3V 

- Quartus tells me to add a clamping diode, it doesn't specify to which voltage but I guess that it is the 2V5 

- Is the input buffer for the data0 pin powered by Vccio (3V3) or by Vcca (2V5) ? 

 

Can you clarify this? 

 

thanks and best regards, 

Karel D
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Altera_Forum
Honored Contributor II
‎05-15-2008 04:09 PM
282 Views

When you use a configuration circuit suggested in the handbook, you should simply ignore the said warnings.

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