Programmable Devices
CPLDs, FPGAs, SoC FPGAs, Configuration, and Transceivers
20705 Discussions

FPGA IO configed as 1.8V not working

Altera_Forum
Honored Contributor II
1,386 Views

Hi,  

I read from the device handbook and get that the cyclone2 devices support multi-voltage IO standards, such as 3.3/2.5/1.8/1.5 volt.  

I change the IO voltage to 1.5 volt in the device options setting and re-compile, download it to the board and find the output is still 3.3v. Setting them to 2.5 or 1.8v is not working too. 

Am I doing something wrong? 

https://www.alteraforum.com/forum/attachment.php?attachmentid=3716
0 Kudos
4 Replies
Altera_Forum
Honored Contributor II
420 Views

Are the output pins voltage related to those IO/VREFBxNx?

0 Kudos
Altera_Forum
Honored Contributor II
420 Views

The I/O voltage setting has the purpose of informing Quartus about the hardware enviroment. The actual voltage is set by connecting the VCCIO pins to a respective supply. Apparently your board (I guess, a development kit) has all or most VCCIO pins wired to 3.3V.

0 Kudos
Altera_Forum
Honored Contributor II
420 Views

 

--- Quote Start ---  

The I/O voltage setting has the purpose of informing Quartus about the hardware enviroment. The actual voltage is set by connecting the VCCIO pins to a respective supply. Apparently your board (I guess, a development kit) has all or most VCCIO pins wired to 3.3V. 

--- Quote End ---  

 

 

Does the IO voltage setting have purpose other than informing quartus? 

eg, if I want to use max-ii device as level shifter, but one side of the shifter's voltage is variable, you know... 

so I hope the IO voltage setting has only information purpose. then i can chose one setting and change VCCIO without re-compile
0 Kudos
Altera_Forum
Honored Contributor II
420 Views

 

--- Quote Start ---  

so I hope the IO voltage setting has only information purpose. 

--- Quote End ---  

 

This should be true at least for MAX II. With FPGA, the I/O standard also affects the interpretation of the current strength setting.
0 Kudos
Reply