maikon Posted March 11, 2016 Share Posted March 11, 2016 Hi, I am a new user of FPGAs and I have the CmodS6 kit and I am having in the IO 1.8 V and I need to change it to 3.3V , my ucf shows: NET "PORTA<0>" LOC = "P5" | IOSTANDARD = LVCMOS33 | PULLUP; Vcc is 5V from my usb port and I see at ucf CONFIG VCCAUX = "3.3"; I also had a look at ug381 cdg and ug382. Thanks for your help. Link to comment Share on other sites More sharing options...
JColvin Posted March 11, 2016 Share Posted March 11, 2016 Hi maikon, I'm not sure what the problem is; I know when I look at the master UCF file that Digilent provides from the CmodS6 Resource Center (link here) I don't see the CONFIG VCCAUX setting so maybe that has something to do with it, but in the meantime I have asked some of our applications engineers about this; they'll get back to you here on the forum Thanks, JColvin Link to comment Share on other sites More sharing options...
maikon Posted March 13, 2016 Author Share Posted March 13, 2016 tks for ur support / answer jcolvin, I inserted CONFIG VCCAUX in an attempt to see if I could get 3.3 V in the output. My project is the one from the website and I didn't change it ... Link to comment Share on other sites More sharing options...
maikon Posted March 14, 2016 Author Share Posted March 14, 2016 it might be my setup ! I am using a bread board with leds connected directly to the IOs which might be causing an increase of current which might be dropping the voltage , when I unplugged the LED , the IO register 3.3 V in the output. Link to comment Share on other sites More sharing options...
maikon Posted March 14, 2016 Author Share Posted March 14, 2016 I am measuring the PORTS IO , they are configured as inout and they have IO Buffer connected to them, the exactly same project from the website. When there is no load , the voltage is 3.3 V ! When I connect a LED or a LED plus resistors these INOUT ports have its voltage dropped to 1.8 V. Then I tried to set the pin as an output only and again , open is 3.3 V but when I connect a LED is 2.6 V . ARRRRGGHHH I might be doing some wrong. Link to comment Share on other sites More sharing options...
mwingerson Posted March 14, 2016 Share Posted March 14, 2016 Hello Maikon, 19 minutes ago, maikon said: I am measuring the PORTS IO , they are configured as inout and they have IO Buffer connected to them, the exactly same project from the website. When there is no load , the voltage is 3.3 V ! When I connect a LED or a LED plus resistors these INOUT ports have its voltage dropped to 1.8 V. Then I tried to set the pin as an output only and again , open is 3.3 V but when I connect a LED is 2.6 V . ARRRRGGHHH I might be doing some wrong. How big of an LED are you using? What is the voltage drop and current rating? It sounds like you are just pulling too much current through the pin and this is causing the line voltage to drop. I searched online really quick and found this calculator that might help you. http://ledcalculator.net/ I would suggest using a power FET or BJT to protect the FPGA if you are using something other than a small LED. Best of Luck, Marshall Link to comment Share on other sites More sharing options...
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maikon
Hi,
I am a new user of FPGAs and I have the CmodS6 kit and I am having in the IO 1.8 V
and I need to change it to 3.3V , my ucf shows:
NET "PORTA<0>" LOC = "P5" | IOSTANDARD = LVCMOS33 | PULLUP;
Vcc is 5V from my usb port and I see at ucf CONFIG VCCAUX = "3.3";
I also had a look at ug381 cdg and ug382.
Thanks for your help.
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