Forum Discussion
Honored ContributorHELP ME about EP2C20Q240C8,PLEASE!
HI ALL
I'm using the cycloneII(EP2C20Q240C8).I want to know what the difference the pin 178 and the others.when i use the pin 178 as LVTTL output,it cannot output a wave (frequency about 25MHz when i use crystal about 50Mhz),but when i use other pin,they can do it.why??? THE wave mentioned above is that i see by the signal-tap. what can i do to solve it?14 Replies
Altera_Forumthank you for your answer,but i have tried in two pcb.the first doubt can be excluded. the second doubt: i check the pin many times.
but i have done another experiment, i use the pin178 to output other slow signal, it can do it.so??????- Altera_Forum
There should be no reason why pin 178 wouldn't function as you want it to.
I suspect you have a either a short between pin 178 and ground, or you are not looking at the right pin (because of a routing swap or so), or because in the logic project the signal is not placed on that pin. - Altera_Forum
no,we just use it as normal IO,as the ADC's control clock,frequency about 25MHz .when we use other IO,it can work well,but when we use then pin178,it cannot output the right wave. i'm so confused!
- Altera_Forum
Pin 178 can be either normal IO or the output of a pll: PLL2_OUTn. Are you driving this pin from logic (e.g as the output of a divider) or directly from the pll? In the latter case it doesn't work: see page 20 of "Pin Information for the Cyclone® II EP2C15A, EP2C20 and EP2C20A Devices.pdf" (http://www.altera.com/literature/dp/cyclone2/ep2c20_ep2c15a_ep2c20a.pdf).
