Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

ALT_INBUF_DIFF in cycloneII

is possible in cycloneII device use 2 pins INPUT for differential rs422 signal? In quartus2 the differential buffer for cyclone2 is not allowed!
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

You may not connect RS422 directly to an FPGA. Even if a differential buffer would exist. RS422 inputs need to have a common mode range of +/- 10V.

So before interfacing to your FPGA, use a RS422 differential line receiver.

Regards, Ton