I have been trying to setup an LVDS output where I can control the delay chain. ie: I want to output at 1GHz with manual phase control.
Since I want to run the output at 1GHz, I am using the altlvds_tx to drive the output signal. So far so good. Now I connect it to an altiobuf in differential mode. Still no problem.
Now, I enable the altiobuf option "Enable output buffer dynamic delay chain1". When I try to synthesize, quartus says:
Error (21199): LVDSOUT port of LVDS DPA atom "arriav_serdes_dpa1" must be fed by output pin that does not feed any other logic
Looking in the code quartus generates in the db/ folder, I see that indeed the lvds serdes is fed through a dpa component. I do not need or want dynamic phase alignment. I want to explicitly control the delay chain buffer. I tried directly instantiating arriav_ir_fifo_userdes, but quartus refuses to let me connect it without feeding the signals through an arriav_serdes_dpa.
How can I convince quartus to run the serdes blindly and let me control the delay chain?
PS. I know I can also achieve phase control by shifting a PLL, but that gets me at most 1GHz/8=125ps granularity whereas the delay chain approach offers 50ps.
Since I want to run the output at 1GHz, I am using the altlvds_tx to drive the output signal. So far so good. Now I connect it to an altiobuf in differential mode. Still no problem.
Now, I enable the altiobuf option "Enable output buffer dynamic delay chain1". When I try to synthesize, quartus says:
Error (21199): LVDSOUT port of LVDS DPA atom "arriav_serdes_dpa1" must be fed by output pin that does not feed any other logic
Looking in the code quartus generates in the db/ folder, I see that indeed the lvds serdes is fed through a dpa component. I do not need or want dynamic phase alignment. I want to explicitly control the delay chain buffer. I tried directly instantiating arriav_ir_fifo_userdes, but quartus refuses to let me connect it without feeding the signals through an arriav_serdes_dpa.
How can I convince quartus to run the serdes blindly and let me control the delay chain?
PS. I know I can also achieve phase control by shifting a PLL, but that gets me at most 1GHz/8=125ps granularity whereas the delay chain approach offers 50ps.