Cannot detect MAX V cpld and Cyclonne 5GX in the same jtag chain

Re: JTAG, yes the TMS and TDI lines are sampled on the rising edge of TCK. TDO will change on the falling edge of TCK.

This is what the JTAG standard calls for so different devices can interoperate in the serial daisy chain.

Your scope shots all look good, I see no obvious waveform issues.

AFAIK DEV_CLRn and DEV_OEn should not affect the JTAG interface.

As to the JTAG test, it may just be using TMS to broadcast to all devices and not care about TDI going into any device. Just guessing.

On boards I design, I always provide resistor stuffing options to bypass around every JTAG device in the chain as a build option.

So we can easily build depopulated boards with missing JTAG devices, or to shorten the JTAG chain to specific devices only. My 2c.

I think at this point you need to isolate to just the MAXV device to get it up on JTAG. It could be a one off bad device or board issue too.