Hi,
Please advise what should be the cause of bellowing symptom.
All of ICs has JTAG fuse burnt after the first programming.
Some out of thousand ICs didn't perform as expected. So I tried with a simple code toggling a GPIO every 100ms using SW delay (download via BSL).
Good ICs: waveform is as expected.
Bad ICs: actual toggling cycle is every ~700-800ms.
The symptom goes with the bad ICs when I try swapping ICs between two boards.