I have Cyclone II board which gets programmed using USB blaster. On that board,
VCCINT = 1.2V
VCCIO = 3.3 V
VCCA = 1.2 V
Now I have made another Cyclone IV board, with above voltages yet USB blaster can not detect JTAG chain.
VCCA needs to be 2.5V for Cyclone IV.
See Table 1-3:
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