Honored Contributor
Honored ContributorThe system is grounded properly,and power supply seems Ok,no avoltage surge.
Today I found that there three pins connect to CPU pin which define as output,but not assign these pin as input or output in Quartus II.And I cut the connection between CPLD and CPU,and measure voltage: 3.3V at CPLD pin,2.0V at CPU pin.Someone says that the pin without assignment will be stuck to GND by Qaurtus II automatically.How Quartus deal with the pin without assignment??stuck to GND or stuck to VCC??Is this the reason cause CPLD damage for over current flowing from CPU to CPLD?
