programming successful but no function of CPLD - programming successful but no function of CPLD Hi, I am quite new with CPLD design and hope to get help here. For test purposes and learning I made a simple schematic with an external clock of 1 kHz, a 4bit counter (74161) and a BCD to 7 segment decoder (7448). All 4 outputs from counter and 7 outputs from decoder are available on pins of the CPLD. I programmed a MAX300 EPM3064ATC44 on a self made board with a USB Blaster Rev. c. Quartus II programmer reported 100% successful programming and verification. But the counter outputs don't look like binary counting. They are totally confused. I also programmed the same schematic to a MAXII EPM240T100 on a test board from ebay. Again programming was successful but counter outputs are confused. The USB Blaster is a clone from ebay. It contains a STM32FEB but no output driver for level conversion. Both boards, my self made one and the board from ebay, are powered with 3.3 V and also VCC_IO for both chips is 3.3 V. Therefore level conversion is not necessary. The board from ebay was delivered programmed with a blinking example. Therefore the chip should be ok. What could have happened that after successful programming the chips don't work as expected? A picture of the ebay board and USB Blaster ist attached. Replies: Re: programming successful but no function of CPLD I’m glad that your question has been addressed, I now transition this thread to community support. If you have a new question, feel free to open a new thread to get the support from Intel experts. Otherwise, the community users will continue to help you on this thread. Thank you. Replies: Re: programming successful but no function of CPLD Thank you FvM for your tips. It really was a too slow clock slope. After many tests with varying conditions I had a look on the clock slope with high time resolution, see the attachment. The yellow track is the rising edge of original 1 kHz clock and the red one is after an inverter. With the improved slope my circuit works fine. Replies: Re: programming successful but no function of CPLD Hi, May I know from where did you purchase the MAX3000? Is it from Intel authorized distributor? MAX3000 were obsolete back in 2018. Additionally, you can also refer to below page for MAX3000: https://www.intel.com/content/www/us/en/support/programmable/support-resources/devices/max-3000-support.html Regards, Aiman Replies: Re: programming successful but no function of CPLD Hi, which series resistor value? Clock edge may be too slow and cause multiple transitions. As you say it's a self designed board, insufficient power supply bypassing and ground bounce can cause irregular CPLD behaviour. Replies: Re: programming successful but no function of CPLD I use a DSO/state analyzer. It has a 5V 1 kHz clock output. The 5V output is scaled down to 2.8V with a serial resistor and a zener diode. Five channels of the state analyzer show the clock input and the 4 counter outputs which are connected to pins of the CPLD. Replies: Re: programming successful but no function of CPLD Hi, how do you observe the counter output? What's the 1 kHz external clock source, sure it's suited as CPLD clock? Replies: Re: programming successful but no function of CPLD I didn't write code. I used the block editor to design the schematic, see attachment (for EPM240). I also made a simulation which showed correct waveforms. Replies: Re: programming successful but no function of CPLD Hi, I suspect your code in the first place.