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Altera_Forum
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10 years ago

Cyclone V SOC - SOCKit - all HSMC pins are high during FPGA config loading

I am trying to figure out why all the HSMC pins are high during boot from the SD Card up until the FPGA configuration is loaded? This takes several seconds. I'm trying to interface the SoCKi...
Altera_Forum's avatar
Altera_Forum
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10 years ago

This is a problem that has caught me out on too many occasions. I should have learnt by now. Some FPGAs (cough Xilinx cough) have an input pin which dictates what the pins do on power up / programming. I'm sure some Altera devices do too though I haven't come across one myself.

Solutions:

  • Redesign your circuitry so all pins are active low.

  • Add pull down resistor to override pull up in chip. If I remember correctly this has to be around 2k2.