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KBloo3
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3 years ago

Cyclone IV E configuration cycle never starts

Hi,

I have trouble in configure my Cyclone IV E FPGA, (The smallest FBGA 256 commercial variant speed grade 8), using the AS, Active Serial programming method.

Here are the implementation details:

  1. Using a EPSC128 SPI configuration device. (+3.0V Vcc) and USB Byte Blaster. The Quartus II programmer detects device ID(0x18) and the SPI Flash gets correctly programmed according to the programmer GUI.
  2. The FPGA MSEL[2..0] pins are put as spec. to [011]. Configuration pins pulled up/down according to spec. except the nSTATUS signal.
  3. The 3.0V Vcc ramp up time is ~ 1.0 ms.

When I’m measure with my oscilloscope I can see that the FPGA configuration cycle never initiates. The FPGA should set the nCS logic low and start the DCLK but that never happens.

One thing I have noticed is that the nSTATUS pin is NOT pulled up. The spec. states it should. From what I understand from the spec. the nSTATUS toggles to indicate that the FPGA POR is released. (Power Supplies ramped up and are stable). Is this nSTATUS signal just a signal that you can monitor or must it indeed be pulled up.

I have another type of circuit board, (a Cyclone IV E and the same SPI Flash), and I moved away the nSTATUS pull up resistor on that board. Still it is no problem to configure the FPGA from the SPI Flash, so I am little bit confused about the need of nSTATUS pull up resistor or not.

Anyone else, of all you good engineers out there, that have had this issue?

Best regards

Kenneth

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