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Altera_Forum
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15 years ago

Cyclone III AS Configuration timing question

In the Cyclone III Handbook (Vol 1, Ch 9), it makes it clear that --

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In the AS configuration scheme, the serial configuration device latches input and control signals on the rising edge of DCLK and drives out configuration data on the falling edge. Cyclone III device family drives out control signals on the falling edge of DCLK and latch configuration data on the falling edge of DCLK.

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It subsequently notes that --

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The timing parameters for AS mode are not listed here because the tCF2CD, tCF2ST0, tCFG, tSTATUS, tCF2ST1, and tCD2UM timing parameters are identical to the timing parameters for PS mode listed in Table 9–13 on page 9–39.

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That (PS Configuration Timing Parameters table 9-13 on pg 9-39) only specifies that tdsu (DATA0 setup time) must be at least 5 nsec prior to the DCLK rising edge; and tdh (DATA0 hold time) must be at least 0 nsec after the DCLK rising edge.

My Configuration problem appears to be in the Data0 content that's latched in to the Cyclone III (as delivered during Fast Read) from an EPCS16. These data are latched in on the falling edge of DCLK. I have examined the signal relationship and quality using a scope, but I don't understand the timing specifications from Altera's handbook since for AS Configuration they don't seem to indicate the real setup and hold requirements, relative to DCLK falling transitions.

Does anyone know the C-III AS Configuration read operation setup/hold requirements, to DCLK falling edges? Thanks; Larry.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    In a short, if you didn't introduce special issues in your hardware, I won't expect timing errors with AS configuration. Actually, I never experienced it with any Cyclone I - Cyclone III design.

    Generally, the serial flash communivation is using a SPI mode 0 scheme which should give sufficient timing margin at AS clock speeds.

    You didn't mention the involved Quartus version and AS programming method. Some recent Quartus versions e.g. had bugs related to compressed AS bitstreams.
  • Altera_Forum's avatar
    Altera_Forum
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    Thank you FvM ... the software version is --

    10.0 Build 262 08/18/2010 SP 1 SJ Full Version

    A while back I did change to Uncompressed AS bitstream, since I was slightly suspicious about that. (Unfortunately my alleged frame error remained.) Larry