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Altera_Forum's avatar
Altera_Forum
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12 years ago

cyc4 JTAG AS config questions

I am using the EP4CGX30BF14 device with an EPCS16SI8N flash and a JTAG connector. I'm using Fig 8-29 from the handbook for my setup, so SFL and only one JTAG connector. I'm a bit confused on a couple of fronts.

1) My VCCIO on bank 8, same bank as flash and JTAG, is 2.5V. From what I've read so far, this seems fine to do. Anything here I should watch out for? Any gotchyas?

2) My bank 3 VCCIO is 3.3V. This is where my MSEL, CONF_DONE, nSTATUS, CRC_ERROR, NCEO, and INIT_DONE pins are present. My bank 8 VCCIO is at 2.5V and this bank also contains configuration pins, JTAG, and flash device. I'm supposed to connect the MSEL pins for AS but there are two different AS options, 3.3V and 3.0V/2.5V, depending on the VCCIO of the bank in which the configuration pins reside. But what is defined as configuration pins? Which bank should I look at as my configuration bank? The note under table 8-3 states "(1) Configuration voltage standard applied to the VCCIO supply of the bank in which the configuration pins reside." I'm just not clear which bank the statement is referring to.

Thank you for your time.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    The configuration pins refers to the bank in which your configuration device lies - in your case bank 8. So, you need to set your MSEL pins for 2.5V AS mode (MSEL[2:0] = 011).

    As for the other signals you refer to: CONF_DONE & nSTATUS are open drain outputs that report the configuration status. I recommend pulling these up to the voltage of the bank in which they reside - bank 3, 3.3V in your case - although they can be pulled up to a lower voltage if required.

    The balance of those pins (except MSEL - see below) are all outputs which reside on dual purpose pins that you can chose what to do with, thus have no restrictions or impact on your MSEL strapping.

    Finally, MSEL. This may well reside in bank 3 (powered to 3.3V in your case), but these should be tied to GND or VCCA (2.5V), as specified in the configuration guide. See page 8-8.

    Regards,

    Alex
  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    Thank you Alex for taking the time to respond. Your post solved it for me. I normally select the same voltage for both banks just to avoid this issue. I couldn't avoid it on this project and the handbook confused me.

    v/r,

    Shannon