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JTAG problems

Hello every one,
We have designed a board which
contains an ALTERA fpga and an EPROM(EPC2LC20).The design is done with
respect to some existing reference schematics.We have populated our
PCB so as to get the power to all the components and then we have
placed the components making up the JTAG circuitary along with the
FPGA and EPROM.
,Altera's Byte blaster is being used
which is working fine. have checked all the circuitary which seems to
be alright but we keep getting the error"Unable to access the JTAG
chain".We have also tried the steps in the ALTERAs trouble shooters.
Do we need to proceed in a different
way while programming the chip/EPROM for the first time.And also what
is the passive serial mode in the Quartus tool for programming. Any
help would be highly appreciated.Thanks in advance.
 
B

Ben Jackson

Jan 1, 1970
0
We have designed a board which
contains an ALTERA fpga and an EPROM(EPC2LC20)

Since that's an obsolete config device you should probably mention
which obsolete FPGA you're configuring with it. Configuration has
evolved quite a bit.
,Altera's Byte blaster is being used
which is working fine. have checked all the circuitary which seems to
be alright but we keep getting the error"Unable to access the JTAG
chain".

I just did the layout for a board with a FLEX 6000 (obsolete but free),
so I happen to know that you can't program them via JTAG (they do support
boundary scan, which is probably not what you want), which brings me to
your final question:
Do we need to proceed in a different
way while programming the chip/EPROM for the first time.And also what
is the passive serial mode in the Quartus tool for programming.

Passive serial is how you configure those old devices. Essentially the
byteblaster drives the same signals as a config device like an EPC1.
The byteblaster is not connected to the JTAG header, instead it is connected
to a header with connections to the serial config lines (DCLK, DATA, OE,
nCS, etc). The pinout is in the byteblaster docs. The same header is
used to program the serial eeprom in-circuit, although there may have
been quirks for the old EPC2-era devices. I didn't include on on my board
at all.
 
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