NEEK on board USB blaster

[Altera_Forum]

Hi everyone, 

 Can on board USB blaster on NEEK kit, be used to program / configure external FPGA board via J4 connector mounted on NEEK kit?  Regards.

[Altera_Forum]

you mean by external FPGA that FPGA on another board  

if that i think NO, because J4 connector is an input to starter board not output this means that it is used to program /configure FPGA of starter board  ...................

[Altera_Forum]

Yes, exactly. 

I am asking to configure FPGA on another board. I have studied the schematic of NEEK kit. It seems that USB blaster's all JTAG connection made available at J4. So I think it is possible to configure external FPGA via J4 but not sure.  Regards.

[Altera_Forum]

i am sorry i don't know more but make sure from that because i read in data sheet that J4 is an input :]

[Altera_Forum]

If the external FPGA was on an HSMC card then it's probably doable but other than that no.

[Altera_Forum]

Hi, 

Thanks for reply.  I can not understand why it is not possible to program external FPGA via NEEK kit's on-board USB blaster. What is the exact reason? Let me explain my point on that. If JP1 kept open, the Ep3c25 FPGA on NEEK will be disconnected from J4 JTAG connection. (i.e. TDO of USB blaster is disconnected from Ep3c25's TDI pin) And all the required JTAG pins(@ 2.5 volt level) are accessible at J4 through which external FPGA can be configured.  Kindly enlighten me why this can not be performed in above said way?  Regards.

[Altera_Forum]

I don't have a neek schematic to hand so can't check it to confirm what you say. There certainly needs to be a a way of disconnecting the TMS and TDO pins between the On-Board USB-Blaster and the Cyclone. 

 If you can achieve that then the next issue which may cause you problems is that most of the On-Board blasters are set up so that they disable themselves when a cable is plugged in. One of the ground pins has been re-purposed as a sense pin to make this happen. Disconnecting the sense pin from your cable will avoid this, but take care because if you get this wrong you might fry the On-Board blaster on the NEEK board (or the other board, that one must have the sense pin connected to ground).  The final issue you'll face is that you need to have a good quality short cable between the boards to get the needed signal integrity. 10MHz signals don't go down a standard ribbon cable very far before they are degraded beyond use.