[Usb-blaster] Error (209040): Can ' t access JTAG chain

Today, I encountered this problem in downloading the FPGA program to the board of your own design.

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Error (209040): Can ' t access JTAG chainerror (209012): Operation Failedinfo (209061): Ended Programmer operation at Wed Au G to 15:12:29 2016Info (209060): Started Programmer operation at Wed 15:12:31--------------------------------- -------------------------------------------------The point is I have two usb-blaster, one can download a No, this is really very tricks. And then we checked the Altera JTAG spec [1],

Referring to the configuration voltage being limited to vccio voltage, the Vccio is fully 3.3V, so it is suggested that JTAG pin4 voltage is best provided with 3.3V

When using an external usb-blaster, the work voltage of its JTAG interface will be determined by the JTAG Header Pin4,

and I

The pin.4 on the board is designed to provide 2.5V, so the JTAG message will work on voltages up to 2.5V or so.

The use of the Usb-blaster does not work, mainly because the information may be less than 3.3V of VIH voltage, the system can not be judged as high.

And the other one can work right usb-blaster, which is just a good jtag voltage is slightly higher, just over 3.3V of VIH voltage.

If the circuit can be revised, it is recommended that the JTAG pin4 be changed to 3.3v,msel is also set to 101 or 010, the Configuration Voltage standard is 3.3V, so use any of the Usb-blaster Blaster Blaster can be used. If you have any doubts, you can leave the JTAG pin4 with two electrical resistances, connect the 3.3/2.5v voltage, and use a voltage.

It is not clear that the board's PCB traces, so it does not change the JTAG pin4 voltage. So I made a turn and changed the JTAG pin4 to 3.3V voltage,

and change Msel to 010, test UBT and another usb-blaster can be used normally.

[Reference] [1]. Altera Zyclone4, url://https://www.altera.com/content/dam/alterawww/global/en_us/pdfs/literature/hb/ Cyclone-iv/cyclone4-handbook.pdf

[Usb-blaster] Error (209040): Can ' t access JTAG chain