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Honored Contributor
Honored ContributorJTAG pin sharing problem
I used the TDO, TDI, TCK as user I/O . The problem is that I can program at the first time with USB blaster but when I program again, it failed. I set the JTAG PIN afile:///C:/Users/Jack/AppDat...
Altera_ForumHonored Contributor
Honored ContributorGeneral thoughts and hints on this subject:
See: https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/hb/max-10/m10_handbook.pdf Have a careful look at the JTAG schematic diagram on page 3-3 • If you intend to switch back and forth between user I/O pins and JTAG pin functions using the JTAGEN pin, all JTAG pins must be assigned as single-ended I/O pins or voltage-referenced I/O pins. Schmitt trigger input is the recommended input buffer. • JTAG pins cannot perform as JTAG pins in user mode if you assign any of the JTAG pin as a differential I/O pin. • You must use the JTAG pins as dedicated pins and not as user I/O pins during JTAG programming. • Do not toggle JTAG pin during the initialization stage. • Put the test access port (TAP) controller in reset state and drive the TDI and TMS pins high and TCK pin low before the initialization. If you use the JTAGEN pin, Altera recommends the following settings: • Once you entered user mode and JTAG pins are regular I/O pins—connect the JTAGEN pin to a weak pull-down (1 kΩ). • Once you entered user mode and JTAG pins are dedicated pins—connect the JTAGEN pin to a weak pull-up (10 kΩ).
