JTAG Chain HPS and FPGA - Excluding HPS or FPGA via Jumpers - Cyclone V SoC

[Altera_Forum]

Hi guys, 

 I want my custom board to be able to connect to both FPGA and HPS via JTAG. To avoid unnecessary cabling I thought of implementing a JTAG chain that includes both HPS and FPGA. However, on the Cyclone V SoC Development Board both devices can be excluded from the chain via jumpers. Do you happen to know the reason for this? Is it important to be able to exclude either HPS or FPGA from the chain? Should I implement this on my board as well if I want to be able to configure FPGA or HPS via JTAG?  Cheers, Adam

[Altera_Forum]

If microcircuit with JTAG-pins is soldered to board, it must be connected to common JTAG-chain without jumpers. Altera don't motivate their swithes ? 

I dont see necessity of "user-conditional" including of device JTAG: always, even used insertable microcircuit/board, constructor may will determine its presence/absence and insert it to common JTAG chain with onboard logic. All modern soft may access to any device in chain and in parallel/sequental to all its set, only various-Blasters need be a little less :)

[Altera_Forum]

The JTAG chain is also routed tio the MICTOR connector. You may want to configure the FPGA via JTAG from the on-board USB blaster, but debug using a tool connected via the MICTOR connector. The jumpers allow you to do this. There may be other scenarios were he jumpers are useful in a development environment. 

 Andrew

[Altera_Forum]

--- Quote Start ---  The JTAG chain is also routed tio the MICTOR connector. You may want to configure the FPGA via JTAG from the on-board USB blaster, but debug using a tool connected via the MICTOR connector. The jumpers allow you to do this. There may be other scenarios were he jumpers are useful in a development environment.  Andrew  --- Quote End ---   Hi Andrew  Thanks for your response. So if HPS and FPGA are fixed in a JTAG chain can I still configure each independently?  Cheers, Adam

[Altera_Forum]

Run Altera Quartus Programmer or Signaltap -- they shows all devices in chain and may work with any independently, with JTAG protocol BYPASS command disable all devices in path to current. Each unnecessary device before sought add 1 tact to any command protocol -- small cost. 

 With MICTOR example is unconvincing, please give situations, when cutting a device from chain allows to get big win or solve problems with its presence.  ...Undoubtedly, jumpers play important role by right using. And best variant -- not "hard" innumerable jumpers and switches, visible on board, then "soft", "virtual" -- through external host program, loadable predefined bit value sets "on/off" (from board customer as Rocketboards, for example) common situations to board nonvolatile memory and is used to program internal small invisible multiplexers. Very comfortable and decrease board sizes, especially if all LEDs will make also "virtual" and see only in PC-based program through JTAG ! :)

[Altera_Forum]

--- Quote Start ---  Run Altera Quartus Programmer or Signaltap -- they shows all devices in chain and may work with any independently, with JTAG protocol BYPASS command disable all devices in path to current. Each unnecessary device before sought add 1 tact to any command protocol -- small cost.  With MICTOR example is unconvincing, please give situations, when cutting a device from chain allows to get big win or solve problems with its presence.  ...Undoubtedly, jumpers play important role by right using. And best variant -- not "hard" innumerable jumpers and switches, visible on board, then "soft", "virtual" -- through external host program, loadable predefined bit value sets "on/off" (from board customer as Rocketboards, for example) common situations to board nonvolatile memory and is used to program internal small invisible multiplexers. Very comfortable and decrease board sizes, especially if all LEDs will make also "virtual" and see only in PC-based program through JTAG ! :)  --- Quote End ---   Thanks WitFed, that was really helpful!  Cheers, Adam