CobraMKIII
Newbie level 2
Hello!
In my system I have a Xilinx Spartan 3 FPGA and a CPLD (Xilinx XCR3128XL Coolrunner XPLA3) in my JTAG chain. First device is the FPGA and the second is the CPLD. I want to program the FPGA and bypass the CPLD without using a programming tool like iMPACT. I want to control the programming by another system with a FPGA and my own JTAG routines. I already had success in programming a system with a FPGA and a FLASH in the JTAG chain, there I just ignored to send a BYPASS instruction to the FLASH. Now it seems that I have to bypass the CPLD so it won't be programmed as well.
How do I manage to send a BYPASS instruction to the CPLD without sending a BYPASS instruction to the FPGA as well? Next difficulty is that the length of the instruction register of the FPGA TPA is 6 bit and CPLD TPA is 5 bit.
After bypassing the CPLD, I want to write some instructions into the SHIFT-IR of the FPGA. Because of the JTAG chain, these instructions will also get the CPLD. How can I assert that it stays in the bypassing mode?
I hope someone is familiar on this topic and can help me.
Uli
In my system I have a Xilinx Spartan 3 FPGA and a CPLD (Xilinx XCR3128XL Coolrunner XPLA3) in my JTAG chain. First device is the FPGA and the second is the CPLD. I want to program the FPGA and bypass the CPLD without using a programming tool like iMPACT. I want to control the programming by another system with a FPGA and my own JTAG routines. I already had success in programming a system with a FPGA and a FLASH in the JTAG chain, there I just ignored to send a BYPASS instruction to the FLASH. Now it seems that I have to bypass the CPLD so it won't be programmed as well.
How do I manage to send a BYPASS instruction to the CPLD without sending a BYPASS instruction to the FPGA as well? Next difficulty is that the length of the instruction register of the FPGA TPA is 6 bit and CPLD TPA is 5 bit.
After bypassing the CPLD, I want to write some instructions into the SHIFT-IR of the FPGA. Because of the JTAG chain, these instructions will also get the CPLD. How can I assert that it stays in the bypassing mode?
I hope someone is familiar on this topic and can help me.
Uli