Interface BSCAN2 with VexRiscv's JTAG about vexriscv

[Dolu1990]

Hi

Have you seen this doc ? :
https://github.com/SpinalHDL/VexRiscv/tree/master/doc/nativeJtag
Which bscane2 id did you used ?

[ztachip]

Hi I am working on a project that I try to keep it portable between different FPGA as much as possible. Yes, I did try the method described in the doc and it works well. But what I try to do is to instantiate BSCAN2 outside of VexRiscv. This way VexRiscv remains portable between different FPGA since it will just reference standard JTAG signal like TCLK,TDO,TDI,,, Wondering if you can share information how you convert BSCAN2 to JTAG signals. Thanks

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________________________________ From: Dolu1990 ***@***.***> Sent: October 11, 2023 7:23 AM To: SpinalHDL/VexRiscv ***@***.***> Cc: ztachip ***@***.***>; Author ***@***.***> Subject: Re: [SpinalHDL/VexRiscv] Interface BSCAN2 with VexRiscv's JTAG (Issue #370) Hi Have you seen this doc ? : https://github.com/SpinalHDL/VexRiscv/tree/master/doc/nativeJtag Which bscane2 id did you used ? — Reply to this email directly, view it on GitHub<#370 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ACSDUFU2AZLYQ3DBRADGFILX6Z6TXANCNFSM6AAAAAA5ZCYLZA>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[Dolu1990]

Ahh i would say you would have two ways,
Either you expose the jtag instruction interface (bscane like) which can be then bridged to something else. And in the case you want to bridge it from a true 4 pins jtag, you just need to create a little jtag tap which "behave like the bscane2"

Something like :

       val jtag = slave(new Jtag())
        val jtagClockDomain = ClockDomain(jtag.tck) on new Area
          val tap = new JtagTap(jtag, 6)
          val idcodeArea = tap.idcode(B(p.tapId, 32 bits))(5)
          val wrapper = tap.map(debug.jtagInstruction, instructionId = 8)
        }
        

Either you expose the native vex debug interface, which is a small memory bus, and then you provide the bridge from what ever -> to it.