Debugging a SuperH4 target (Anritsu MS2721B) #290
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I emailed a few of the J-core devs yesterday and here's a nice piece of info about those special SH4 JTAG debuggers:
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Happy to sponsor https://apnet.co.jp/product/superh/ap-sh4-1a.html dev board to elucidate H-UDI and have as much as possible supported on Glasgow as discussed over IRC. Feel free to reach out to brainstorm at nopcode dot org for logistics, no rush ;) |
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I had some experience debugging STi7105 with ST40 Micro Toolset, I think parts of this toolchain are available somewhere on the internet (you know whom to ask, wink-wink) The adapter is just a regular FT2232 mini module with changed device name and VID:PID pair.... |
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Ive been reasearching on this the last couple days. Im interested in finding a debugger for Casio Calculators with SuperH SH4 CPU. Appearently there has been a debugger for the Sega Dreamcast 25 years ago. So there is a chance that i can get it to work on a calculator https://www.sega-dc.de/dreamcast/Dreamcast_Debug_Handler There is a japanese website that sold their own Flashers and debuggers. Thir device XrossFinder has a driver that has a few FTDI entries. Like it says FTDIBUS.INF. It could be an FTDI with a modified firmware. Or maybe the FTDI is used to communicate with the debugger. Idk I also extracted the files from the official E10A Debugger update and High Performance Embedded Workshop software update. There are drivers and a program e10aset.exe. That program is appearently used to switch modes and set up the debugger for different CPUs. But its loading a 109 kb E1adp.mot file (which i dont know yet what arch it is, its not SH4 assembly). I hope it has something to do with the device firmware. If someone is interested i can send files. |
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Just a random scattering of notes from trying to figure this out myself for a SH7724. STMicro also licenced the SH4 arch under the name st40 - which also uses H-UDI although in some docs they've dropped the "H". Someone has made a fork of urjtag (https://github.com/jekkos/urjtag-st7xxx) which has partial support for the ST40. I tried this with dirtyjtag (did have to backport dirtyjtag support into the st7xxx fork) along with changing the dirtyjtag setup to push pull (though I don't know if this is right) for the CS_RESET pin - which is being used for the ASEBRK IO. This didn't really work for me (not really surprised). The st7xxx fork requires a I have no idea if the stlinux Apparently the SH7724 is in the SH7780 series, and there is a BSDL for the SH7780 however I don't think this lines up very well. It's suspect BSR is still possible on the SH7724 even without using H-UDI - but not sure- I see stuff changing when using the For reference, my desired outcome is either jmp'ing the cpu to a memory location or reading/writing flash, as a fuckup with u-boot has resulted in every command in u-boot returning "Unknown command - try 'help'" |
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While attempting repair of an Anritsu MS2721B 6GHz "portable" spectrum analyzer, I mapped out the JTAG pinout of its main SH4 (SH7750R) MCU on the board.
For context, the unit was working before but stopped booting up, so now I'm trying to figure out where exactly is the device halting within the (early) boot sequence.
Then I went for Glasgow to confirm the JTAG pinout and indeed, those pins are well identified:
And they also spit some TAP info:
And even attempted to establish some JTAG bitbanged session for OpenOCD, similar to my previous attempts with an ESP32S2:
But then after scanning OpenOCD for suitable targets, I couldn't find any SuperH4 related ones. So I went back to the datasheet linked above and sections 20 and 21 describe what seems to be a customization (extension?) of JTAG called "H-UDI" (and its debugging support called "UBC").
Also there seem to be some 12-y.o dead end threads on renesasrulz.com regarding BSDL availability for those targets.
Is there somebody experienced with this target within this community? Is there any prior art of OSS tooling for SH4 that somebody can point me to?
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