<cousin_luigi>
If I were to get into this jtag world as a hobby, which adapter would you recommend? Is Aliexpress a valid source for those?
<olerem>
cousin_luigi: depend on what you already have. If you have some SBC like RPi, you can use it as JTAG adapter
<cousin_luigi>
olerem: I have a buspirate v3
<cousin_luigi>
Which, as I understand, is quite slow.
<olerem>
cousin_luigi: is "slow" not good enough for a hobby?
<cousin_luigi>
Probably.
<olerem>
:)
<cousin_luigi>
olerem: It would also require a firmware update, which in turn requires a bootloader update, the tool for which requires an OS downgrade. But I could get to it.
<olerem>
cousin_luigi: any FTDI based adapter woul give you some more MHz
<cousin_luigi>
olerem: I do have a couple, but I bought them as UART adapters, unsure if they would also do jtag.
<cousin_luigi>
Anyway, as I was asking in #electronics, what if the jtag pad is too far for a pogo clamp?
<cousin_luigi>
I thought of using a smd chip holder, since I haven't been in the mood for soldering for a few years.
<olerem>
cousin_luigi: for an FTDI based adapte, you basicly need an FTDI chip and level shifter
<olerem>
interesting, most of tools on seeedstudio are out of stock
<olerem>
are they too popular or not popular enough?
<cousin_luigi>
The latter, I suspect.
<cousin_luigi>
I wonder how much Chinese clones eat into their budgets.
<olerem>
cousin_luigi: heh, most of clone producers eat them self my underming each other
<PaulFertser>
cousin_luigi: what kind of JTAG functionality are you really after?
<PaulFertser>
And do you need SWD?
<PaulFertser>
Hi olerem and cousin_luigi :)
<olerem>
Hi PaulFertser
<PaulFertser>
cousin_luigi: FT232RL (RL!) is only good as UART adapter. For proper JTAG you need something with MPSSE like FT232H.
<cousin_luigi>
PaulFertser: I'm a complete beginner. I wanted to be able to replace the bootloader on a fritz box
<cousin_luigi>
PaulFertser: ok, ft232h, noted
<PaulFertser>
cousin_luigi: also having a good buffer might be essential, bare FTDI breakout is no good as it has very limited voltage range. And with bare breakout you'd need additional series termination resistors on all data lines.
<PaulFertser>
cousin_luigi: for that why not use a raspberrypi or other SBC?
<cousin_luigi>
PaulFertser: Because I don't have any of those.
<cousin_luigi>
Should I buy one?
<PaulFertser>
cousin_luigi: is the procedure already described somewhere for that fritzbox?
<PaulFertser>
cousin_luigi: not for jtagging, no. Have you checked if there's any hackspace within reasonable distance to you?
<cousin_luigi>
PaulFertser: No, but someone mapped the pad
<cousin_luigi>
PaulFertser: not recently
<PaulFertser>
cousin_luigi: take into account just JTAG doesn't allow any operation with the CPU at all.
<PaulFertser>
cousin_luigi: what kind of flash memory (type and package) that bootloader is stored on?
<cousin_luigi>
PaulFertser: Why is that important?
<cousin_luigi>
PaulFertser: I haven't the slightest idea. Perhaps it's documented somewhere.
<cousin_luigi>
Right now I thought of acting proactively.
<PaulFertser>
cousin_luigi: so if you have JTAG you can implement a jig for mass production testing the board on the factory. Doesn't seem anyhow useful for your purposes.
<cousin_luigi>
For I haven't received the device yet.
<cousin_luigi>
PaulFertser: Oh. Why?
<PaulFertser>
cousin_luigi: because JTAG is the standard for boundary scan.
<cousin_luigi>
Should I use a chip clamp and access the flash directly?
<PaulFertser>
cousin_luigi: if possible sure. That's why I asked the previous question.
<PaulFertser>
cousin_luigi: re adapters, probably for stictly hobby purposes a clone jlink is the cheapest reasonable adapter, it has buffers, it supports SWD too, it can capture SWO, it can also do SPI from flashrom.
<cousin_luigi>
Is SPI the way to recover misflashed PC motherboards?
<PaulFertser>
Among FTDI-based adapters AFAICT the cheapest one among the reasonable boards is TUMPA (full, not light!), I also used it for other purposes many times.
<cousin_luigi>
Thanks for the hints.
<PaulFertser>
cousin_luigi: SPI is the name of a communication bus.
<PaulFertser>
cousin_luigi: on PC motherboards you usually see a NOR flash IC with SPI interface used for storing UEFI and other "essential" data (such as ME firmware on intel-based systems).
<borneoa___>
PaulFertser: is review.openocd.org down?
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<PaulFertser>
borneoa___: huh was up just recently, checking
<PaulFertser>
I thought I fixed the issue of it acting up...
<PaulFertser>
cousin_luigi: no clip for that sorry
<PaulFertser>
cousin_luigi: does target SoC probably have an accissible ROM bootloader?
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<cousin_luigi>
PaulFertser: How do you mean?
<PaulFertser>
cousin_luigi: e.g. lantiq targets can be told over UART to load anything to RAM, then you just start u-boot and use that to boot or to flash whatever.
<cousin_luigi>
PaulFertser: Does Intel Seale GRX550 say anything to you?