first impressions of the Lego smart brick, before I do any actual tearing down: wow, I forgot how good they are at working with plastic.
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unfortunately, i could not access JTAG. i think i ran out of time i have for playing with this board, good luck @ everyone else
shout out to:
https://github.com/nanash1/smart_brick
https://codeberg.org/shelfofsheelfs/SMART-Brick
for doing good work!after reading the datasheet a bit more carefully, i know why i couldn't: the JTAG port is simply not exposed unless the firmware configures the pin mux that way. i'd have to dump the firmware in some other way
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after reading the datasheet a bit more carefully, i know why i couldn't: the JTAG port is simply not exposed unless the firmware configures the pin mux that way. i'd have to dump the firmware in some other way
@whitequark oh how fun, but makes sense for such a pin-constrained device. Is there any other way to access it or is the chip just impossible to reprogram it if it doesnt expose JTAG?
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@whitequark oh how fun, but makes sense for such a pin-constrained device. Is there any other way to access it or is the chip just impossible to reprogram it if it doesnt expose JTAG?
@cinebox it has a bootloader which I assume is how it's programmed by LEGO; I think I know how to trigger that but I just wanted to connect JTAG because it was more challenging to solder these tiny wires and I'm bad at doing it
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after reading the datasheet a bit more carefully, i know why i couldn't: the JTAG port is simply not exposed unless the firmware configures the pin mux that way. i'd have to dump the firmware in some other way
@whitequark could it have booted in cJTAG mode?
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@whitequark could it have booted in cJTAG mode?
@ldcd the datasheet explicitly says the JTAG pins are GPIO'd
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here's a video that shows in more detail the moldwork in the transparent plastic part
@whitequark are the pips on top buttons too?
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@whitequark are the pips on top buttons too?
@lenary no, just normal lego brick shape
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not my best work but it should do the trick
feat. comically big q-tip
@whitequark I know this seems like an ordinary jump to you but if I managed to get one as clean as this, I'd feel like a goddamn hero
I ruined a beautiful rf01(one of those xbox 360 donor rf recievers wired through usb) with my soldering
Then it died but I think that was because I wasn't supplying the right power the right way(iirc it wanted a stable 3.3v and I just gave it a nodemcu 3v3) which was a common problem on these boards
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@whitequark I know this seems like an ordinary jump to you but if I managed to get one as clean as this, I'd feel like a goddamn hero
I ruined a beautiful rf01(one of those xbox 360 donor rf recievers wired through usb) with my soldering
Then it died but I think that was because I wasn't supplying the right power the right way(iirc it wanted a stable 3.3v and I just gave it a nodemcu 3v3) which was a common problem on these boards
@sounddrill if you're in the area I can teach you how to do it as cleanly as this. nothing special about it
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finally done. no shorts and (as far as i can tell under mag) no opens
@whitequark This is wonderful
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@whitequark but the most important question remains unanswered: Can you make it play actual star wars sounds instead of the unintelligible gibberish now?
@triplef that would have to involve the totally undocumented ASIC
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@triplef that would have to involve the totally undocumented ASIC
@triplef honestly the easiest way would be to join LEGO and get all the docs. I probably could do this if I wanted
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@sounddrill if you're in the area I can teach you how to do it as cleanly as this. nothing special about it
@whitequark I'm way out in South India but hey, thanks!
I first learned basics of PCB design years ago over a discord server so I'll be sure to ask if I need to pick something up
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@ldcd the datasheet explicitly says the JTAG pins are GPIO'd
@whitequark yup i only mention because TMSC (GPIO11) and TCKC (GPIO10) both go straight to vias (and then maybe to the array of testpoints on the back?); Wheras TDO (GPIO9) seems to go to the flash and TDI (GPIO8) seems to go ??.
So I was thinking there's a chance they might be explicitly configuring it as cJTAG and using it for a boundary scan test after manufacture.
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@whitequark yup i only mention because TMSC (GPIO11) and TCKC (GPIO10) both go straight to vias (and then maybe to the array of testpoints on the back?); Wheras TDO (GPIO9) seems to go to the flash and TDI (GPIO8) seems to go ??.
So I was thinking there's a chance they might be explicitly configuring it as cJTAG and using it for a boundary scan test after manufacture.
@whitequark if the REd schematic is to believed TCKC goes only to a testpoint
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@whitequark if the REd schematic is to believed TCKC goes only to a testpoint
@ldcd hm it's possible but i haven't implemented cJTAG yet so can't easily test
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@ldcd hm it's possible but i haven't implemented cJTAG yet so can't easily test
@whitequark yeah it's a PITA I was trying to bring up a CC1354 and just could not get it to respond
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@whitequark yeah it's a PITA I was trying to bring up a CC1354 and just could not get it to respond
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@whitequark in theory you can use openocd to wake it up and switch it to 4 wire mode but thats also not very fun;
in the TI parts the GPIO mux is subordinate to the JTAG TAP so if you wake up 4 wire mode it takes over the other two pins no matter what the GPIO mux is set to afaict
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after reading the datasheet a bit more carefully, i know why i couldn't: the JTAG port is simply not exposed unless the firmware configures the pin mux that way. i'd have to dump the firmware in some other way
@whitequark Just in case this were really the end... would you give away your PCB in the state it is right now? And maybe some advice how to dump it? I guess you mean the configuration mode thingie?
