Writing application for Stm32F105 @ 25 MHz

Mitchy
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Re: Writing application for Stm32F105 @ 25 MHz

Post by Mitchy »

Just a heads up and also inquiring if anyone else has seen this.
Ordered 5 more Can Bridges with the blue PCB, all with F105s, They look legit, at least the dies are marked from either China or Philippines,
Cube programmer can write to them, clear, etc. and show up as 0x418 device code.
My working codebase doesn’t show any life on these other units.
Took a firmware dump of my working unit, confirmed the new units have identical code via firmware comparison.
Both have the 25 mhz crystal.

Haven’t dug too deep into it yet, most likely a counterfeit chip, but just need to figure out what’s required to get it running effectively.
Mitchy
Posts: 115
Joined: Sun Nov 14, 2021 12:16 pm
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Re: Writing application for Stm32F105 @ 25 MHz

Post by Mitchy »

Just to report back,

Seems the last batch I received have a weak pulldown on the BOOT0 circuit, or else there's some leakage somewhere.
1 out of 5 of the units worked out of the box... That's to say, one worked maybe with some added resistance with a finger or such.

I figured I'd try to ground the BOOT0 pin, and sure enough, all of them fired to life.

Copied over the picture from the reverse engineering site: https://dangerouspayload.com/2020/03/10 ... er-device/
dsc_6293-2-copy.jpg
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