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I am working with a device that has a 100 pin qfp it is labeled: ARM Z STM32F105R8T6

But this part only seems to be available in a 64 pin package.

The R in the number dictates that it is a 64 pin package.

I don't think its mislabeled because I have three boards two of which were ordered a year apart and they're all the same.

Could this be some lame attempt to protect firmware? I can't really think of any other reason on why it would be done on purpose.

What could be going on here?

Newbie Noob
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    Could you name the device and/or post a picture of the chip? It would be boring if you post the pic and then realize that you just didn't count right.. – pipe May 07 '16 at 12:23
  • I have counted loads of times! But yes you're right it is kinda boring without a picture, I'll post one when I'm back in the workshop. – Newbie Noob May 07 '16 at 12:28
  • Hey Terry, old question but I just went through my answers and was wondering if you ever got any definite answers here? Was it some sort of counterfeit product or mislabeling? – pipe Dec 11 '20 at 11:53
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    Hey, no but funnily enough I have just purchased another device and they are still using the same part with the incorrect part number. Back in 2016 I contacted ST and they did get back to me but I never followed it up. I plan to get back in contact with ST so will post an update when they reply. – Newbie Noob Dec 11 '20 at 12:56

2 Answers2

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STM32F105R8

The STM32F105xx and STM32F107xx connectivity line family offers devices in three different package types: from 64 pins to 100 pins.

On the front page of the datasheet:

LQFP100 14 × 14 m

The part is obviously available in a 100 pin package.

But hold on....

Now, this is where it gets interesting. You are indeed right, in that the STM32F105R8T6 should really be a 64-pin part, at least according to the datasheet.

In chapter 7 of the datasheet, table 62, you can find the part numbering scheme. According to that, R equals 64 pins while V equals 100 pins. This is consistent with the information on page 86 and 89, showing the exact marking layout for LQFP64 and LQFP100.

If I were you, I would take a picture of the chip and send to STMicroelectronics. Then update your question with their response, because this is rather interesting.

pipe
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  • Yeah but if you read further and look through their website it looks like that specific part number isn't available in LQFP100 – Newbie Noob May 07 '16 at 12:02
  • @TerryGould Hm, that's interesting. You're right that _R_ stands for 64-pin. – pipe May 07 '16 at 12:06
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Seems from the technical datasheet that this model comes in 2 versions : a 51 I/Os ine LQFP64 package and a 80 I/Os in LQFP100 package. Ordering informations are available on page 93 of the tech datasheet.

EDIT : here is a mouser link for the 100 pin version.

Florent
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  • But as said in my above comment that this specific part number is listed a LQFP64 as dictated by the R. The link shows a different part number, my part clearly displays 105R8T6 as opposed to the LQFP100 105V68T6 shown in the link. – Newbie Noob May 07 '16 at 12:11
  • Oh okay sorry I just understood the actual issue : you have the chip already but the label doesn't suit the pin count. Could be mislabeled... Where did you get the device? Is it "official"? – Florent May 07 '16 at 12:13