STM32L4 default DFU mode verus Standalone

[uwe2]

Posted on August 05, 2015 at 17:25

We used the DFUSE over USB successfully with several L152 designs. The L152 chips don t have a USB boot loader DFU like described in the AN2606 STM32 microcontroller system memory boot mode. (DFU SE via USB) So we download the slightly modified standalone DFU USB loader and everything works perfect with the L152 chips. We hoped to save this work with the L476 chips, cause there the DFU loader is already preprogrammed from factory.

I thought on the L476 devices the DFU over USB is preprogrammed from factory and all we have to do is to have a 32kHz Xtal and have the BOOT0 pin connected to ground (pattern 7). But this doesn t work like expected. I also found on the Cube, that there is a DFUSE standalone project, which exactly does, what we want. Can anybody explain, why there is this DFUSE standalone project, if ST already have preprogrammed this code directly at factory ? Is the factory preprogrammed code more sensitive to 100% correct USB power settings or should it also work with 3.0 Volts ? Further explanation about the intentions of the 2 different DFU loaders would be highly appreciated. #l476-dfu-factory-preprogrammed-?

[Tesla DeLorean]

Posted on August 10, 2015 at 15:29

The STM32 parts have historically been very fussy about the 32 KHz crystals. They need the 6-7pF ones, not the 9 or 12pF ones. The problems tend to manifest as not starting, or taking an excessive time to start. You can characterize this by starting the LSE and timing how long it takes to come ready, and measure the frequency against the HSE or PLL.

ST uses these on the DISCO boards (when populated)MC-306 32.768K-E3:ROHS

http://www.mouser.com/search/ProductDetail.aspx?qs=tC2qD9afNgo5wsiSIyW37w%3D%3D

http://www.mouser.com/ds/2/137/1705479-465430.pdf

[uwe2]

Posted on August 11, 2015 at 08:18

Finally the ST support could solve the problem.

Depending on the datecode of the ES chips, the 32 kHz operation doesn t work. Unfortunately I had a non working revision.

[israel]

Posted on May 01, 2016 at 21:51

Hi, I use a many time the STM32F100RCT6B and always we have problem with RTC..... some chips just don't start the xtal 32.768Hz.... and there is nothing we can do... (beleave-me I already do everything... hardware and firmware) but just there is not explanation... the problem isn't Hardware and firmware...

I use MC306 xtal and capacitors of 6.8pF... always buy in the mouser....The problem isn't in firmware, the same firmware in the discovery kit always work... in my own PCB some STM32 works and outhers don't work... I have this problem about 9 month and when don't works the LSE (xtal don't start) I have to use LSI, but the problem is that in LSI when the system is turned off the time stop too.... I don't know what to do more... What exactly you wana say when tell... ''Depending on the datecode of the ES chips''I really need help.. pleasseeee

[Tesla DeLorean]

Posted on May 02, 2016 at 00:13

The OP had L4 Engineering Samples ''ES'', I don't think this has any bearing on your F1 parts/issues.

You need to review your circuit and PCB more critically, and perhaps take your failing boards and determine if you have solder shorts, or component issues. You can also change the capacitors and tune your design as built, to come up with something more robust. ST has an app note on the crystal selection and layout. You should discuss and evaluated your design with an ST FAE

[re.wolff9]

Posted on May 02, 2016 at 07:30

•  Using the USB OTG FS port. Probably needs an 8 MHz HSE, but don't see that explicitly stated in the manual(s) right now.

The modern STM32 chips have ''crystalless USB''.  I would guess that the L476 also follows that pattern. If it doesn't it requires a crystal clock. The crystal can be any multiple of 1MHz up to 25MHz. While double checking this, it seems that the L476 does not have the crystalless option. It DOES however allow tuning the MSI using the 32kHz crystal.... What suprises me is that ST admits to the ''system memory'' being flash in the L476 documentation.  

[israel]

Posted on May 02, 2016 at 15:24

Hi Clive, We Sell this board many time.... about 8 month.... we built around 45 boards per month... I already change everything... xtal... capacitors etc... and the problem continue... some chip start RTC and outhers chip just don't start... because this I think the problem is in some chips....

Take a look in my PCB attached (this picture show near of STM32 and Xtal (mc306)... ) a orange circle in part of PCB of RTC. ________________ Attachments : TOP2.png : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0gJ&d=%2Fa%2F0X0000000bcM%2FqfXAosTvzPgqAQ63bsO7JgAxe1D_P98zCTYVkK.LqjE&asPdf=false

[stm32forum]

Posted on May 02, 2016 at 16:31

Start reading

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwi868PPzLvMAhWEBsAKHQ9LCRUQFggdMAA&url=http://www2.st.com/resource/en/application_note/CD00221665.pdf&usg=AFQjCNE2HqvhZex0P-4gWu67LDLzYZ7_RA&cad=rja

. Tell me what EXACT Mc-306 type crystal you have, or mouser partno.

[israel]

Posted on May 02, 2016 at 17:42

Hi, I already read this document before.... I use a MC306 6pF

All itens of my board is ordered in mouser.... the MC306 em Cap used is below

MC 306

http://br.mouser.com/Search/ProductDetail.aspx?R=MC-306_32.7680K-E3:ROHSvirtualkey64320000virtualkey732-MC30632.768K-E3R

CAPACITORs (Tollerance 0.1pF)

http://br.mouser.com/Search/ProductDetail.aspx?R=VJ0805A6R8BXACW1BCvirtualkey61340000virtualkey77-VJ0805A6R8BXACBC

[Tesla DeLorean]

Posted on May 02, 2016 at 18:10

Looks like a two layer board with some scary power routing. Again, going to suggest you walk through your design, and review PCB methods, with your local FAE.

Evaluate the start times for the crystals in your design, and if that is within spec, and that if you have time-outs that those are adequate.

[israel]

Posted on May 02, 2016 at 18:34

Hi, yes is 2 layer... I already see the layout many time... It s me who build and route this board... I can t see something wrong... 

About the timeout.... I don~t have timeout... infinite loop.... I always test in LSE first and wait... if I see don t start I download a other firmware that use LSI....In my test dont have timeout.... and a wait many time... 2 minutes  or more... in my test... really dont start...In my experience I think the route in PCB is ok.... can see nothing wrong... but maybe there is something wrong I dont understand.. I dont know.....