Ultimate7e tutorial: Processor upgrade

Before I buy is that the right chip?

STM32F103RET6 LQFP-64 STMicroelectronics 32-Bit 72 MHz Anzahl I/O 51

Just to make dubble sure about the Package and Pin numbers.

Another question, there is one capacitor right under the MCU , somebody knows it's value?
While a close inspection I saw fracture at one side of the cap (It wasn't me) but then it's a good occasion to fix it too.

Regards

That is the MCU. - www.ariat.hk/parts/STM32F103RET6 for the 512k version

also on eBay: eBay item number:172431545473

Very inexpensive.

Not sure what the capacitor is as I don't have a 7E opened up at the moment.

ok thx
It's the same

I have to desolder it for messureing and this wont survive the action. I told it has a little crack...

I didn't open up my tx.

Can you check if that capacitor is connected between pin 48 and gnd? If it is, then it is a decoupling capacitor and the STM datasheet calls for a 100nF capacitor there.

silpstream wrote: I didn't open up my tx.

Can you check if that capacitor is connected between pin 48 and gnd? If it is, then it is a decoupling capacitor and the STM datasheet calls for a 100nF capacitor there.

I say" yes" with my little electronic knowledge.
I looked in the datasheet too and found it named as Vdd2 ....I am right?

Used your picture:

One Devo 7e Ultimate more is born Thank you guys!

I desoldered the processor with my cheap 30$ hot air station and soldered it with my iron.

I have been working at an mcu upgrade and have gotten very close but not over the final hump. I have installed the new processor and flashed the bootloader. When I startup it is in program update mode but my computer doesn't recognize the usb device so I am unable to flash deviation to it. I have another U7e that is recognized on the same computer. This is the second mcu I have installed and the behavior is the same with both processors. I have checked the connectivity of the usb pins from the chip pin to the usb cable connector and have no issues there.

I am looking for ideas? I ordered the processors from china what are the chances that the processors have a defect that keeps the usb from working? Is it possible that a component on the board is causing the problem, if so where might I look? I noticed on the mcu pin map in the wiki that there is a usb enable pin that needs to be drawn low, is there a way to manually do this to see if the usb will work?

I may reinstall the origional chip and see if the usb functions but I hate to keep swapping processors. I have also thought of purchasing a chip from digikey or mouser to ensure that I have a first quality processor.

I have checked and rechecked both processors for shorted pins by both visual inspection under magnification and with a multimeter with fine tip probes.

I would appreciate any help you can give.

If you checked all solder joints, then a defect MCU is the reason, because it worked before.
Bought mine from Farnell for 10$ each. I've got them within 3 day's.

@compman2, you might want to check the small cluster of circuitry just next to the usb port. I don't have a picture right now, but it is basically a PNP transistor, 2 resistors and a capacitor. Test that the transistor is ok with a multimeter set to diode testing mode.

That part of the circuit basically enables a pull-up to 3.3v (through the 1.5K resistor) on the D+ pin when the USB enable pin is low. If the transistor is fried, replace it (SS8550) or run small jumper wire from 3.3v to the 1.5K resistor (side away from the D+ pin obviously).

I'll post a pic when I can.

I look forward to pictures. I found the cluster and will get out the multimeter to test. Don't quite understand where to put the jumper if the transister is bad.

Hi all. I have the same situation as compman2 = i've soldered processor, flashed bootloader and then it doesn't recognized in windows. Tomorrow will try to trace usb circuit and will try to test pnp transistor. Thanks, Silpstream!

Here you go. Hope it works.



Have you guys tried uninstalling and reinstalling your windows drivers btw? Also check in windows device manager to see if it shows up at all.

One last thing (a bit silly but I thought I'd mention since it happened to me), you DID remove the jumper across the boot0 pin after flashing right?

I have removed the jumper from boot0 but a good question.

I had tried uninstalling and reinstalling windows usb drivers eariler with no luck. I think they are working right as my other U7e connects correctly.

Tested the transistor and it seems to be good. Negative lead on multimeter to pin 1 and positive on pin 3 or pin 2 give me an identical reading. Reverse the negative and positive and get no reading. Also all other pin combinations give no reading either with either polarity. From what I have read on the internet this should mean the transistor is good.

Is there any harm in putting the jumper on pin 3 to 3.3v source if the transistor is good? Thought I might try this before trying another processor swap. Also is the positive voltage on the TMS,TCK,RST pin header an appropriate place to get the 3.3v?

If this fails I will order another processor from mouser or digikey for my next swap.

Plug a cable in and test connectivity from the side that plugs into the computer to the MCU pins. It's also possible that a solder joint on the usb connector to the main board has cracked from repeated use. This has happened to me on development boards and have cause endless nights of pain.

I believe that the programming header is 3v3. Check with a multimeter to be sure.

No real harm done in adding the jumper, but to be honest, if the transistor is good (your description tells me it is), you shouldn't actually need to do this. You can probe pin 3 with a multimeter to see that you get 3v3 there when the power is turned on and you are in programming mode. If you do, then adding the wire does very little.

Also FYI (since I read back a couple of posts and saw this question posed), the correct thing for the transmitter to do after having the bootloader flashed is to go into programming mode even if the EXT button is not pressed, as it has no firmware to boot into. After firmware is flashed, it should then boot into USB mode if the onboard flash has never been formatted to FAT before, even if the ENT button is not pressed.

I have touched up the pins on the external usb connector but may do that again. At one point I had tested the computer end of the cable to the two usb pins on the mcu and had continuity. I will recheck that since I have swapped in another mcu since those tests.

I will check the pin 3 when in programming mode to see if there is voltage there. I am assuming that I put the ground to the board ground and positive probe to pin 3 carefully. When I pulled the MCU it didn't look like the pin 3 pad had a trace going anywhere. In fact on my other U7e I pulled the pads for 2,3, and 4 and yet have a working device (which I love). I am assuming that when in programming mode the chip itself routes the voltage to pin 3.

I actually meant pin 3 on the transistor as shown in the picture I posted above. You should get 3v3 there. NOT the mcu. Sorry if I wasn't clear.

Wow just unbeliveable what you did here. Big thanks to everbody who is contributing to this amazing project.

I just ordered two STM32F103RET6 for ~3,50€ each. I'm planning to use a cc2500 module and FrSky x4rsb receiver.
Is there any chance of getting advanced telemetry to work?

As afraid as I am to do this process I am willing to give it a shot.

I have two devo7e's and I would like to upgrade the processor on both (one and then the other).

I found where to get the processors but I wanted to verify if this programmer can be used.
ST-Link STM8/STM32 v2 Programmer and Emulator

Many thanks.

Yep. That's the one. Can be found a LOT cheaper than that though. Got mine from eBay for under $4 and it works very well indeed.

eBay item number:252708033038

Thanks RobC62.

The item number you posted doesn't return any results.

Either way, I have gotten used to paying a bit more for items as long as they ship to Hawaii.

Ebay is almost always a crapshoot to get items shipped to Hawaii so I usually just get direct from suppliers.

Many thanks again and I already ordered the programmer and the processors in one go.