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OA47

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Joined: 11/04/2012
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Posted: 03:56am 23 Feb 2022

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I have an F4 board new out of the bag that is not co-operating and need a little help to diagnose the issue. The unit will not detect with the CUBE software so I cannot load MMBasic onto it. Firstly the unit powers up with the USB plugged in, the two LEDs blink as they should and I can read the contents of the SD card.

I have tested the 1117 reg and all voltages seem OK.
I have continuity tested the USB pins to PA11 & PA12 and the BTO & BT1 pins to the CPU.

I did reflow the CPU under the microscope and no change.

I am assuming that as the LEDs (D2 and D3) are blinking that there is a sketch that is running on the CPU but can be corrected if I am assuming wrongly.

The RESET button does cause the USB and CPU to reset.

Any hints as to where I would look next would be much appreciated.

OA47

disco4now

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Joined: 18/12/2014
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Posts: 1003

Posted: 04:51am 23 Feb 2022

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Just to confirm:
You have BT1 connected to 3.3v when power is applied to get it into bootloader mode.

Do you see the STM32 BOOTLOADER entry under Universal Serial Bus Devices in Device Manager.
Is it windows 10 or something else ? WIN7 needs a driver loaded.

If BOOTLOADER thing is there you should select USB in STM32CubeProgrammer and then hit the refresh icon to find the port.

Normally BT0 to GND is not required but I remember one case where it was also required.

I think it is also possible to program via the serial port if you can't get usb to go. (You would need a USB to serial adapter).

Maybe try a different USB (known good) cable to rule that out.

Gerry

Latest F4 Latest H7 FotS

OA47

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Posted: 05:15am 23 Feb 2022

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Thanks for the reply Gerry. I forgot to mention that I had three other units in this batch that all loaded up MMBasic fine so my PC side of things is working correctly.

OA47

PS I actually linked the bad unit with a good unit over the 5V pins and did some spot voltage checks around the boards to see if I could locate a major discrepancy but unfortunately it seems that when MMBasic is loaded you do get a lot of voltage changes around the chip.

Edited 2022-02-23 15:21 by OA47

phil99

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Joined: 11/02/2018
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Posted: 05:30am 23 Feb 2022

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Had a similar issue that turned out to be a dodgy jumper, it often went open.
The F4 I have requires BT0 to be held low for normal operation and BT! high for programming, and does odd things if BT0 is open.
Edited 2022-02-23 15:34 by phil99

OA47

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Posted: 05:40am 23 Feb 2022

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Thanks Phil, The jumpers were OK as I was using the same jumpers on each board as the supplier of these boards was a bit stingy and didn't supply them. I did measure the voltages on BT0 and BT1 and they were correct. The CPU is recognizing the jumpers as it stops the LEDs blinking.

OA47

Volhout
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Joined: 05/03/2018
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Posted: 07:08am 23 Feb 2022

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Soldering of the usb socket? Crystal running?
Edited 2022-02-23 17:09 by Volhout

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OA47

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Posted: 07:41am 23 Feb 2022

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Quote Soldering of the usb socket? Crystal running?

I did test the continuity of the USB connector and I believe it to be OK as I can read the contents of the SD card via that port.

I have not suspected the crystal as the CPU seemed to be doing other things correctly. I will fire up the CRO and have a look.

OA47

JohnS
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Joined: 18/11/2011
Location: United Kingdom
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Posted: 08:06am 23 Feb 2022

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If you have a Linux system, see what dmesg shows as you plug the board in / reset it.

(It will report USB info.)

John
Edited 2022-02-23 18:07 by JohnS

OA47

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Posted: 08:58am 23 Feb 2022

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John I will check it on a Linux system but I dont hold much hope of any info as when I attach to win machine I dont get any report in device manager. Job for the morning.

OA47

OA47

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Posted: 09:02am 23 Feb 2022

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Quote Crystal running?

I checked the crystal oscillator on the CRO and it does differ to a working MMBasic unit so I removed the crystal and temporarily replaced with a surface mount unit and it did not change anything. Maybe I will look at the capacitors and check if the clock is off frequency.

OA47

OA47

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Posted: 12:40am 24 Feb 2022

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Clock/crystal issue seems to be a red herring. After changing the crystal, caps and resistor no change but take off links and exit program mode the clock waveform is excellent. As soon as I put the BT0 link to 3V3 and reset the clock dies.

I am beginning to think that it is the bootloader firmware that is the issue and I dont know of any way to test or correct this.

Edited 2022-02-24 10:47 by OA47

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