F405 & F411 versions of the BluePill

What are you developing?
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Squonk42
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Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Tue Feb 13, 2018 1:12 pm

Sorry, I didn't know about Andy :lol:

Of course he was right!

racemaniac
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Re: F405 & F411 versions of the BluePill

Post by racemaniac » Wed Feb 14, 2018 10:36 am

@squonk, the boards you sent me just arrived, i'll try to assemble one tomorrow :) (valentines day is not the best day to start on such a project ^^')

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Squonk42
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Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Wed Feb 14, 2018 10:50 am

OK, great! I understand your priorities :lol:

I found a schematic bug on the RESET button: the NRST is active low... It should be connected to the R6 pull-up by default, and not to the C15 debounce capacitor, i.e. to the pin 1 or 3 of tactile switch S2, not to pin 2 or 4!

Otherwise, a single red led fitted in the 1616 RGB footprint, mounted with R3 only (R14/R15 not mounted) works as expected, i.e. like the single LED on PC13 from he original BluePill. I lowered R3 to 150R because I had no 510R on hand, but both value may work, just no as bright.

R1 pull-down resistor on PB2 (BOOT1) is OK, as well as BOOT0/USER button and connection to PB8 is also OK.

Next step (maybe not tonight!) is to test the USB load switch U4 and the Schottky diode D3, then mount the decoupling capacitors and the STM32F405 itself and make the LED blink!

Then the 2x crystals one by one, and test the SD Card. Battery charger option is last in my list, as I don't have the parts yet).

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Squonk42
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Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Wed Feb 14, 2018 12:48 pm

Squonk42 wrote:
Wed Feb 14, 2018 10:50 am
I found a schematic bug on the RESET button: the NRST is active low... It should be connected to the R6 pull-up by default, and not to the C15 debounce capacitor, i.e. to the pin 1 or 3 of tactile switch S2, not to pin 2 or 4!
Simplest fix: cut the NRST trace on the bottom face just before the via under the RESET tactile switch and add a wire on top face between R6 pad 2 and the NRST header pin.

racemaniac
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Re: F405 & F411 versions of the BluePill

Post by racemaniac » Fri Feb 16, 2018 3:57 pm

Ok, i've been assembling one of the boards i received from squonk, first remark: we probably best ditch the ground pads of the buttons. After assembling it, i had a short between 3v3 & GND, after removing the usual suspects, i found it was due to the boot0 button. Looking at the footprint, it has this tiny ground pad right next to a 3v3 pad. The slightest misalignment of the button, and it shorts them...
If this is meant something cheap & easy to produce, i think those ground pads are just too dangerous to leave there (and they don't really serve any use anyway i think?)

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Squonk42
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Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Fri Feb 16, 2018 9:33 pm

I think their only purpose is to maintain the button. But given their tiny size, I doubt that any effort will ever be applied, so it is probably safe to suppress them altogether.

I soldered the USB load switch and related components, but I had no time yet to test it and the Schottky diode.

What I have left to solder and test are the CPU with all its decoupling capacitors, then the 2 crystals and capacitors, the SDIO Card connector and decoupling, and the optional battery charger circuit.

Apart from my bad solder joint above and the wrong polarity for the RESET button, nothing else to report for the moment.

victor_pv
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Re: F405 & F411 versions of the BluePill

Post by victor_pv » Sat Feb 17, 2018 1:20 am

I got a nice box from Mouser today with all the components I was missing. Tomorrow I hope to cut the stencil, reflow a board with all top components except the MCU and check it all up for shorts or anything like that, then solder the MCU.
Other than the track we need to cut and watching out for shorts under the buttons, anything else so far?

racemaniac
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Re: F405 & F411 versions of the BluePill

Post by racemaniac » Sat Feb 17, 2018 8:13 am

nope, nothing else afaik
Good news from my board: just made contact to it via st link :). Haven't done much more testing on it, but it has everything mounted on the top side except for the 2 buttons (and resistor/cap of the reset button due to its issues)
(and due to a lack of ferrite beads, i replaced them by a piece of wire ^^)

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Squonk42
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Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Sat Feb 17, 2018 10:54 am

No, nothing else.

Very good if it is responding the STLink!

Did you take into account my remark regarding the crystal capacitors that were swapped? It will probably be the most tricky part to adjust if we want to have the crystals starting reliably.

racemaniac
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Re: F405 & F411 versions of the BluePill

Post by racemaniac » Sat Feb 17, 2018 12:19 pm

Squonk42 wrote:
Sat Feb 17, 2018 10:54 am
No, nothing else.

Very good if it is responding the STLink!

Did you take into account my remark regarding the crystal capacitors that were swapped? It will probably be the most tricky part to adjust if we want to have the crystals starting reliably.
nope, haven't taken that into account yet, and indeed, swapping them won't be easy ^^'
i'll see what i can do to get around it

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