BluepillF4 PCBs

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Squonk42
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Re: BluepillF4 PCBs

Post by Squonk42 » Sun Feb 04, 2018 2:07 pm

No problem Ray!

No, this is not off topic, it is always useful to see the whole picture when you are focused on a subject.

There are a lot of low-cost boards available now for tinkering with, and this is a good thing. Among the inexperienced users, the low-cost Arduino micro/mini clones are the most used. For more power users seeking the lowest possible cost, the BluePill boards are a must.

OTOH, there are software-only people who are looking down to hardware stuff, and their favorite platform is then the RPi, because it is relatively cheap and you can find a lot of online resources. You may find more adventurous people looking into Onion Omega 2 or C.H.I.P., far less in BeagleBone Pocket.

Then you have the language-centered developers that feel more comfortable when finding a small board supporting their favorite language (Javascript, Python, Basic) for hardware-related projects.

A cheap, pre-assembled STM32F4 may find its purpose as a high-end MCU/FPU/DSP with lots of IOs, for applications like flight or 3D printer controllers, I think.

And in our case, the most interesting is not the destination, it is the journey! I enjoyed this project because I learned a lot while working on it, and I hope this is the case for others, too.

electrobling
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Re: BluepillF4 PCBs

Post by electrobling » Sun Feb 04, 2018 10:15 pm

For what it's worth, I'd be interested in attempting assembly and test. I've done manual SMT work before, it's tricky to say the least, but not outside of the realm of possibility. The trick with a QFP is to drown it in flux, and allow shorts to happen, but draw solder away with the capillary action of the iron. The smaller parts are not quite so bad. I think if you have got this far, there is no turning back. :)

victor_pv
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Re: BluepillF4 PCBs

Post by victor_pv » Sun Feb 04, 2018 10:48 pm

electrobling wrote:
Sun Feb 04, 2018 10:15 pm
The trick with a QFP is to drown it in flux, and allow shorts to happen, but draw solder away with the capillary action of the iron. The smaller parts are not quite so bad. I think if you have got this far, there is no turning back. :)
I have done the same trick with QFP before, and didn't have any problem. I think the worst for me is holding small components in place when they are all slick from the flux...

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RogerClark
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Re: BluepillF4 PCBs

Post by RogerClark » Mon Feb 05, 2018 2:37 am

I agree the the previous postings about theoretical cost of other boards, vs what most of us actually have to pay for them.

Locally, to get a RPi zero, prices are nearer $15 USD
e.g. This is probably the cheapest I can get hold of
https://core-electronics.com.au/raspber ... eless.html

ESP32 are around $10 USD direct from China (including shipping)


Boards like the BP and MM (and the ESP8266) etc are the only ones I can get in the $2 - $3 range

eggsylah
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Re: BluepillF4 PCBs

Post by eggsylah » Mon Feb 05, 2018 4:59 am

Victor

I've ordered almost all the parts for 5 boards. So if you haven't ordered them yet then please put me down for 5 or 6.
These are on a slow boat from China so they won't be here anytime soon! I will order the remaining ones from Mouser this week. Let me know if you would like me to get some for you. The prices for the AP2114HA-3.3TRG1, LQW2BASR47J00L and MCP73812T-420I/OT seemed better there and the shipping can be covered by another order I am placing. Only the first of these is required but we will need to test the optional parts.

Being a mathematician, I don't have the experience to comment on the layout but I'll try to review the schematic.
I don't have a reflow oven but do have a cheap rework station and stereo microscope so I think assembly will be fine ... but slow.

I have been mainly playing with some baremetal and HAL/LL/CMSIS programing on the STM32L4. So I should look at the F4 boards I have more seriously. Is the idea to work with the STM32GENERIC core ?


Eric

electrobling
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Re: BluepillF4 PCBs

Post by electrobling » Mon Feb 05, 2018 11:27 am

victor_pv wrote:
Sun Feb 04, 2018 10:48 pm
electrobling wrote:
Sun Feb 04, 2018 10:15 pm
The trick with a QFP is to drown it in flux, and allow shorts to happen, but draw solder away with the capillary action of the iron. The smaller parts are not quite so bad. I think if you have got this far, there is no turning back. :)
I have done the same trick with QFP before, and didn't have any problem. I think the worst for me is holding small components in place when they are all slick from the flux...
For a small component, I apply the least amount of solder I can to only one pad. Then I place the component with tweezers and heat that end until it sticks. I go to the other end and make a proper solder join. Then I return to the original end and fix the bad join with a decent amount of solder.

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ahull
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Re: BluepillF4 PCBs

Post by ahull » Mon Feb 05, 2018 11:42 am

electrobling wrote:
Mon Feb 05, 2018 11:27 am
For a small component, I apply the least amount of solder I can to only one pad. Then I place the component with tweezers and heat that end until it sticks. I go to the other end and make a proper solder join. Then I return to the original end and fix the bad join with a decent amount of solder.
+1 .. also good tweezers are a must.

I don't necessarily mean expensive ones, simply ones that have well defined tips that are parallel to each other and small enough not to be too clumsy to handle the component. I have filed away the tips of some cheap tweezers and carefully hammered them flat and parallel to make them more serviceable.

They tend to need some adjusting as time goes by due to the heat from the soldering iron.

Having the eyesight of a 20 year old would also help, but I've checked on ebay, and nobody appears to be selling this. :lol:
- Andy Hull -

electrobling
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Re: BluepillF4 PCBs

Post by electrobling » Mon Feb 05, 2018 11:56 am

I would be interested in trying to build several boards, but I do have the problem of parts. I always order absolutely everything from China, as the shipping costs from the U.S. to Canada are astronomical because the companies like Mouser decline to use the post office. Also the Chinese New Year is upon us soon, and no orders to N.A. will be shipped for an entire month. That might mean a 2 month delay to get parts, assuming that I can source them.

racemaniac
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Re: BluepillF4 PCBs

Post by racemaniac » Mon Feb 05, 2018 12:46 pm

ahull wrote:
Mon Feb 05, 2018 11:42 am
electrobling wrote:
Mon Feb 05, 2018 11:27 am
For a small component, I apply the least amount of solder I can to only one pad. Then I place the component with tweezers and heat that end until it sticks. I go to the other end and make a proper solder join. Then I return to the original end and fix the bad join with a decent amount of solder.
Having the eyesight of a 20 year old would also help, but I've checked on ebay, and nobody appears to be selling this. :lol:
Thank god i got my eyes from the good side of the family XD
my sisters have to wear glasses, while i'll probably have eagle eyes till i'm 60 ^^

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ahull
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Re: BluepillF4 PCBs

Post by ahull » Mon Feb 05, 2018 3:09 pm

racemaniac wrote:
Mon Feb 05, 2018 12:46 pm
ahull wrote:
Mon Feb 05, 2018 11:42 am
electrobling wrote:
Mon Feb 05, 2018 11:27 am
For a small component, I apply the least amount of solder I can to only one pad. Then I place the component with tweezers and heat that end until it sticks. I go to the other end and make a proper solder join. Then I return to the original end and fix the bad join with a decent amount of solder.
Having the eyesight of a 20 year old would also help, but I've checked on ebay, and nobody appears to be selling this. :lol:
Thank god i got my eyes from the good side of the family XD
my sisters have to wear glasses, while i'll probably have eagle eyes till i'm 60 ^^
All bets are off when you hit 50 ;)
I had pretty much perfect vision till I was in my late forties, I now use reading glasses and complain about the writing on packaging, but I can still spot an eagle at 1000 yards.
- Andy Hull -

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