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Waveshare Core


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On 06/02/2018 at 10:20 AM, FantomXR said:

My prototype-PCB arrived yesterday. I set up my reflow oven and gave it a go. I'm very happy with the result. LQFP100 is really small. But it's working! Apart from some changes I needed to make on the 3.3V power supply, it seems that I have the minimal circuit working. :-)

Ahah, finally it was quick!
Better to open a dedicated new topic. Add some explanation of what you did, mostly the available ports.
Just to know what changes are made.
If the MIOS32 can be used as it is.
Just an idea... if it is not too far from what you need to do, if you have to reduce the ports of the MIOS32 better they correspond to those that exist on a Core MIOS8;)

Best regards
Bruno

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  • 3 weeks later...
4 hours ago, Zam said:

Hello

Any drawback with the waveshare core that use VE 512k flash across the 1M for the VG (ST disco) ?

From TK.: "512k should be acceptable. Currently 400k are allocated, but in the past always RAM was the limitation, and not the flash." This is referring to the SEQ app.

I imagine that the chips will also move to the VGT6 at some point.

 

4 hours ago, Zam said:

Flash is just for the MIOS bootloader right ?

I will certainly need compact core soon, waveshare look the perfect footprint.

Best

Zam

I have spares, just PM if you need.

 

 

 

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  • 5 months later...
  • 3 weeks later...

Hi Bruno,

As the connectors are not intended to stack, I suggest to use paddle connectors on both of wCore/USB. Both installed on the top of the PCB and wired straight through. This works well as seen in Peter's video. Maybe other connectors are possible (?) but not necessary here I think. 

Does that answer the question?

Best,
Andy

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  • 3 weeks later...

@latigid on @Hawkeye

Hi Andy, Peter,

I want to reuse your rectangle leds in my project, because they are available on your webshop.
You share the resistor value for each color on the website but only @5V.
Maybe you did the same @ 3.3V (which is the voltage of the SD_RES).
Could you share it? I know I can calculate it based on values@5V but I'm a lazy beta tester ;)

Thank you
Bruno

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@Antichambre

Hi Bruno,

Thanks for considering to use them, just plugged the 5V data in a LED resistor calculator, derived the "diode threshold voltages" and calculated a bit. While i can't live-test at the moment i'd recommend to test with these values:

(Edited)

120R@3.3V for blue
150R@3.3V for white and green
180R@3.3V for orange
220R@3.3V for red

The LEDs are efficient, most are relatively bright already at 2mA, will saturate in brightness somewhere below 10mA, you can definitely test with a variety of resistors for your desired target brightness. 

Many greets,
Peter

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Aren't the GPIOs used as LED outputs already at 3v3? So where are the current values derived from? E.g. the Res/SD board specifies 1k for each in the BOM tool. 

? don't really like giving resistor values for LED brightness, as it's always so subjective. Starting values, sure, but you can always season to taste.

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Fully agreed, brightness perception is highly subjective!

The 5V values were deduced on breadboard with a DMM measuring current @5V. The 3.3V values above were just calculated with an online tool from the 5V values and are not tested at all.

Regarding SD-RES: the LEDs are efficient enough to light up as signalling LEDs with 1K resistors - we don't want to illuminate the room from the back of the SEQ :).

Also, the "brightness curve" is highly non-linear. I.e. a such a 4x3x2mm green LED will surely light up already fairly brightly at 1mA, and will by far not be 10x "dimmer" than at 10mA.

Many greets,
Peter

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Just now, latigid on said:

Aren't the GPIOs used as LED outputs already at 3v3? So where are the current values derived from? E.g. the Res/SD board specifies 1k for each in the BOM tool. 

??!... humm
I didn't watch in the BOM tool.
Res/SD board specifies approximately(~)1K in dokuwiki. I was looking for more precise value. So. Sorry

Just now, latigid on said:

? don't really like giving resistor values for LED brightness, as it's always so subjective. Starting values, sure, but you can always season to taste.

Agree. but . Usually each color needs its own value to get a homogeneous brightness. We all know that, objective so ;)
Thought you already made some tests to get the good looking pictures of the leds on your website. Bref. :decayed:

Thank you both
Bruno


 

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Nah, it's not enlightened, i mean the LEDs hopefully are, but us... not yet :)

The RES-SD BOM resistor values (1k) came from the original wiki RES-SD docu and seemed to work out for my initial RES-SD tests with these LEDs. No big care was taken for total brightness equalization, just a look if moderate-brightness indication works properly. So, if there are updates to these resistor values, please shoot :).

The resistor values listed in the shop for a 5V source were more or less trimmed by experimentation to achieve similar brightness for all multi colored LEDs, and primarily done to be able to take a good photo. As in this scenario the LEDs are a bit brighter and are driven "hotter" than for the RES-SD case, i also measured the LED currents to make sure, that no LED exceeded a two digit milliampare value. The recommendation should be far away from limits (being at 20mA or such).

But, as the brightness curve of these LEDs is really highly nonlinear and the LEDs begin to light up at very low currents already, probably using the same resistors everywhere will not result in a totally different picture than seen in L-X-01 for example in the shop:

6ce08c4a5c7043ecbf53a61b3032d67f.jpg

In the end, and as Andy said, you've just got to test and fine-tune to your preferences! :)

Many greets,
Peter
 

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