Hi Guys, I am Elco Jacobs, the founder of BrewPi, an Arduino and Raspberry Pi based brewing temperature controller. I have just designed a PCB for a BrewPi Spark Shield and I would like to share it with you in hope you have some valuable feedback. Here is some background info to help you understa…

[image] v8dave: What about the matching sockets from Samtec? That would extend it and allow you to dismantle is needed. Just regular headers are already very long. Male + female = 10.83mm. I can combine this with a board to board spacer of 11.1mm to hold the display firmly in place. The only…

@peekay123 I tried the IL9341 straight from the spark Web IDE. Worked like a charm! Only had to change the arguments in the constructor to Adafruit_ILI9341 tft = Adafruit_ILI9341(D4, D5, 0); I set the reset pin to 0, as it is connected to the spark reset pin. The pin is not used in the library, …

Small update: Got SWD debugging working, see my other thread. Display is working fine. Still have to test the touch screen functionality. The 5V linear regulator works, but it generates quite a bit of heat. The board + spark + display draws 250mA. So the LDO has to dissipate (12V-5V)*250mA = 1.75…

If you do go with a switcher, take care to minimize noise/ripple on the output rail. If the switcher produces too much ripple (e.g. poor layout, high ESR caps, etc) you can push the on-core LDO into oscillation. Key symptoms of that problem are very high LDO power dissipation (aka, it gets very hot…

@AndyW , I was thinking something along these lines: http://webench.ti.com/webench5/power/webench5.cgi?VinMin=11.00&VinMax=13.00&O1V=5&O1I=0.8&base_pn=LM2675&AppType=None&op_TA=30&lang_chosen=en_US&optfactor=3 LM2675MX-5.0, with low ESR 47u or 68u output capacitor and 47uH or 68uH coil. This chip …

@AndyW I designed the new version, with the switching power supply. I hope you can look at it and critique my layout. Other changes: Pull down resistors on ACT1-ACT3 Pull up resistor on BUZZ (to 5V, pin is not 5V tolerant, but with 10k resistor). Input cap on ADC changed to 10n 10n input cap on …

Hi Elco, Just a couple comments: C4’s return is quite long… see if you can get that ground connected more directly to the Core’s GND. As a general practice, the planes under L1 should be split in the middle with a gap, vs. shifted to one side like you have it. Or better yet, remove the ground pla…

Thanks for the feedback @BDub . C4 return path is GND pin on header --> bottom plane --> GND pin on spark. It’s not that long? I can place it under the spark core though and it will be shorter. The plane under the inductor is 5V, not GND. The datasheet had the plane split like this in their referen…

Ahh, ok… didn’t see that GND pin on the 3 pin connector. That’s not so bad, but ideally you want both legs of the cap to be between the the input connections and connections to the spark core. If you have a reference design, definitely go for that first. It’s shielded anyway, so no worries… just …

Looking for feedback on brewing shield with touchscreen

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AndyW October 28, 2014, 12:22am 42

Looks good.

Pay attention to the layout with the lm2675.

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Looking for feedback on brewing shield with touchscreen

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