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matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10565

Posted: 02:25am 03 Nov 2017

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This is a new PCB design for the 64-pin Micromite eXtreme (PIC32MZ2048EF%064). The board has a RTC, IR receiver, buzzer, sound output, SDcard and PIC16F1455 USB adapter/programmer together with the Pi standard 40-pin header.

Pins 35 and 40 are selectable between I2S and SPI functionality using a header. The Pi uses the same pins for both functions.

The format and component placement is exactly the same as the Pi 3 and should fit inside any Pi 3 case

All comments and suggestions welcome before I go to copper. The copper fill areas are deliberately omitted for clarity.

The PCBs are 85x56mm double sided and all spacings meet the cheapest production specs so 10-off PCBs from PCBgogo are currently only $5 + postage

2017-11-03_121956_schematic.pdf

JohnS
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Joined: 18/11/2011
Location: United Kingdom
Posts: 4126

Posted: 03:14am 03 Nov 2017

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In the schematic pin 14 of what I think is the PIC16F1455 (U4 or is it meant to be IC1?) looks not to go to GND.

Sorry if I'm not reading it right. Perhaps putting GND nearby means it does...

JohnEdited by JohnS 2017-11-04

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10565

Posted: 03:26am 03 Nov 2017

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John

Thanks for looking so closely. The way DesignSpark works is that you can pick which net the pin connects to and then, optionally, ask for a label. That whole net segment is part of GND but I agree the schematic isn't clear.

LouisG
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Joined: 19/03/2016
Location: Australia
Posts: 129

Posted: 04:45am 03 Nov 2017

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I'm not familiar with the abbreviation used for Count/Freq input.
How many such inputs make it to the 40-pin header? All four? (Assuming the MZ has four like the MX has.)

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matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10565

Posted: 04:50am 03 Nov 2017

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Quote How many such inputs make it to the 40-pin header?

2 on the 40-pin + 1 for the IR receiver - 1 missing is this an issue?

LouisG
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Joined: 19/03/2016
Location: Australia
Posts: 129

Posted: 05:25am 03 Nov 2017

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No, not presently an issue. But I consider Count/Freq inputs more valuable than "regular" DIs. So easy to connect 555 oscillator moisture sensors, paddle-wheel flowmeters, etc. I once had to use all four frequency inputs so it's something I question if all available I/O are not brought out for use.

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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9749

Posted: 11:59am 03 Nov 2017

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Nice work, matherp.

Smoke makes things work. When the smoke gets out, it stops!

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