Stacking Arduino Shields

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AMDlloydsp
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Re: Stacking Arduino Shields

Post by AMDlloydsp » Wed Nov 26, 2014 2:11 pm

Mini-B footprint in the "datasheet" on this page:
SMT:
https://www.sparkfun.com/products/587
Through-hole:
http://www.newark.com/multicomp/mc32599 ... dp/46P5313
Lloyd



basicchip
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Re: Stacking Arduino Shields

Post by basicchip » Wed Nov 26, 2014 3:53 pm

I am assuming the connection on the right is for the USB breakout. That I don't understand, it has 5V and GND connections, but why connect the other 3 lines. 2 are normally for data, which is a differential signal that requires special decoding, and the 3rd is normally a PWR/GND connection used to identify whether it is host/device/OTG. If that is the case those should not be connected to your i2c lines.

Maybe you are just using the USB cable as a cable, though personally I wouldn't recommend doing that, to tempting to plug it into a PC sometime and screw up something. For nonstandard cables I tend to use RJ-11 or RJ-45, as they are easy to make and don't require any sort of a breakout board and can be made to lengths longer than USB.

danlee58
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Re: Stacking Arduino Shields

Post by danlee58 » Wed Nov 26, 2014 6:37 pm

Yes, I am using a USB cable to make the I2C connections. I'll look into using RJ-11 or RJ-45.

I need 5 pins. Most RJ-11 Cables are pinned for 4 pins. I'll have to go with RJ-45, although I have a number of USB Mini-b connectors. Either way I need a pin out for whatever connector.

basicchip
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Re: Stacking Arduino Shields

Post by basicchip » Wed Nov 26, 2014 7:13 pm

For i2c you should only need 4, PWR, GND, SDA and SCK. Many USB cables only have 4 pins and a shield.

danlee58
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Re: Stacking Arduino Shields

Post by danlee58 » Wed Nov 26, 2014 9:14 pm

I need a 5th pin for a logic switch input to the SuperPro. USB Mini-b has 5 pins, and RJ-45 has 8 pins.

Don't RJ-45 cables swap some pins between ends, like RS232 cables? I need 1:1 wiring in the cable.

danlee58
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Re: Stacking Arduino Shields

Post by danlee58 » Thu Nov 27, 2014 3:12 pm

I got the Display working using USB Mini-b cable and connectors. At this point I see no reason to abandon USB as the interface. My connections follow the USB standard, except I have Clock & Data lines instead of Data+ & Data-. The 5 Volt Power & Ground connections are the same as USB.

I would like to bring the Power Pins from the Coridium SuperPro, the Programming Jumper pins and Reset pins up to this new board, that will be the top board in the stack.

I found the footprint for the USB Mini-b connector, but the dimensions are all metric. I am not sure that I can add that footprint to my layout with the software that I have. I will leave the holes for the USB Breakout board, as a precaution.

basicchip
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Re: Stacking Arduino Shields

Post by basicchip » Thu Nov 27, 2014 3:23 pm

RJ-11 connectors can be bought with 6 connections, though you are correct that 4 is most common used for phones. Those are typically straight thru.

RJ-45 can have pin swaps or be straight through, which I believe are most common. The reason I like them is you can buy a crimp tool for very little, Radio Shack use to carry them, and that and a bag of connectors and a box of cable you can make most anything you need. They are very reliable and pretty sturdy, as ATT invested a lot in their design and ease of use.

AMDlloydsp
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Re: Stacking Arduino Shields

Post by AMDlloydsp » Thu Nov 27, 2014 8:21 pm

I found the footprint for the USB Mini-b connector, but the dimensions are all metric. I am not sure that I can add that footprint to my layout with the software that I have. I will leave the holes for the USB Breakout board, as a precaution.
---------------------
25.4mm/inch. That's all you have to know to convert them, one to another.

I have plenty of metric connectors on my 'inch' layouts. Some, I had to "re-lay" with my own pads and holes, rather than using a library component. It's really not a problem to do in almost any layout software you can name; it's just a lot more work than clicking on a library shape.

Lloyd

AMDlloydsp
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Re: Stacking Arduino Shields

Post by AMDlloydsp » Fri Nov 28, 2014 12:26 am

RJ-45 can have pin swaps or be straight through
-------------
For telco style connections, both the 568A and 568B configurations (most common) have all "straight-through" connections, but the orange and green pairs are on different pairs of pins in the two standards. Either is used interchangeably for Ethernet XX-base-T wiring. The swapping of color pairs does not affect the straight-through arrangement, only the visual coding of those pairs.

There are also rare "cross-over" and "rollover" pinouts in which some signals are crossed. You seldom see those except inside a switch-room. Well... except in my shop, perhaps, where I have made up "passive hubs" which are nothing more than Ethernet cross-over cables, for the times when I encounter an old Ethernet interface that doesn't know how to swap pairs dynamically.

RJ-45 was designed for easy installation and durability when not frequently plugged and un-plugged. The built-in crimped strain relief helps with small amounts of cable flex, but the male connector itself with it's scant gold flash and thin plastic locking tang, is not made for frequent use. The tang nearly always breaks off after a few dozen release presses, and without anti-ox gel in and on the mated connection, the plated spring wires used in the connector will corrode in a year or so of exposure to high humidity.

I'm not fond of RJ-45 connectors in equipment exposed to high temperatures or high humidity, nor for frequent re-connections. But, then, USB connectors from the Orient also have very little gold on them, and exhibit the same corrosion problems with time.

However, they are designed with broader, more-compliant connector leaves with a larger contact area than has an RJ-45, and will handle frequent re-connection better.

Lloyd

danlee58
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Re: Stacking Arduino Shields

Post by danlee58 » Fri Nov 28, 2014 1:48 pm

Bruce,

I need the x,y coordinates for the SuperPro power connection (J4), the Boot jumper connection (J11), and a Reset pin. I want to bring those pins up to my board.

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