Reef-PI_<PCB's>

wykat

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Introduction

Based on the Fritzing designs for Reef-PI, I’ve developed some PCB designs to operate with the Reef-PI software. Based on an early statement from Ranjib that he wanted to have customizable Reef-PI software to support a wide range of environments, this has been one of the main drivers for these PCB designs. At the same time I’ve tried to minimize the size of the individual modules to fit the Raspberry PI outline.

The picture below shows a Raspberry PI with 2 functional PCBA’s stacked on top of it.
upload_2018-11-29_12-28-30.png



This combination with all components installed provides following functions to the Reef-PI software:

Middle board (I call it Reef-PI_HAT v1.0)

· Interface to up to 16 external relays (110/220VAC)

· Interface to up to 2 12V motor controllers (technically bi-directional)

· Interface to up to 2 optical ATO sensors

· Interface to DS18B20 temperature sensors

· Interface to an I2C bus to support multiple Reef-PI_<PCB> stacked boards

Top board (Reef-PI_PWM v1.0) NOT YET RELEASED DUE TO MISSING COMPONENTS

· Interface to up to 16 0-10V PWM controllers

· Interface to additional stacked I2C Reef-PI_<PCB> boards.

Instead of using the connectors as shown, it’s also possible to use connectors in the housing and use wiring directly to the PCB board. A disadvantage of this is that’s it’s more difficult to take the device apart with all the wiring, so in case you do, use longer wires to have some flexibility.

Presently I’m working on a 4 port ORP/pH module based on Roberto_B’s design at the same size as the PWM module, This is still in a design phase. The Reef-PI_HAT has been tested by me and others on the Reef2Reef forum. The PWM module seems to function but without having any light controllers (yet), any feedback is welcome.

The Reef-PI_HAT is simple to be assembled, even easier than using Fritzing boards since all the wiring between components is already integrated in the PCB design. The building guideline documentation also describes which components can be left out when certain functions are not required.

The Reef-PI_PWM module is more difficult to assemble as it uses one TSSOP electronic component (PCA9685) which is not available in through hole technology. Alternatively it’s possible to use an external PCA9685 module as described in Ranjib’s installation guides, just connect the board to the I2C interface of the Reef-PI_HAT or other stacked Reef-PI_<PCB> boards.

The Reef-PI_ pH board (still in design) is almost completely based on SMD components and will therefore become the most difficult one.


The PCB files and documentation can be found at: https://github.com/vandegraaf/Reef-PI_PCBs

PCB’s can be ordered from a number of PCB prototype suppliers. Basically they only need the <module>.zip file. Normally 10 pieces can be ordered for the same price as 1.

Roadmap:

· Build latest PWM module to verify functionality (lost required transistors)

· Complete the assembly guideline(s)

· Finish (4 port?) ORP/pH design

· Reef-PI_HAT v2 (5V supply to Raspberry PI, more motor and ATO interfaces, external LM2596 module, watchdog interface?)

· Power module, still in conceptual design and will require the Reef-PI_HAT v2 (UPS, alarm, watchdog, LM2596)

· MCP23017 module which would allow additional Input/Output functions. The MCP23017 is presently not supported by Reef-PI, but Ranjib indicated it’s in his picture. This module together with the Reef-PI_PWM module would basically technically unlimit the number of functions to be controlled via the Reef-PI software (>1’000, depending on functions used). Not started

· And of course a 3D printable housing, still in conceptual design

· And not to forget to order my reef aquarium!

Note: This is not a commercial project, if somebody wants to assemble these boards to support other forum members, feel free.
 
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rushbattle

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Once complete, would you mind if I had these designs converted to all SMD components so they can get assembled by pick and place and reflow shop? That’s a competitive market now and prices are coming down. I would be happy to organize group buys for the finished products after testing them.
 
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wykat

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Once complete, would you mind if I had these designs converted to all SMD components so they can get assembled by pick and place and reflow shop? That’s a competitive market now and prices are coming down. I would be happy to organize group buys for the finished products after testing them.
that's OK. As written, I made these boards as no commercial project and to be shared with others. The designs are made in KiCAD which is open source as well and all files including schematics are on Github.

I hope it contributes to Ranjib's Reef-PI's success in order to have more people, also without electronic knowledge, to benefit from available components.

With SMD however main challenge will be the connectors but that's a topic on it's own. I think housing/connectors are an interesting topic to look at (salt water protection, air cooling, etc.). This has been one of the reasons to have all connectors only on 2 sides (bottom/front in my present view).
 
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wykat

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Can't speak about US PCB suppliers, presently PCBWAY is my preference after JLCPCB failed to deliver a shipment via 'normal' shipment, only the stencil arrived, but no PCB's. They claimed they always send them together, claim they have been send, but have no proof. Got my money back via Paypal.

PCBWAY is more accurate and discovered a conflict in my PWM module design (JLCPCB didn't complain) which is related to some outlines in the connectors (very minimal). Don't know how to get this resolved in Kicad, but already know how to correct it in the text file. Presently just use the drill file as correct to PCBWAY, then it's ok.

Expect the missing transistors by Monday/Tuesday, they are on their way, then we can continue with the PWM module.:)
 

crusso1993

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Although not a solution for all of us, it would be cool to convert a 3D printer into a PCB printer and do our own boards. Maybe some of our members with the 3D printers can give this a go and make a video. Just a thought...
 

rushbattle

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Although not a solution for all of us, it would be cool to convert a 3D printer into a PCB printer and do our own boards. Maybe some of our members with the 3D printers can give this a go and make a video. Just a thought...
This would be super cool to work out details through prototyping. It would allow rapid iterations for testing which would really speed development time. No idea on the cost though. It might still be cheaper to go with a very cheap PCB manufacturer knowing that they are prototypes and super high quality is not needed.

My personal vision is to end up with professionally manufactured PCBs populated by professional assemblers (with pick and place and reflow process for low cost) conformal coated for longevity. As noted above that will be challenging for connectors and cooling.
 
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