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Brymen IR connection protocol - Anyone sniffed it yet?

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t1d:
@ Sairus - I have not been able to sleep, tonight, so I have worked on your design. I have made the first draft of the Eagle schematic and board layouts. I have attached jpeg images for you to review. If you see needed corrections, let me know and I will fix any issues. (I already see that I left the capacitor values off of the schematic. I will correct this.) When you have given your final approval, I will post the Eagle files and pdfs, as I did for Jadew.

I determined that my confusion over the PL2313 being on the board was from not understanding that the UART-USB box on the schematic was just to represent this off-board component. I was further confused by the big capacitor, below the PIC12F683 in the photograph; I thought it was the PL2313.

Once I had this straightened out in my mind, I was able to follow your board layout. You came up with an elegant design and did well with avoiding cutting off access to ground.

There are a few minor differences to my representation of your work:
- You used 5mm holes for the IR components; I used 4mm holes. This is from the early design work of others, who determined that the smaller holes made a nice seat for the convex lenses and kept these lenses from being able to be scratched by the DMM lens. The smaller hole also helps prevent seepage, when potting the components in epoxy. However, if you would rather have 5mm holes, I would be glad to change them.
- All resistors and capacitor footprints are SMD 1206. (If you specified SMD IR components, your design could be fully SMD. This would reduce the interface profile. That would be very cool.)
- Please confirm that the value for the resistor for the phototransistor is 200K.

I am enjoying working with you, very much; you have excellent skills. It is great to be making another friend on the other side of the world. Hurray for the internet!

EDIT: You might want to swap the location of C1 and C2, to place the smaller cap closer to the chip pin. Also, I had made other minor changes to your board, that I forgot to mention... I added an independent ground pad, whereas you had attached the ground wire to a cap ground pin. And, I put both caps at the top of the board. This placed the cap that was below the chip a little closer to the pin, decreased the distance between the voltage coming onto the board and then being smoothed and removed a trace from underneath the chip, improving noise considerations. I have already added the cap values to the schematic.

t1d:
@ Sairus
Would these work?
Mouser.com
IR Emitter - Part Number: 782-VSMB2000X01
IR Phototransister - Part Number: 782-VEMT2000X01

JackM:

--- Quote from: t1d on June 27, 2016, 09:39:42 am ---@ Sairus - I have not been able to sleep, tonight, so I have worked on your design. I have made the first draft of the Eagle schematic and board layouts. I have attached jpeg images for you to review. If you see needed corrections, let me know and I will fix any issues. (I already see that I left the capacitor values off of the schematic. I will correct this.) When you have given your final approval, I will post the Eagle files and pdfs, as I did for Jadew.

--- End quote ---

After looking at the board layout, I was wondering about the placement of the +5V, ground and RX pads. They seem to be placed in sort of random spots on the board. It would be nice if they were all together, and perhaps the pads could be changed to allow for adding a surface mount 0.1" pin header on the board? I was thinking something like this: http://www.digikey.ca/product-detail/en/harwin-inc/M20-7870246/952-1771-ND/3727740
I think it would make connecting the lockstep board to a USB cable a lot simpler.

t1d:

--- Quote from: JackM on June 27, 2016, 03:00:06 pm ---After looking at the board layout, I was wondering about the placement of the +5V, ground and RX pads. They seem to be placed in sort of random spots on the board. It would be nice if they were all together, and perhaps the pads could be changed to allow for adding a surface mount 0.1" pin header on the board? I was thinking something like this: http://www.digikey.ca/product-detail/en/harwin-inc/M20-7870246/952-1771-ND/3727740 I think it would make connecting the lockstep board to a USB cable a lot simpler.
--- End quote ---
Hey, Jack,

Thanks for working on this with me... Good observations... I like the connector idea.

The wire pads were placed with some intent... proximity to pins, having the cable centered over the board, and, in the case of the ground, making sure that it was not cut off from any component's ground pin, by a trace. The cable does not necessarily need to be centered, but that is what is typical and it would make twisting the board into the bracket easier, by some minor amount, because it is over the center axis of the board.

5V and C1 (I suggest C1 be the 100n resistor) could trade places, though the present arrangement has the advantage of less trace between C1 and the pin (reduces the trace/antenna length.) RX could be turned 90 degrees and GND could be worked in below RX. With a little tweaking, all off the wire pads could be lined up on the left side of the chip, just slightly off axis.

If you use Eagle, I would be glad to send you the working files and you can play around with it. I would find it fun to have someone to work with on the "magic art" of board layout design.

Ultimately, I just want Sairus to make any final decisions and for him to be pleased with his creation.

I was going to post a cleaned-up revision of the board, but I see another mistake. So, maybe in a little while.

Thanks so much for helping. Please remember to let me know about the Eagle files.

t1d:
Sairus's Board
v2
Cleaned up some details to get the ground plane to fully flood the component zone.

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