Author Topic: PCB Review Request: Quad 14-segment display breakout board.  (Read 378 times)

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Offline tylerssims

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PCB Review Request: Quad 14-segment display breakout board.
« on: December 02, 2022, 09:23:16 pm »

This is the first PCB I've laid out myself so go easy:) It's a breakout board for 4 pairs of Adafruit 14-segment displays- which are already mounted onto driver boards. I am just breaking out the SLC, SDA, 3.3V and GND pins from each module to solder pads, which will connect to an ESP8266 on another PCB. The SLA and SDA are being connected to the ESP8266 pcb with about 6 inches of 26awg wire. My signal traces are 0.3mm w/ 0.3mm vias, and my power traces are 0.5mm w/0.5mm vias.

The test points are just my solder pads.

I put the solder pads on the back because the wires need to come off the back of the board.

I have a few questions:

-My ESP8266 PCB already has a pull up for the I2C. Will I need to add another resistor given the extra capacitance in my board + wires? I figure that I can always add one inline with the 26awg wire if I needed to after the fact.

-I tried to keep the pads for my SLA and SDA wires as small as possible, do they look ok?

-Can I combine SLA and SDA traces like I have done? Or am I completely wrong? The displays all have individual I2C addresses.

Thanks for the help!

14-segment displays:

Online Doctorandus_P

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Re: PCB Review Request: Quad 14-segment display breakout board.
« Reply #1 on: December 02, 2022, 11:27:42 pm »
The PCB is a bit too simple to be worth a review...

I would either mount these displays to a some front panel or just a piece of wood and then solder some wires for power and I2C to it, or buy separate displays and HT16K33 IC's and design a PCB for it all.

The 16k33 also supports multiplexing with a key matrix, which is nice for some front panel project and you can make some use of that.

I2C wiring is not critical because of it's low speed and flanks. Both I2C wires do need a pullup resistor somewhere on the bus though. I2C does not work without those pullup resistors.
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