Looking for electrical review on my project

[Constantin]

Hi,

Attached below is a revised BRD file based on the one you sent me. There seems to be an ERC issue between the SCH file and the BRD file surrounding the SCL/SDA pins for the I2C bus. Not sure what the issue is, which one was right (schematic or BRD file) so I just revised the BRD file.



Here is what I came up with in an hour or two. Note the much lower number of cuts across the GND plane and the revised location of the battery holder. Kudos on the quick implementation of the Yaimichi connector, it's a great little micro-SD card holder, if only Digikey also chose to carry it.

Also, please note how I moved all through-hole components to the other side of the board, with the SMD components only mounted on the top side. Gives you more room to assemble / solder the thing and there is usually no good reason to not move the SMD components to the underside of the board.

View attachment MotoDisplay v0.1.zip

 

[EK701]

Wow, that was a major redesign of the PCB! Thank you for your efforts!

 

[Constantin]

No worries. Glad you liked the suggestions.

FWIW, I would go with one of the Teensy eagle libraries that omits the whole stack of center pins. You're not using them, so why have mounting holes for them? See the Teensy libraries posted on this site.

Since I don't know what the connector directly below the teensy with the SPI and I2C connections is for, this may or may not be a useful suggestion: if the connector is meant for an external SPI / I2C sensor, daughterboard, etc. then I would also put a 3.3V pin on that connector.

If, on the other hand, that connector is mainly there for diagnostic purposes (i.e. a salalae logic interface) , then I would consider eliminating it. You can buy pin headers that are long for the teensy and thus allow you to plug the Logic probes directly into the teensy pins. That would eliminate potentially a number of the vias I put in.

Last but not least, if the connections on that pin header are going 'off-board' then keep that distance short. I2C was conceived for bus lengths of tens of cm or less. People certainly have gotten away with longer lengths but eventually the bus either becomes buggy or you need to add additional specialized chips that allow the bus to function despite being out of spec.