[Solved] Shield Shield and SPI Level Conversion (or lack thereof)

Hardware
1

I am closely looking at Shield Shield and at it’s the level shifters. The online description seems to indicate the 3.3V to 5V level shifters are only connected the I2C lines. Can someone confirm?

My project uses SPI to an existing Arduino shield which should require 5V SPI (unless I’m missing something). Can someone suggest the best course of action to interface to SPI using the shield shield?

Is that correct answer, wire up the SPI through the currently unconnected extra level shifter in the corner of the Shield Shield? I’m trying to make sure I’m following everything correctly.

Lastly, my board happens to need some non-SPI lines as well. I believe the Particle’s 3.3V GPIO is 5V tolerant, so I can wire up the MISO line (and other Arduino pins) direct to Particle and not use one of the level shifters? How am I doing here? ? :smile:

Thank you for your help,

Ed

2

This schematic shows that there is level translation at least for A2/SS, A4/MISO & A5/MOSI, no idea why not for A3/SCK

https://github.com/spark/shields/blob/master/photon-shields/PDFs/Schematics/shield-shield-v301.pdf

3

Thank you much.

Very mysterious the lack of SPI clock. The second SPI interface does appear to have clock converted as well D4/SCK.

4

Maybe @mohit or @BDub can shed some light on this?