Thank you for interest in the Intel® Joule™ Products.
I understand that you are interested in knowing the respective operation voltages of each of the interfaces.
In the Intel® Joule™ Module – Datasheet (http://www.intel.com/content/dam/support/us/en/documents/joule-products/intel-joule-module-datasheet.pdf) you can see the following statement:
All I/O signals are 1.8V with the exception of USB and PCIe which adhere to their respective standards.
That document also mentions that the maximum electrical specifications are: 1.89 V and 300 mA.
Also, if you check the Intel® Joule™ Expansion Board – Design Guide (http://www.intel.com/content/dam/support/us/en/documents/joule-products/intel-joule-expansion-board-design-guide.pdf) you can see the following information that confirms the previous statement:
Unless otherwise noted, all I/O signals operate at 1.8 VDC (with the exception of industry standard buses and protocols) each which must operate within their defining specifications parameters.
All module GPIO lines function at 1.8 V levels. Intel® Joule™ expansion board provides appropriate level transition, signal conditioning, and protection for devices on-or devices connected to-the expansion board.
Please let me know if the previous information answers your question.
OK, that all makes sense to me until the very end there when you say:
Intel® Joule™ expansion board provides appropriate level transition, signal conditioning, and protection for devices on-or devices connected to-the expansion board.
Does that mean that the expansion board does level shifting for the I/O lines? I understand now that the Joule Module itself uses 1.8V for all I/O, but if I am using the expansion board can I provide other voltages, or should I provide my own level shifter to go from a 3.3V or 5V logic line down to 1.8?
Sorry for the confusion the previous post may have generated. Let me rephrase the information previously cited:
All I/O signals from the compute module are 1.8 V (with the exception of USB and PCIe).
On the other hand, all I/O signals from the expansion board are 3.3 V (and 5 V tolerant), thanks to the level transition, signal conditioning, and protection for devices.
I hope that answers your question, please let me know if you need further assistance.
As I mentioned before in this post, all I/O signals (keep in mind that GPIO stands for general-purpose input/output) from the expansion board are 3.3 V (by default). So you don’t have to perform any additional configuration.
If you have any other question, don’t hesitate to contact us.
Have a nice day.