So I had a look into the pinout of a mPCIe Connector (and the pinout described in the PCIE 2.0 Base Specification). But I am not sure which signals are really mandatory to be used as declared by the description of the "standard" pinout and which pins of the mPCIe Module can just be used for any other signal - while still beeing "compliant" to the mPCIe specification?
In other terms: From a Mini PCIe Card I assume that it uses PCIe as the communication "type" (i.e. PCIe physical layer, data link layer and so on...).But have look at this board (just to have an example):
They claim to be mPCIe standard compliant, but acutally don´t use any PCIe signaling? For example they use UART signals on the lines dedicated for differential transmit pair of PCIe. ?
Can anyone assign any function to egde card of a Mini PCIe Modul and claim that it is standard compliant?
EDIT: I found the follwing phrase in the standard: Two primary data interfaces are defined for PCI Express Mini Card: PCI Express and USB System designers may optionally choose to implement slots that support only one of these interfaces and still be compliant to this specification.
--> So If i interpret this correctly, I have answered my question and was a bit too quick in asking here. But to be sure: That means as long as I use USB signals on the mPCIe connector, I am conform to the PCIe standard, although I don´t use PCIe?