Is it possible to build an add-on card that has mini PCI-E slot, SIM slot and LED and that can be attached to Raspberry Pi 2 GPIO header?
It would save me one USB port and it would be more neater and compact than having 3G USB modem dongle sticking ugly out from Raspberry Pi 2. Note: I'm total new to electronics.
This guy connected USB port directly to WWAN module:
But Raspberry PI GPIO header has no USB D+ and USB D- pins so what to use for those? UART TX/Rx pins ? I2C1 SDA/SCL pins ? Do I need USB-to-Serial UART/I2c chip ? How many resistors, what type and where to put them?
Heres Raspberry PI 2 GPIO header:
So what parts would I need (besides Mini PCI-e connector and female header for GPIO) and how to connect them?
Or if it is not too much trouble, could someone post Fritzing file that I could study?
Note: Im not trying to add PCIe devices to Pi. I try to use WWAN 3G Module that uses USB 2.0 for signaling (like Chris Stratton mentioned) and all the modules just happen to be in Mini PCIe form.
Pi GPIO can't be directly connected to pins 36 and 38 in Mini PCIe slot (because GPIO lacks USB D+ & D- pins).
So can I use USB-to-UART (or I2C ?) bridge chip or not ?