https://raspberrypi.stackexchange.com/q/3475/24217

is a quite interesting question that I was not able to fully answer for my rPi Model B+ v.2 - the one with the extended 40pin connectors.

To avoid this beeing a useless clone of the original question, I am going to be more specific:

  - Raspberry Pi Model B+ with 40pin connectors only
  - goal is to have something like ttyAMA1 or ttyS0 **AND** ttyAMA0 -> two seperate com-Ports
  - **NO** USB-Adapters
  - **NO** IC-Based Shields
  - some resistors or caps if needed would be ok
  - a sound explaination on why a second com-port on the B+ is not possible is ok as well!

**Why do I think this should be possible?**

According to the Documentation of the [BCM2835][1] (Page 10 & 175) and these Pages:

http://elinux.org/RPi_BCM2835_GPIOs#RXD1

http://lavalink.com/2012/04/more-on-raspberry-pi-serial-ports/

there is a _mini UART_ and the _PL011 UART_ and I eighter miss something or just not understood why this second UART is unavailable by default.

My rPi is otherwise configured good so far and the _ttyAMA0_ works fine.

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So, has anybody an idea how to activate _ttyAMA1_ or the reason why this is not possible? 


  [1]: http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf