user20429: I wan't to send information from my arduino digital pins to another arduino's digital pins like a string, or a char. Can I do this without something like Software Serial?
The reason I am asking is because I am wanting to send information from several serial devices to my raspberry pi from an arduino. Thing is, that Raspberry pi only has one set of UART pins, so I was thinking because I have extra arduino uno's, why not send then information to the arduino and have it write the received information to the raspberry pi's digital pins..
Now that I am writing this, I think I will connect the 2 arduinos via a serial connection, and use software serial to write out to the raspberry pi, in three different stages, to get the information to the pi.
The reason I am using the PI is I want to display this information on a large screen with many different options, in short the GPU capabilities are what I am using the PI for, that and Processing.
Question still stands though, can you send information over digital pins?

user19409: Yes, you can send information to/from your arduino digital pins using a method called Bit Banging. Wikipedia (lots more on Google!)
You can use the Arduino to output as an ad hoc serial port or parallel port. The serial could be asynchronous (UART/RS232/I2C) or synchronous (such as SPI). 
The down side is you will have to write a fair bit more software to send/interpret the data.
From your description I gather that data is only going one way - from the Arduino to the Pi. I personally would bit bang SPI as I think this would be the easiest and would not require exact timing.

user20245: The RaspberryPi is a fairly complete linux computer.  As such it can be a USB Host to many USB Devices.  If you need more serial ports simply buy FTDI equipped USB to serial cables, plug them into a USB hub and plug that into the RaspberryPi.


user3879: There are many different ways of communicating.
In addition to serial you can use a protocol like SPI or I²C. If the Arduino are in close proximity I²C enables many devices to communicate on a common bus.

20429: <p>I wan't to send information from my arduino digital pins to another arduino's digital pins like a string, or a char. Can I do this without something like Software Serial?</p>

<p>The reason I am asking is because I am wanting to send information from several serial devices to my raspberry pi from an arduino. Thing is, that Raspberry pi only has one set of UART pins, so I was thinking because I have extra arduino uno's, why not send then information to the arduino and have it write the received information to the raspberry pi's digital pins..</p>

<p>Now that I am writing this, I think I will connect the 2 arduinos via a serial connection, and use software serial to write out to the raspberry pi, in three different stages, to get the information to the pi.</p>

<p>The reason I am using the PI is I want to display this information on a large screen with many different options, in short the GPU capabilities are what I am using the PI for, that and Processing.</p>

<p><strong>Question still stands though, can you send information over digital pins?</strong></p>
 19409: <p>Yes, you can send information to/from your arduino digital pins using a method called Bit Banging. <a href="https://en.wikipedia.org/wiki/Bit_banging" rel="nofollow noreferrer">Wikipedia</a> (lots more on Google!)</p>

<p>You can use the Arduino to output as an ad hoc serial port or parallel port. The serial could be asynchronous (UART/RS232/I2C) or synchronous (such as SPI). </p>

<p>The down side is you will have to write a fair bit more software to send/interpret the data.</p>

<p>From your description I gather that data is only going one way - from the Arduino to the Pi. I personally would bit bang SPI as I think this would be the easiest and would not require exact timing.</p>
 20245: <p>The RaspberryPi is a fairly complete linux computer.  As such it can be a USB Host to many USB Devices.  If you need more serial ports simply buy <a href="https://www.adafruit.com/products/954" rel="nofollow noreferrer">FTDI equipped USB to serial cables</a>, plug them into a USB hub and plug that into the RaspberryPi.
<a href="https://i.stack.imgur.com/ykCtt.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ykCtt.jpg" alt="enter image description here"></a></p>
 3879: <p>There are many different ways of communicating.</p>

<p>In addition to serial you can use a protocol like SPI or I²C. If the Arduino are in close proximity I²C enables many devices to communicate on a common bus.</p>
