An SD-card image of a RetroPie installation was recently made available. This post describes the individual steps taken in order to create such an image. While it serves me to ensure that no steps are forgotten during future updates, this post provides also an insight into the individual steps for people with interest in this topic.

As always, you are invited to make suggestions or comments to further improve the RetroPie Image! Especially the set of packages to be removed can still be optimized I think.

And here it is, the step-by-step recipe for creating the RetroPie Image:

1. Download and copy the Raspbian image on SD card
2. The raspi-config script automatically starts on first boot. From here, expand the root file system
3. Then reboot
4. Login as user “pi” and run

   sudo apt-get update
   sudo apt-get install -y git dialog

5. Fetch the latest version of the RetroPie Setup Script with

   cd
   git clone git://github.com/petrockblog/RetroPie-Setup

6. Start the RetroPie Script

   cd RetroPie-Setup
   sudo ./retropie_setup.sh

7. Select “binaries-based installation” in RetroPie Script and press ENTER
8. Check message dialogs at the end of binaries-based installation.
9. Select “Setup” in RetroPie Script and press ENTER
10. Set EmulationStation to start on boot.
11. Set SNESDev to start on boot and to poll the button and game pads. (There are reports that game pad configurations override keyboard settings, so that the settings for game pads are not set as default anymore. If you want to use a joystick or game pad, you have to manually configure it.)
12. Enable splashscreen on boot.
13. Install and configure SAMBA.
14. Install USB-ROM-Copy service.
15. Install GPIO gamepad drivers (added 04.05.2013)
16. Exit the RetroPie Setup Script and run

    sudo raspi-config

17. Set overclock to preset ‘Medium’The following steps are only needed, if you want to create an SD card image yourself. I post them here to make the generation of the RetroPie image more transparent:
18. Reboot
19. Configure EmulationStation game pad input
20. Testing of all emulators with at least one ROM
21. Exit Emulation Station
22. Remove unnecessary packages via

    cd
    chmod +x ./RetroPie-Setup/tools/prepareSDCardimage.sh
    sudo ./RetroPie-Setup/tools/prepareSDCardimage.sh

23. Please note that the dd command, which is also used in the following, is a very powerful command that is able to break your system! If you are unsure about it, you can have a look at this article, that explains its use for RPi SD card handling. But now the explanation of the next step:
    Shutdown the RPi, use another computer to create an SD-card image, e.g., with

    dd if=/dev/disk3 bs=2m of=RetroPieImage_verX.img

24. Compress the image into ZIP format with

    zip -9 RetroPieImage_verX.zip RetroPieImage_verX.img

25. Create SHA1 checksum with

    shasum RetroPieImage_verX.zip

26. (Upload the image.)

And that’s it.

Why might this SD-card image be of interest for you?
Doing a manual installation with the RetroPie Setup Script is a better way for learning what actually gets installed. Also, you might already have installed something else that you do not want to re-install and configure again. Another cause for manually installing everything with the RetroPie script is that you can configure which components get installed and which not. However, if you are already familiar with the RetroPie Project, the setup script and the components it installs, or if you just would like to quickly turn your RPi into a retro console this SD-card image might definitely be useful for you!

The image was tested on an Raspberry Pi model B, revision 1 (256 MB). It is a ready-to-go installation that just needs to be filled up by your ROMs and, eventually, your BIOS files. SNESDev is also running so that controllers that are attached to the RPi, e.g., via the RetroPie GPIO Adapter, can instantly be used.

The SD-card image comes with themes for Emulation Station thanks to Xevin, Aloshi, and others around Emulation Station. I am pretty sure, though, that many people would come up with quite different design and I invite you to submit your ideas

This is version 1 of the RetroPie Image and there is room for a lot of improvement! You are invited to contribute in any way, let it be themes, configuration, setup updated/comments etc. etc. !!!

You can get the image in the RetroPie Downloads section.

Update: A detailed description about the steps for creating the image was posted here.

I hope that all resources, links, pages, etc. are working – please tell me, if you find something that is not working!

If you have any comments or suggestions, tell me!

The video shows the RetroPie GPIO adapter connected with two SNES controllers within a PetRockBlock PIE case. The current Raspbian distribution is running in the video with a RetroPie Setup Script installation. The controllers are polled by the gamecon GPIO module that can be installed with the setup script. The button is polled with SNESDev, which is also configured with the setup script.

The RetroPie GPIO adapter

Based on the experiences with a previously presented adapter PCB I designed a new SNES adapter PCB specifically for the use with the Raspberry Pi.

Hardware

This GPIO adapter aims at

• an easy and practical installation
• as well as providing circuitry protection
• and a button that can be used arbitrarily by software.

An easy and practical installation of the adapter board is achieved by using a 2×13 pins female header for a connection to the GPIO pins and 2×5 pins male header for the connection to, for example, (S)NES controller sockets. The only tinkering needed for a connection to (S)NES connectors is the soldering of the ribbon cable to the connectors. The size of the adapter PCB is only 0.91 in x 1.32 in (23 mm x 33.5 mm). This size does not increase the needed overall volume of the Pi much and allows the usage of most existing cases.

For a practical application the adapter is provided with a circuitry protection as it was proposed in a thread of the official Raspberry Pi forum. To handle over currents a resettable fuse is put on the supply rail. Possible transients are taken care for by a buffer IC 74HC125. As stated by RPi wiki site about circuitry protection

these ICs provide an in-line connection which is buffered via an internal transistor switch to isolate the input from the output.

Four GPIO pins, which would correspond to two data lines, the clock, and the latch in case of (S)NES controllers, are buffered by the adapter.

A momentary on push button is also part of the adapter board. The button is also connected to one of the GPIO pins and, thus, the status of the button can be polled with any suitable software. This allows, for example, to add a reset/back button that is needed with a keyboard-less setup and controllers with no redundant buttons like the SNES or NES controllers.

Pin Out

GPIO pin out: The pin out of the board to the female 2×13 pins header is matched to the gamecon GPIO driver that can also be installed and configured from within the RetroPie Setup Script. The exact pin out together with the according pins on the SNES connector are listed in the following and shown in the diagram (for revision 1 of the Raspberry Board):

• VCC (3.3V): pin 1
• Ground: pin 6
• Clock: pin 19 (out)
• Button: pin 11 (in)
• Latch: pin 23 (out)
• Data 1: pin 7 (in)
• Data 2: pin 5 (in)

Connectors pin out for (S)NES connectors: The (S)NES connectors are soldered to a 10-wire ribbon cable that has a 2×5 pins female ribbon crimp connector at the other end. The pin out together with the according pins on the SNES connector are shown in the diagram:

Here is an image of two SNES connectors soldered to the ten-wire ribbon cable and connected to the adapter board:

For those of you that are interested in the components details, here are the manufacturer part  numbers:

• Tri-state buffer: SGS-Thompson Microelectronics M74HC125M1R
• PTC resettable fuse: ESKA LP60-010
• Momentary switch: APEM PHAP3305D
  

Schematics and assembly Guide: You can find the schematics of the RetroPie GPIO Adapter here

RetroPie GPIO Adapter Schematics

Download 55.08 KB 798 downloads

RetroPie GPIO Adapter Assembly Guide

Download 256.31 KB 769 downloads

Additional GPIOs: It can also be seen from the schematics that revision 1.1 of the adapter breaks out four additional GPIO pins (GPIO pins 0, 14, 21, 22) together with ground and the 3.3V pin. This provides the possibility to attach additional hardware to the GPIO and use the RetroPie GPIO adapter at the same time. Note, however, that these additional pins do not provide any circuitry protection.

The dimensions of this adapter matches the ones of the PetRockBlock PIE case. This means that  both can be combined with each other to build a keyboardless gaming console with the RPi at its center.

Software

In order to use the RetroPie GPIO adapter a driver is needed that reads the states of the controllers and the button and maps these to the input system of the operating system. This can either be done in kernel- or in user-space. The SNESDev software is an example of an user-space application that interfaces with the controllers. The mentioned gamecon driver is an example that runs in the kernel-space. I have modified the sources of SNESDev such that it can be used with the RetroPie adapter.

With respect to the slightly changed GPIO pin out of revision 2 of the Raspberry, the software has to be matched to the actual revision of each board. In the recent version of the RetroPie Setup Script, the installation and update routines for the gamecon GPIO driver automatically determine the board revision and adapt the configuration of the driver accordingly. Many thanks go to “Marqs” for this!

During the design of the board I was not aware of the “safe mode” of the Raspberry Pi: Adding a jumper between pins 5 and 6 of P1 results in /boot/config.txt being ignored (except for avoid_safe_mode) and a default cmdline.txt is applied, followed by loading kernel_emergency.img. As stated in the official forum

if you connect external hardware to that pin, the worst that will happen is it falsely triggers safe mode.

To avoid this safe mode when the adapter is attached a setting has to be made in /boot/config.txt. This could be done, for example, by opening the config.txt with

sudo nano /boot/config.txt

adding

avoid_safe_mode=1

and saving the changes with “Ctrl-X”, which has to be confirmed with “Y”.

Demo video

A video of the adapter in action can be found in this post.

Installation and Troubleshooting

First of all make sure that you do not have any short bridges or any other possibly problematic parts you soldered. A multimeter could be very handy here. Also, check, if you soldered the tri-state buffer with the correct orientation on the PCB. As stated in the assembly guide: “Pin 1 must be directed towards the fuse holes.”

The software part: Make sure that you are using the latest revision of the sources. If you are going to use the gamecon driver for polling the game pads (which I also prefer, because it is more resource efficient) you need to use the “poll only the button” option for SNESDev. Otherwise the gamecon driver and SNESDev might interfere and lead to some strange behavior.

With the gamecon driver enabled you can test for working connections between the game pads and the RPi with the jstest command (Ctrl+C exits the tool):

jstest /dev/input/js0

and

jstest /dev/input/js1

will test the first and the second game pad.

If you are using SNESDev for polling the game pads you need to use the option “poll game pads and button” in the menu of the RetroPie Script. If everything ism assembled and set up correctly button presses on the game pads will act as keyboard input and you will see according outputs on the console.

A long press (more than 1 second) on the button will lead to a key press of “r” which, again, can be checked on the console.

Conclusion & Getting it

The RetroPie GPIO adapter allows an easy and practical connection of NES and SNES controllers via the GPIO pins of the Raspberry Pi. The size of the adapter is kept as small as possible and should fit into most existing cases. It contains circuitry protection against over currents and transients. Furthermore, a momentary push button is installed on the adapter that can be used, for example, as a back or reset button. The pin out of the GPIO male header is matched to the already existing gamecon RPi GPIO driver, which can easily be installed and updated with the RetroPie Setup script.

I have some of the RetroPie GPIO adapters on hand. If you would like to buy one (only the components and the board for self-assembly or fully assembled and tested) please have a look here. Besides the adapter itself, it comes together with a ribbon cable (about 10 cm long) and a ribbon crimp connector.

It has been some weeks ago since my last post, but things regarding the Raspberry Pi and the idea of the universal console did not stand still. Actually, there has been a lot of progress in many aspects of (what I will call from now on) the “RetroPie Project“.

I prepared a logo for that as shown on top of this post. What do you think?

What is achieved in the meantime

In a previous post, I have pointed out several aspects that have (at least) to be considered for turning the Raspberry into a retro-gaming machine. Several people actively work on solutions for the individual aspects and, currently, there is a lot of drive in the development. Te vivid usage of the official forum is an essential part of that. Let me give you a brief overview about what has happened within the last few weeks:

• Emulation Station: In order to browse and run your game collections on the Raspberry Emulation Station provides a graphical front-end that is specifically designed for the Raspberry Pi platform. Comments, suggestions, or bug reports are welcome and constructively discussed for the further development of the front end.
• Emulators: A wide variety of emulators that are running on the Raspberry exists in the meantime and people are still working on additional emulator ports or exploring which emulators are running on the RPi. Currently, emulators for 18 systems can be installed with the RetroPie Setup script.
• Raspberry Pi Firmware: The official firmware of the Raspberry Pi is constantly developing. Among others, outstanding updates in the last weeks were the improvements with the analog audio output and the introduction of the “turbo mode” without voiding the guaranty.
• RetroPie Setup Script: RetroPie Setup Script intends to ease the installation of various emulators as well as the configuration and setup of controllers, drivers, and the front-end. With the feedback from this blog and the thread in the official forum the script is permanently enhanced.
• Gaming case with slots for SNES connectors: The acrylic case that I wrote about has proved to be useful and robust in practice. I will revise the design of the case to account for the RetroPie GPIO adapter that I will present soon.
• (S)NES-controller GPIO adapter: The PCBs of the revised version of the SNES-controller GPIO adapter board have recently arrived! I will post an article about it in the next days. Let me just tell me for now that they are great!
• Gamecon driver for GPIO interface: A gamecon driver has become part of the RetroPie Setup script and provides the possibility to use the GPIO pins for connecting various Nintendo controllers. The GPIO adapter board mentioned above can be used with this driver out-of-the-box. The latest version of the driver makes use of Dynamic Kernel Module Support (DKMS) which “enables kernel device drivers to be automatically rebuilt when a new kernel is installed” [Wikipedia].

To everyone involved in this so far I have to say “well done and thank you for all the work and what was achieved in the meantime”!

Open issues

There are still open issues:

• Better Sound Quality: The ALSA drivers are still leading to cracking noise when running a RetroArch based emulation core. Even though the use of SDL audio drivers leads to good improvements a more stable implementation of the ALSA drivers would decrease the computational load and, thus, increase the performance of the emulator.
• Controller configuration: Currently, most of the configuration of gamepads and joysticks has to be done from the command line and can be a challenge.
• Keyboard-less setup: If the Raspberry should be used as a dedicated console the interface must be controllable without a keyboard. Since the RPi does not have an on-off button or a reset switch or any other programmable buttons, this can only be solved by adding additional hardware. The GPIO adapter that I mentioned above will solve this problem and allow for a keyboard-less setup. Right now, however, SNESDev and/or the gamecon driver still need to be adapted for that piece of hardware.
• Improved Stability: The ongoing enhancement of the various components leads to instabilities from time to time. As long as there is an active development I am sure that the overall stability will reach a point where the system is experienced to work reliable in (gaming-)practice.
• Themes for all systems: Currently, not all systems that can be installed by the RetroPie Script have a theme for Emulation Station. There is, however, ongoing work and any suggestions or help is appreciated.
• RetroPie image: Having a working image with a ready-to-go installation that people can simply download and copy to their SD card would significantly simplify things for many people. This will become a hot topic as soon as the individual components of the system (firmware, front-end, scraper(s), emulators, drivers etc.) are mature enough.

This concludes my brief interim report about the RetroPie Project. Thank you again to everyone who has contributed to this so far! Everyone who has not yet put his hands on this, but has interest I would like to encourage to have a look and to contribute in whatever way!

As always, if you have any comments, suggestions, or questions feel free to get in contact with me.

If you want to use original NES or SNES controllers with your Raspberry Pi, you could use SNESDev, which I have written about some weeks ago. SNESDev makes use of the user-space input module and simulates a virtual keyboard. This means that button presses on the controllers are mapped to key presses on the Raspberry. Another approach for interfacing a controller with the Raspberry from the software side is to use a specific Linux input driver. Marqs has adapted such a driver to the Raspberry Pi hardware and made it available to the public.

Compared to SNESDev using that driver has the advantage that the whole device handling is done in kernel space. This decreases the performance overhead and allows for lower latencies. The SNES adapter board can be used in combination with this driver. I used this wiring:

These are images of the adapter board soldered to the connectors and the the ribbon cable connector ready for assembly:

Besides the source code Marqs provides a pre-compiled module for firmware 3.1.9+. He generously allows to provide a zipped archive for download at the Github site of the RetroPie Setup. You can either use the RetroPie setup script for installing the driver automatically or manually put everything in place. The README that is contained in the download explains the necessary steps for that. Note that root privileges are needed to follow these steps:

For future firmware version the module needs to be re-compiled (at least as long as it is not part of the official Raspbian kernel tree). This involves compiling the kernel sources on your own and takes some time. Marqs puts it like this: “Basically you have to download kernel sources and copy the driver and configs to the kernel tree. Then you’ll need to rebuild the kernel after selecting the module in menuconfig (see http://elinux.org/RPi_Kernel_Compilation). Once the kernel is built, the module can be rebuilt separately (kernel compile is needed just for creation of Module.symvers).”

So far, the driver is working without any problems for me.

I have created a wiki for the RetroPie setup script. That wiki could serve as a source of all kinds of collected information around the components that are installed with the RetroPie setup script and can be enhanced by all users! You can find the wiki at https://github.com/petrockblog/RetroPie-Setup/wiki. If you find some useful information  in a forum or another blog post or comment that was helpful for you then this might be a good candidate for an entry in the wiki. You are invited to fill the wiki with content!

As a step towards an increased usability I have just committed an update for >>the script<< that implements the generation of a debug log. That log includes all relevant information about files and settings that are important for the RetroPie installation.

I hope that this will be useful in the future …