MiSTer FPGA guide: what it is and how to build one

What is the MiSTer?

Let's say that the MiSTer is, in theory, the "summary" of the best emulation can offer today; I say theoretically because it all depends on the knowledge of the real hardware that it is going to emulate. But let's go into a little more detail.

FPGA stands for field-programmable gate array, a type of integrated circuit that can be reconfigured after manufacturing.
Unlike a traditional computer chip, FPGAs use programmable logic blocks and interconnects that can be reconfigured to suit a variety of different purposes. Basically, an FPGA can be reprogrammed over and over to act like any type of digital circuit. While older FPGAs used circuit diagrams, new ones instead use text-based programming to describe the behavior.

This of course is only possible if you know in depth how the chip works at the hardware level, which lately is becoming very detailed especially for proprietary chips thanks to the great work of decapping and subsequent analysis and circuit reconstructions starting from the microscope photographs that some devs (such as the French Furrtek) are carrying out. Once the scheme is understood, this is translated into HDL (Hardware Description Language), which in the MiSTer becomes a “core”, thus allowing the FPGA to emulate as if it were the real hardware.

In this way, if the reproduction of the chip is correct at 100%, you will have a very close proximity to the real machine since the emulation this time is carried out at a "lower" level, the hardware one, thus allowing the various components of the original motherboard emulated in parallel (so we will also have the same bugs present in the original machines!) without any slowdowns, lags or other intrinsic problems of the software emulators which by definition must somehow obviate the impossibility of making the software work in parallel. .

WE PROGRAM THE DE10-nano

This little gem represents the (expensive!) Heart of the device! Unfortunately, it is only possible to use this tab to have all the available functions created by the developer community.

By purchasing the development kit (which is discounted for about 25-30% if you prove to be university students or professors!) You will be ready to install data on microSD and configure the device even in the absence of accessories!

TOOLS REQUIRED

Win32 Disk Imager or any other tool capable of "spreading" the image of an SD (whale Etcher, dd, etc.)
microSD card (the original one from the DE10-Nano is fine too) with a capacity of at least 4GB
The latest version of Mr. Fusion's SD image downloadable from here: https://github.com/MiSTer-devel/mr-fusion/releases
A USB HUB
A USB keyboard

PROCEDURE

Fortunately, over time the system to start the MiSTer firmware for the first time has become very simple! First of all, make sure that the dip switches and toggle switches are set on the de10-nano board as follows:

After that:
Back up the microSD supplied with the de10-nano using Win32 Disk Imager (not necessary but it contains the original software / firmware and it is always good to have a copy even if it is useless for the MiSTer)

2) Extract and flash the latest version of Mr. Fusion's SD image into the microSD
3) insert the microSD into the de10-nano and start it
4) after a few seconds the orange LED will turn on and, if you have also connected the HDMI cable, a blue screen will appear on the screen followed by a splash screen:

Mr Fusion will resize the partitions making all the available space available and copy all the necessary files to the MiSTer. The procedure should not exceed 90-120 seconds, after which the MiSTer menu will appear!

5) Now connect the USB keyboard, go to “Scripts” (if you can’t see the menu, press F12 to bring it up) and confirm the risk warning that appears;

6a) If you have a USB WiFi dongle, choose the script called “wifi” to configure your network (not needed if you have a LAN cable);
6b) Now go to “Scripts” -> Yes -> downloader to start the procedure; you will see a huge number of files being downloaded, verified and installed, and this could take as long as 25-30 minutes!
If everything is configured correctly, at the end the system will reboot, the menu will appear and you’ll have new, updated cores as well as an updated menu and MiSTer main executable (along with loads of new scripts available):

7) Now download from here the update_all.sh script and copy it into the \scripts folder on the internal microSD; put the microSD back into the MiSTer and run it; you’ll be asked whether to carry on running the script (DOWN button) or change the settings (UP button): so press UP; at this point you’ll be offered a series of options to enable/disable; for convenience, set them as follows and start the whole thing:

The system will reboot and you will have everything updated, complete with ROMs for the arcade cores; for the other systems you will have to find them yourselves.

COMPONENTS TO BUILD IT

(necessary and not)

Necessary:
Terasic DE-10 Nano FPGA board Development Kit (includes power supply, mini cable and 8GB microUSB + microSD)

Optional:
I / O Board: useful for VGA / RGB output and keys
USB Hub: Very useful for connecting various peripherals
SDRAM: needed to run several cores
RTC: keep date and time

MiSTer SDRAM Extra Slim Board (from 32 to 128MB as needed):
Here to see which cores consoles require it, here for computer cores.
Dedicated 7-port USB Hub card (if you already have a self-powered one you can use the one on the microUSB port)
MicroUSB adapter to also power the 7-port USB card (if you don't use it, you won't need it)
I / O card with VGA video output, audio, 3 keys, 3 status LEDs, additional microSD slot (in addition to the one already present in the de10-nano), power port similar to USB 3.0 (but not usable as USB) and fan connector.
Fan (if not included in the I / O board)
RTC card (not needed if using a network connection)
Power splitter cable (to power the I / O board and the DE-10 at the same time)
HDMI cable
USB keyboard
WIFI key (optional, you can safely use a network cable as an alternative - it also works as an RTC if connected to the internet)
Bluetooth adapter (required if you want a wireless controller, here a list with the various latencies found - the USB controllers also work very well but the device is small and rather light so you risk doing damage by connecting a controller with the wire)

As you can see the parts needed to build it yourself are different and this is the only way to avoid paying too much! Before the shortage of microchips due to covid19, it was possible to buy pre-built and already programmed for about € 300-350, now with this amount we are now able to do it on our own.

We have to spend from 180 € to 210 € for the de10-nano (on the official Terasic website) and another 85-90 € for accessories (taking them very carefully on AliExpress).

Some of you will say that it is an absurd figure and in part I agree it is also true that for a "one-off" expense you have almost all the machines available (even old computers and numerous arcades!) At your fingertips!

If you want to read more information regarding the operation of real machines and their relationship with the world of emulation you can read this article and the intro of this other article.

How many gigs do you need? Take a look at this article.

Useful keys

F1 - change the background cyclically with the predefined modes (static, wallpaper, color bars, black).

F9 - Start the Linux shell (login: pwd = root: 1 - F12 to return to the menu).

F11 - Bluetooth pairing menu.

F12 - Press it to go from the main menu to the cores menu

Left Ctrl + Left Alt + Right Alt - it corresponds to pressing the "USER" key on the I / O board which usually resets the core where you are.

Left Shift + Left Ctrl + Left Alt + Right Alt - perform a quick reboot of the MiSTer.

Windows + Left Shift + Print Screen – Saves a screenshot (the screenshot files created are saved in a \screenshot folder on the FAT partition of the SD card); this folder will therefore contain subfolders named after the core in which each screenshot was taken; the save format is PNG.

Main icons

This indicates the presence of the LAN connection.

If you have WiFi this icon will appear.

This control panel indicates the presence of a Bluetooth device

The presence (or not) of the SDRAM module is indicated as follows:

No modules installed

32MB of memory installed

64MB of memory installed

128MB of memory installed

TIPS

From what we have seen, the MiSTer finds ROMs by itself based on the file extensions; in any case, it is good to have an organised structure, and the basic one (on the internal microSD) is to have the folder:
root: \ games \
inside which we have the specific folders for each core and that is root: \ games \ SystemName \
as in the picture below:

inside which to insert the respective ROMs (the arcade ROMs go in the root folder: \ games \ mame or root: \ games \ hbmame).
So you can recreate this structure either on a USB device, copy the files, insert the key, turn on the MiSTer, load the core and load the ROMs from its menu!

CONFIGURE A BLUETOOTH JOYPAD

USB pads work as soon as they are connected; for the bluetooth ones it is necessary to have a USB dongle that allows it to work. I used the ASUS model USB-BT21 (the same one used to perform the softmod on the Wii Mini !) and it worked great. You can read the very extensive list of tested products with relative latency times and rankings here.

The procedure is basically the same for almost all devices, namely:

– Go to “Scripts”, Yes, bluetooth_pair; within 60 seconds press the button (or button combination) on the pad that puts it into pairing mode (e.g. for the PS4 pad the buttons to press are PS + SHARE until it is recognised by the MiSTer).

For some joypads the procedure is specific as for example for the PS3:

1 – Connect the pad to the MiSTer via USB.
2 – Press the PS button and wait for the red LEDs to stop flashing (just a few seconds) until only one stays lit.
3 – Disconnect the pad – the lights will start flashing again until it connects, and then only 1 LED will stay lit.
4 – Once the pad is connected, go to the menu with F12, option “Define joystick buttons”, where you can map all the buttons (you will also be asked to map the “buttons” for movement, mouse click and the key to bring up the system menu).

START A CORE AND ITS GAME

To start the games you must first start a specific core from the special selection menu that appears as soon as you start the MiSTer (divided into Arcade, Computers, Consoles, Others, etc.).

Once the core has been started from the menu, use the first item “Load…” to choose the ROM (if the menu does not appear automatically, press F12 or the relative key of the pad you have configured). Before loading it you can fiddle with the various settings available (audio, video, cheats, etc.). Remember that ONLY the games of the loaded system can be started (eg if you start the Genesis core, forget about being able to start NES titles from here).

To exit the core and select another one, go to the screen that is all the way to the right in the menu and use the "Core" item.

To reboot the system: still from the menu screen located all the way to the right, select the last option “Reboot (hold cold reboot)”; alternatively you can press on the keyboard, if it is still connected, the Left Shift + Left Ctrl + Left Alt + Right Alt combo; this “warm” reboot will take approximately 2 seconds. By keeping pressed for a few seconds on the item “Reboot (hold cold reboot)” the system will restart completely and it will take about 7 seconds.

IT IS NOT POSSIBLE TO TURN OFF THE DEVICE, to do this you must turn off the power in the way you prefer!

HOW TO ASSEMBLE THE MiSTer FPGA!

Let's start with these components by saying that there will be NO welding to be done:
As you can see the USB expansion card, compared to the one shown above, has 9 ports instead of 7;
1 of these [PWR1], is used for the power supply;
in the kit shown in the photo the splitter cable is also different as it has a barrel jack and a USB (instead of 2 barrel jacks like the one in the photo above);
this is due to the fact that there are different versions of these USB expansion cards, choose the one you like best and, if you take it apart, make sure you also buy the splitter cable and the corresponding USB connector to pass the data (see beyond).

We screw the fan to the I / O board with the 4 screws and connect its connector.

We unscrew the plexiglass “lid” of the de10-nano and put it away (like in its original box so as not to lose it) while we keep the 4 silver screws and the gold supports aside because we will need them.

We reassemble, by screwing them, the golden supports on the USB board (which will become the base of our MiSTer).

From the box of the de10-nano we recover the rubber foot covers and apply them as in the photo (they will serve to prevent the finished structure from sliding on any smooth surfaces).

We connect the double microUSB connector to the de10-nano and to the USB card (this connector will be used to pass the data, it will NOT be used to power the card!). This connector, as already mentioned, can be made differently depending on how the USB expansion card is built.

From the accessory kit we screw the 4 additional supports (spacers).

If you have purchased it, this is the time to connect the RTC card (and maybe even insert the CR1220 battery); attention, the plastic that limits the connector of the de10-nano where the RTC is inserted is very delicate (luckily the pins are solid)!

Now we place the “roof” of our tower represented by the I / O board.

Let's fix it with the 4 silver screws we had set aside at the beginning.

Finally, connect the SDRAM module as shown in the photo (the writing goes outwards as the text itself says).

Now let's connect the power splitter correctly: the male USB connector goes into the USB female called PWR or POWER of the card with the 9 USB ports (the one shown in the picture) while the barrel jack goes into the usual female connector of the de10-nano. The remaining female jack should be connected to the original power supply (or other power supply of your choice for the de10-nano). This cable, as already explained, can be different depending on how the USB card is made.

YOUR MiSTer IS FINALLY READY !!!!

Do we want a case for our MiSTer?

Let’s start by saying that the case is usually supplied with a pre-built MiSTer but, if needed, we can make one ourselves. The whole problem lies in the version of the USB hub we are going to use; in fact, the cases currently available to buy separately are designed for an earlier hub revision than the latest one currently available (which is 2.1, the one you can see in the article), so the layout of the side holes may not match.

We at retrofixer have developed one with our logo that fits perfectly (well, almost!) the USB hub revision 2.1 together with the I/O board revision 6.1 (the same one described in this article):

For this case we used this base with a few modifications to the holes, and the final assembly differs from the one described earlier in the use of the spacers joining the 3 boards together. In fact we used the standoffs and matching screws you can see alongside. They are available in both plastic and brass; what matters is that the size is M3 and that the lengths in millimetres match those in the image.

The final result is shown alongside.

Which, fully “exploded” (that is, with the case plates already fitted), looks like the one alongside.

For a final result like this.

Now, the only modification left to do is to space out the 2 male USB connectors that carry data between the de10-nano and the USB hub; to do this you have to desolder the connector that plugs into the de10-nano’s microUSB port and resolder it onto the pads already present slightly higher up on its small PCB (yes, this little gadget was evidently designed with this solution in mind too). In the picture you can see the difference in spacing between the 2 versions:

FAQ

SDRAM yes or SDRAM no?
There most cores DOES NOT require SDRAM expansion.
32MB they are required by some GBA titles (but not necessary as the MiSTer can take the missing MBs from the DDR3 of the de-10 nano but with the potential detriment of the emulative yield which is the purpose of the MiSTer so we might as well take the module with more than 32MB) while 128MB are required by some Neo Geo titles. 64MB it is a possible configuration but little used.

Missing the BIOS?
Go here, download the “update_all.sh” script, copy it into the scripts folder on the microSD and run it; on start-up you will be asked whether to continue with the update or configure the script: configure it and make sure the BIOS option is “enabled”!

Is it a mess to find MAME and HBMAME ROMs?
Here the scripts that do for you! It is mandatory to have already installed the .mra cores of the titles / arcade platforms you want (eg cps1 / cps2) because the scripts analyze those to go and fish the related game data.

Did someone say WALLPAPERS?

If you want beautiful wallpaper in the background download and run the files of this script; it will download for you some fantastic images that you will see change at each (even quick) reset of the MiSTer; to do this, once started, press F1 until you see the first wallpaper; at this point at each restart the wallpaper will change (DO NOT try to scroll through them by pressing F1, it will not work!).

Space problems?

The .zip format is used by several cores but check the cluster size of the formatting you use in the USB memory device: if the size is "large" and you have many files LESS than the size of the cluster (eg a lot of material for C64) then it is NOT CONVENIENT to zip; in some cases the zipped format does not work as for example with CD images; for the latter several cores (eg PSX, SegaCD, PC Engine CD) support the CHD format of MAME which you can find in its huge SoftwareList!

Hints on using cheats?

The cheats files are located in the \ cheats folder and are divided into folders bearing the name of the system and within these we have zipped files that MUST have the same name as the ROM in which we want to use them; ex.

\ cheats \ NES \ Mario.zip` for the game "Mario.nes"

If you use files in image format (ISO, CHD, etc.) the .zip file MUST reside in the folder where the disc image is present.

What is the SOG OVR AUTO switch on the I / O board for?

SOG = Sync on Green - This switch controls whether sync signals are placed within the green color channel (some older CRTs used sync-on-green). If set to Auto, the core decides whether to use it, but you can force the setting by setting it to OVR.

In some cases, using a cathode ray tube monitor output, the image may be "greenish":

in this case they recommend removing C6 below the switch in question:

with the following result:

Do you recommend any peripherals in particular?
Let's say that to keep everything rather compact and not very "protruding" it would be a good thing to opt for very small USB peripherals. Below are those tested and working without having to install anything; from left to right we have:

WiFi MODULE - HomeSpot 150Mbps Wireless N WiFi USB Nano Adapter [VID: PID = 0BDA: 8176 = Realtek RTL8188CU]
USD READER - Realtek Card Reader [VID: PID = 0BDA: 0136]
BLUETOOTH MODULE - ASUS USB-BT21 [VID: PID = 0B05: 1715]

Note in particular how the uSD reader is built in such a way as to insert the card from the opposite side of the "hole" for the female USB connector, limiting the space occupied to a minimum:

Finally, remember that Bluetooth peripherals have well-defined operating specifications, so check which Bluetooth version is required for the device (e.g. controller) you want to connect, and make sure the Bluetooth dongle connected to the MiSTer matches. For example, to get the Switch controller recognised you need a version 3.0 dongle, for a Stadia controller you need a version 4.2 Bluetooth dongle, while the Luna controller needs Bluetooth 5.0.

Below is a tested, working model that supports both 2.4/5GHz WiFi and Bluetooth 5.0 in a single dongle:

Realtek [VID:PID = 0BDA:C820]

The HDMI cable partially powers the MiSTer! How can I solve?

If you too, connecting the MiSTer to an external monitor through the HDMI port, have noticed that, even if disconnected from the power supply, the I / O board is partially powered (some LEDs light up, the fan starts to spin, etc. does not start) the problem seems to be in the operation of the CEC (PIN 13 of the HDMI connector); fortunately this “quirk” doesn’t happen with every HDMI monitor, but to be sure it doesn’t happen you have to test it “in the field”. This “spurious” power seems to cause SDRAM malfunctions, so if you run into the problem it’s advisable to fix it. One solution is to cut a small trace on the I/O board, near the U34 IC, highlighted in the image:

Since cutting is not very nice, though, and we love more “elegant” solutions, we chose an adapter that disconnects that pin simply by sitting between the cable and the HDMI socket ON THE MONITOR (NOT on the MiSTer!!). If you look for it online it has names such as “NO CEC HDMI / NON CEC / MINUS CEC”. The one we used successfully in our tests is this one:

What if you don't want to use the HDMI output?

The MiSTer has several “juicy” options that you can use; first of all it allows a simultaneous output in both HDMI and VGA:

but in order to use the VGA port correctly, depending on the monitor to be used (CRT, dated LCD, recent LCD, etc.) and depending on the output signal there are some hardware settings and parameters contained in the MiSTer.ini file ( which must be inserted in the root of the system microSD) to consider:

– VGA ->VGA

If it does not work directly without changing anything (black screen or errors on the screen such as "out of range" or "out of range") set the following parameter in MiSTEer.ini:

vga_scaler = 1

NOTE: when the vga_scaler parameter is set to 0, the VGA port of the I / O board outputs the original 240p signal for most cores, the old standard for 15khz televisions. Many LCD monitors may not recognize it because it is below the minimum standard of VGA on CRT (480p / 31khz); for this reason, if the signal is not shown with VGA connection, the vga_scaler parameter must be set to 1, so as to have an output like that of the HDMI port (720p if used in conjunction with the video_mode = 0 parameter).

if still not, set it SOG switch on OVR (therefore not on "AUTO"):

if it still doesn't go jumper the pins for the 5V near the VGA connector:

if your I / O board only has holes at that point and doesn't have pins, you have to solder them.

If it still does not work as a last attempt, substitute the value for the "video_mode = 0" parameter:

video_mode = 1680,104,176,280,1050,3,6,30,146250

– VGA->

RCA (or S-Video)

To use this mode (probably useless to most people if not nostalgic of the composite) you will need a card that converts the signal type this:

and you will have to set the following things to avoid having a black screen:

in hardware settings:

jumper the pins for the 5V in the I / O tab (see above)

Disable the SOG (may not be necessary)

in MiSTer.ini:

composite_sync = 1

vga_scaler = 0

Do you recommend any monitors in particular?
Recently, thanks to a tip from Bisboch, I stumbled upon a beautiful refurbished Retina LCD display directly embedded within a frame:

As you can see it is available in 2 versions: with VGA, 1 HDMI and without microUSB or with 2 miniHDMI without VGA but with a very convenient microUSB port from which it can be directly powered !!!

The product specifications (which you can therefore also make yourself):
– LCD LG LP097QX1 (or SAMSUNG LTN097QL01) – 9.7″ – 2048X1536 – QXGA (4:3) 264PPI – 3 megapixels [both models appear to be identical in specification despite the different manufacturers]
- Driver board: VS-RTD09703-V1 (or at least so far this has been found inside so there is no guarantee that they will not change boards over time!)
- Thickness of the 2 versions: 13mm (model without VGA) and 22mm (model with VGA)
(possibility to add an external panel to make it also touchscreen)

The wonderful thing is that, by choosing the version with the possibility of powering via microUSB and with a power bank that delivers at least 3A, you can power both the MiSTer (basic requires about 1.3A) and the display (which consumes about 1.04A):

making everything absolutely "portable"!

The display is also equipped with 2 speakers inside:

In the dedicated thread recommend to combine it with a well-made miniHDMI cable, the one supplied may not reach the maximum resolution described in the specifications of the LCD panel.

Link to product: https://it.aliexpress.com/item/1005001689746001.html

Can I change resolution without editing the Mister.ini file?

Yes, using the script called “ini settings”: under “video_mode” (usually the first entry) you can change resolution without having to remove the microSD card.

Miscellaneous / Backup

If you want to go back to the original MiSTer SD as provided by Terasic, here is a dump of the original microSD

The image (.img) has been compressed in rar.
You can download it for free 7-Zip to open this format too, while for writing to the SD you can use Whale Etcher