mini version of the Donut Dongle that enables auto profiles for RS-232 based switches for the RetroTink 4K Pro/CE
- 3DP case now available on MakerWorld
- Compatible with the SVS
- Connect multiple Donut Holes, Donut Dongles, gSerial Enablers simultaneously via a headphone jack splitter.
- Must reflash "firmware" with offset variable set so SVS profile numbers don't overlap.
- Up to 5 have been connected together simultaneously. More may be supported, but this is the max number I've been able to test.
- Full instructions listed below for building your own!
Tip
If DIY is not your thing. I have assembled versions available in my Ko-fi shop.
Note
NEW beta allows:
- MT-VIKI Disconnection Detection - when an input is powered off and on, the profile is resent.
- front case buttons/remote NOW change profiles on the MT-VIKI HDMI switch. Thanks to Arthrimus!
- auto-switching on Extron Matrix switchers that support DSVP. Works with RGBS/HV and HDMI/DVI signal types.
- Support for older Extron Crosspoint (non plus) matrix switchers
For Matrix auto-switching, use the follow Options to enable:
bool automatrixSW1 = true; // set true for auto matrix switching on "SW1" port
bool automatrixSW2 = false; // set true for auto matrix switching on "SW2" port
int amSizeSW1 = 8; // number of input ports for auto matrix switching on SW1. Ex: 8,12,16,32
int amSizeSW2 = 8; // number of input ports for auto matrix switching on SW2. ...
uint8_t ExtronVideoOutputPortSW1 = 1; // For non "Plus" Extron Matrix models, must specify video output port that connects to RT4K
uint8_t ExtronVideoOutputPortSW2 = 1;
uint8_t const vinMatrix[65] = {0, // MATRIX switchers // When auto matrix mode is enabled: (automatrixSW1 / SW2 above)
// set to 1 for the auto switched input to trigger a Preset on SW1
// set to 2 for the auto switched input to trigger a Preset on SW2
// set to 3 for both SW1 & SW2
// set to 0 to disable this feature (default - aka input goes to all outputs unless defined in voutMatrix)
//
// set the following inputs to the desired Preset #
// (by default each input # is set to the same corresponding Preset #)
uint8_t const voutMatrix[66] = {1, // MATRIX switchers // When auto matrix mode is enabled: (automatrixSW1 / SW2 above)
// set to 1 for the auto switched input to go to ALL outputs (default)
// set to 0 to select outputs to be enabled/disabled as listed below
//
// When auto matrix mode is disabled:
// ALL input changes to any/all outputs result in a profile change
// disable specific outputs from triggering profile changes
(current list, but not limited to)
| Switch | Supported | Notes |
|---|---|---|
| TESmart 16x1 HDMI | yes, confirmed first hand | Amazon link for reference |
| TESmart 8x1 HDMI | unconfirmed, but should work, let me know! | |
| MT-VIKI 8 port HDMI | yes, confirmed first hand | Amazon link for reference |
| Extron RGBHV sw6 | yes, confirmed first hand | auto-profiles triggered by manual selection or auto-switching |
| Extron SW4 VGA Ars | yes, confirmed by "Nobody" on the RT4K Discord | auto-profiles triggered by manual selection or auto-switching |
| Extron DXP 88 | yes, confirmed first hand | Auto-switching can be enabled in "Options" section of .ino. Works with Presets. On SW1, Preset 1 is S1_ profile. On SW2, Preset 1 is S101_ profile, etc |
| Extron CrossPoint Plus, MVX, etc | yes, confirmed by other users | Auto-switching can be enabled for switches that supports DSVP and are RGBS/HDMI/DVI signal types. By default, works with Presets as shown in the Note above. |
| Extron CrossPoint E-series | yes, works with Presets and Input changes | Must set ExtronVideoOutputPortSW1 / SW2 variable to output connected to RT4K |
PCBs for this project:
- Donut Hole
- VGA Adapter (VGAPassthrough or YC2VGA)
- (Optional) TESmart_connector
- (Optional) MT-VIKI / Extron / DB9 adapter
There are plenty of options for PCB manufacturing but I prefer JLCPCB (No affiliation). Using the gerber (.zip) files provided, it's easy to place an order. Below are some tips/guidelines:
- 1.6mm Thickness
- For Surface Finish, "HASL(with lead)" is fine
- 4 Layer PCBs are the same cost as 2 Layer for the VGA Adapters. Because of that, the inner 2 layers are being used as ground planes for better EMI protection. Thanks to https://x.com/zaxour for the idea!
- "Remove Mark" option is now free on JLCPCB. Use it!
- All remaining default options should be fine
- Let me know if you have any questions!
| Qty | Designation | Part | Link | Notes |
|---|---|---|---|---|
| 2 | C1,C2 | 0.1 uf / 100nf 50V X7R 0805 Capacitor | Digikey | |
| 3 | C3 - C5 | 0.3 uf / 330nf 50V X7R 0805 Capacitor | Digikey | |
| 2 | R1, R2 | 10K OHM 1% 1/8W 0805 Resistor | Digikey | |
| 1 | U1 | IC BUF NON-INVERT 5.5V SOT23-6 | Digikey or alternate | |
| 1 | U2 | MAX3232 SOP-16 RS-232 Interface IC | AliExpress | |
| 1 | PH1 | PJ-307 3.5mm Stereo Jack | AliExpress | |
| or 1x 3.5mm Audio Jack Socket | AliExpress | Like the PJ-307 but missing the inner 2 poles which arent needed anyways | ||
| 2 | J2 | PJ-320 3.5MM Headphone Jack Audio Video Female | AliExpress | Color: PJ-320B DIP |
| 11 | J3,J4 | 2.54mm male pin headers | break off the male headers that come with the Arduino Nano | |
| 1 | Arduino Nano type c | Support RetroRGB! | Make sure the headers are not soldered. | |
| 1 | Any 3.5mm / aux / stereo / trs / cable | AliExpress | ||
| 1 | usb-c cable for Arduino power & programming | AliExpress | ||
| (needed for RS-232 DB9 connections) | MT-VIKI / Extron / DB9 adapter | DIY | ...or purchase from below | |
| DB9 Male to 3.5mm Male Serial RS232 Cable 6feet | Amazon | "MUST" be wired as so: DB9 Male Pin 5 -> Sleeve, DB9 Male Pin 2 -> Tip, DB9 Male Pin 3 -> Ring |
I recommend the Official Arduino IDE and guide if you're unfamiliar with Arduinos. All .ino files used for programming are listed above. The following Library will also need to be added in order to Compile successfully.
- Libraries:
- <AltSoftSerial.h> Follow these steps to add AltSoftSerial.h
- Goto https://github.com/PaulStoffregen/AltSoftSerial
- Click the GREEN "<> Code" box and "Download ZIP"
- In Arudino IDE; goto "Sketch" -> "Include Library" -> "Add .ZIP Library"
- <AltSoftSerial.h> Follow these steps to add AltSoftSerial.h
Some Arduino Nanos come with an Old Bootloader and won't Upload unless specified. If you get errors when trying to upload, swap to this option as a possible fix.
- 1 - Download and install the Arduino IDE for your PC or Mac
- 2 - Click the green "<> Code" button above and "Download ZIP".
- 3 - Extract the .zip file and open up the "Donut_Hole.ino" file in the Arduino IDE. It will ask if you would like to move this file inside a folder, select OK.
- 4 - With the source code now open, select "Tools" -> "Board" -> "Arduino AVR Boards" -> "Arduino Nano"
- 5 - Connect the Donut Hole device to your PC or Mac using the usb-c cable. You should see an LED light up when connected.
- 6 - With the Donut Hole now connected, select it's "port" by going to "Tools" -> "Port", and select the port that starts with "/dev/cu.usbserial-" (on Mac) or "COM" if on PC.
- 7 - Almost done! :) In the code itself, find the line that starts with "uint16_t const offset = 0;" and change the 0 to 300. It should now look like this: uint16_t const offset = 300;
- This will give you profiles 301 - 399 for SW1 and 401 - 499 for SW2
- At the moment this is line 32
- 8 - From the menu at the top, select "Sketch" -> "Upload". You should see the LEDs on the Donut Hole flicker and a message that says "Done uploading." if successful.
- If you get errors, see the section above about changing the "Bootloader" type.
- 9 - Disconnect the usb-c cable from your computer and give it a whirl! You can repeat these steps in the future to make any other changes or update if a newer firmware is ever released.
-
Make sure "Auto Load SVS" is "On" under the RT4K Profiles menu.
-
The RT4K checks the /profile/SVS subfolder for profiles and need to be named: S<input number>_<user defined>.rt4 For example, SVS input 1 would look for a profile that is named S1_SNES.rt4. If there’s more than one profile that fits the pattern, the first match is used.
-
Check the RT4K Diagnostic Console for Serial commands being received as confirmation.
Input 1-10... = S1_ - S10_ ...,etc
The "offset" option can be used if using multiple Donut Holes, gSerial Enablers, Donut Dongles are connected to the RT4K via a headphone splitter. For example, if using a 2nd, change "offset = 300" for the 2nd device to be SVS profiles 301 - 310.
uint16_t const offset = 0; // Only needed for multiple Donut Holes, gSerial Enablers, Donut Dongles. Set offset so 2nd, 3rd, etc gSEs don't overlap profiles. (e.g. offset = 300;)
