Bliss-Box API (Application programming interface)

The 4-Play and the Gamer-Pro products have both a software and hardware Interface that can be used to communicate with the controller at both high and low levels. USB is a great solution, but it does have limitations. Also, the HID USB driver is even more limited in the sense of features vs a driver-based USB implementation. Bliss-Box products use HID for convenience, as dealing with drivers was never any fun, but also have an API for advanced features.  The mechanism for the API is in two parts (software and hardware).

The Software interface uses USB control transfers. This does still rely on the USB HID driver but allows data to be transferred that HID does not allow. For example but not limited to; Pressure buttons, LCD and memory pack data exchange, faster poll rates, and direct native talk to the controller. Bliss-Box has developed a software application that shows how this works. The application is an open source application that demos most all the API has to offer.  The source can be found here. And the application can be downloaded  here.

For the documented API see the following link.

List of projects using the API (If you would like to be added contact us)

Low Level API – (Only available on 3.0 for 4-play and GP)

LLAPI is a communication protocol develop internally by Bliss-Box LLC for Bliss-Box products. It has recently been made publicly available. The firmware only source code is available for this interface and is released under GPL v2 found here. This not to be confused with LLAPI (Low Latency API) a library developed for MiSTer cores to interact with Bliss-Box’s LLAPI protocol.

The LLAPI  uses the already available USB lines. To invoke the API, simply bring both d- and d+ high with external or internal pull ups.  This condition does not cause any hardware impeding conditions to existing USB hardware so it’s safe to use in both cases. When host device detects the condition, it will go in to bridge mode. So this can be asserted via software or hardware with a connected device.

Once in bridge mode, other devices using this protocol can send and receive data.

Timing Chart


List of projects using the LLAPI (If you would like to be added contact us). Mister LLAPI –  A core specific driver that communicates with Bliss-Box products.
BlisSTer – Bliss-Box’s very own MiSTer add-on.

Current support offered in the Bliss-Box adapters.

Command function parameters notes
0x00  CONTROLLER_POLL  Tells the connected controller to poll
0x01 GET_CONTROLLER_STATUS A 0x00 is require before this command is used
0x02 GET_PRESSURE_STATUS returns 12 button pressure levels.
0x03 GET_QUICK_STATES Bitmask of states
0x04 reserved
0x05 reserved
0x06 reserved
0x07 reserved
0x08 reserved
0x09 GET_LastCheckSum this is a xor of the 13 byes last read.
0x11 RUBMLE_CONST_START_FROM_PARMS Must set parms first in 0x1C
0x14 RUBMLE_SINE_START_FROM_PARMS Must set parms first in 0x1C
0x1C RUBMLE  duration, level Sets Rumble parameters.
0x20 SET_MODES bitmask Bitmask of modes link.
0x21 GET_MODES returns Bitmask of modes link.
0x22 SET_MAPPER 24 bytes Followed by 24 bytes each a button
0x23 SET_PLAYER ID (1,2,3,4) sets player ID
0x24 SET_ALT_MAP ALT_MAP sets the alternative mapping

Bitmask of States

bit 0 Gun Trigger
bit 1 Gun Light
bit 2 reserved
bit 3 reserved
bit 4 reserved
bit 5 reserved
bit 6 reserved
bit 7 reserved


Byte Data
0 Controller ID
1 Buttons 0-7
2  Buttons 8-15
3  Buttons 16-23
4  Analog X MAIN
5  Analog Y MAIN
6  Analog Z MAIN
7  Analog X Secondary
8  Analog Y Secondary
9  Analog Z Secondary
10  Slider
11  Dial
12  HAT


Byte Data
0 Player ID Pressure (0 – 255)
1 Button R Pressure (0 – 255)
2 Button L Pressure (0 – 255)
3 Button U Pressure (0 – 255)
4 Button D Pressure (0 – 255)
5 Button /\ Pressure (0 – 255)
6 Button 0 Pressure (0 – 255)
7 Button x  Pressure (0 – 255)
8 Button [] Pressure (0 – 255)
9 Button L1 Pressure (0 – 255)
10 Button R1 Pressure (0 – 255)
11 Button L2 Pressure (0 – 255)
12 Button R2 Pressure (0 – 255)

alt mappings options

ALT_MAP 0 – default




4-Alt (sega/nintendo)

Error replies

Error code type notes
0xF1 ERROR_UNKNOWN_COMMAND Command was not understood
0xFF ERROR_NO_COMMAND Error form the Bliss-Box side, retry, check controller.