Title: Does the FSC-BT1026E support S/PDIF audio output?

Baursaque

Hello,

I am using the FSC-BT1026E module as an A2DP audio sink and would like to obtain the received Bluetooth audio stream through a digital S/PDIF output.

Could you please clarify:

Does the FSC-BT1026E support S/PDIF audio output?
Can S/PDIF be enabled through firmware configuration or AT commands?
Which module pin is used for the S/PDIF signal?
What output formats, sample rates, and bit depths are supported?
Is custom firmware required, or is this function available in the standard FSC-BT1026E firmware?
If direct S/PDIF output is not supported, can the decoded audio stream be output through I²S for conversion to S/PDIF using an external transmitter?

Thank you.

FAE_Gavin

Baursaque Yes, FSC-BT1026E supports S/PDIF audio output.

S/PDIF can be enabled by AT command:AT+SPDIFCFG=1 ; Disable:AT+SPDIFCFG=0

When S/PDIF output is enabled, I2S configuration will become invalid.

The S/PDIF output pin is:

SPDIF-OUT: Pin 15
SPDIF-IN: Pin 16

The S/PDIF output sample rate is adaptive according to the audio stream. No custom firmware is required; the standard FSC-BT1026E firmware supports this function.

More details can be found in the AT command manual:
https://document.feasycom.com/docs/audio/BT1026_EN/latest/index.html

Baursaque

Thank you for confirming that the FSC-BT1026E supports S/PDIF audio output through pin 15 using: AT+SPDIFCFG=1
I have reviewed the FSC-BT1026x Datasheet v1.7.2 and the General Audio AT Command Set 3.0.0. The remaining questions concern the hardware interface and runtime behavior.

What are the electrical characteristics of SPDIF_OUT on pin 15?
- Is it a CMOS logic-level signal referenced to VDD_IO?
- What is the typical output voltage?
- What is the output impedance and recommended drive strength?
Can pin 15 be connected directly to a standard 75-ohm coaxial S/PDIF input?
If not, could you provide the recommended output circuit, including:
- series resistor or resistor divider values;
- external logic buffer requirements;
- isolation transformer requirements;
- recommended 75-ohm termination or matching circuit.
Do you have an official reference schematic for the FSC-BT1026E S/PDIF output?
Is the AT+SPDIFCFG=1 setting stored in non-volatile memory and retained after complete power removal?
Is configuration readback supported with: AT+SPDIFCFG
If yes, what response should the module return?
When S/PDIF output is enabled, do the differential analog DAC outputs remain active at the same time?
Do the following controls affect the S/PDIF audio stream?
- AT+SPKVOL
- AT+SPKMUTE
- Bluetooth absolute volume
- internal EQ or DSP processing
What S/PDIF sample rate is normally produced for A2DP Sink playback?
- Is it fixed at 48 kHz?
- Does it follow the negotiated Bluetooth codec?
- Can it switch dynamically between 44.1 kHz and 48 kHz?
What PCM bit depth is transmitted through S/PDIF output?
What happens to the S/PDIF carrier when playback is paused or the A2DP stream disconnects?
continuous carrier with silence;
carrier disabled;
carrier restarted when playback resumes.
These details are required to design the production S/PDIF output stage correctly.

Thank you.

FAE_Gavin

Baursaque The currently available public documents for FSC-BT1026E include the datasheet and user guide, which cover the module specifications, interfaces, and supported functions.

You may refer to the following documents:

For additional technical details regarding S/PDIF hardware implementation, reference design, and specific firmware behavior, please contact our sales team for further technical support. Our team can evaluate your project requirements and provide appropriate assistance.

Baursaque

Hello Gavin! Does the SPDIF support commands that changes output sample rates? Like I2SCFG=5 for example

FAE_Gavin

Baursaque
Regarding your question about SPDIF and sample rate configuration:

SPDIF does not support commands like I2SCFG to manually change output sample rates. The sample rate on SPDIF is auto-adaptive — it adjusts automatically based on the incoming audio source or Bluetooth audio stream. No manual configuration is required or possible.