ver.1.0.0 / LastUpdate: 2017/8/26 19:57

YMF825Board Rev.A


This is a board with a Yamaha YMF825 (SD-1) mounted on it.
The SD-1 is a 4-operator, 16-voice polyphonic FM synthesizer chip.
Its registers can be controlled directly by SPI. The board has a crystal unit. The chip has a DAC and an amplifier.
You can generate sound by only manipulating the registers.


・3.5mm Headphone jack
・12.288MHz crystal unit
・YMF825 chipset
 ・Integrated loudspeaker driver
 ・Synchronous serial data link for host controller interface (SPI compatible)
 ・FM tone generator
 ・Integrated 3-band equalizer
・IOVDD(switching 5V / 3.3V)

Design Data


Layout view(Top of view)

Power Supply

Single 5V Power Supply Configuration

No changes to the schematic are necessary.
Please connect the power supply to 5V and GND.
The 3.3V terminal will not be used.

Dual Power Supply(5V/3.3V) Configuration

Please connect a power supply to 3.3V (separately from 5V).
Remove the R0 resistor.
Short S1 with solder. 


Terminal List

Terminal Number / Function Name Description
0: SS Slave Selection of Serial Interface (Chip Select)
1: MOSI Master Out, Slave In of Serial Interface, Input of YMF825Board
2: MISO Master In, Slave Out of Serial Interface, Output of YMF825Board
3: SCK Serial Interface Clock
4: GND Ground of referenced voltage
5: 5V 5V power supply input
6: RST_N Reset the YMF825. Can be left unconnected because the YMF85 has a power-on reset and a software reset function.
7: AUDIO LINE Output. Refer to the schematic.
8: 3.3V 3.3V power supply input. In the case of the dual power supply.

Hardware Specification

Item Description
Speaker Output 0.9W 8Ω
Serial Interface MAX 10MHz
Vih 0.8 x IOVDD
Vil 0.2 x IOVDD
5V 4.5V〜5.5V
3.3V 3.0V〜3.6V
Operating temperature range -20℃ -- 85℃

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