AY-3-8912 Emulator is a replacement board for the famous AY-3-8910/AY-3-8912/YM2149F sound chip of the ZX-Spectrum 128 and others. Based on the schematic and firmware from AVR-AY project, discussion on ZX-PK.ru and Turbo Sound schematic resources.
- Complete chip emulation (sound generation only)
- Parallel mode write/read operations support
- Serial mode write operations support
| Baud Rate | Data Bits | Stop Bits | Parity |
|---|---|---|---|
| 57600 | 8 | 1 | NONE |
Registers are sent as a pair of values: register number (0-13), then register value. To synchronize, just send 0xFF at the start of sending.
This sound chip emulator can be used in conjunction with the AVR-AY Player or PSG Tools. You will need the most ordinary USB to serial TTL converter. Just connect +5V, GND and TX pins of the converter to VCC, GND and RX pins of this emulation device, open corrsponding COM port in the player/tool and start playing music.
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The schematic of the device is quite simple. The heart of the emulator is a 8-bit ATmega series microcontroller, which runs at an overclocked frequency and performs low-level simulation of the sound chip. The rest of the device is three low-pass filters with a cutoff frequency of about 20 kHz, three communication interfaces and three output audio channels with analog signal waveform.
| Pin | Name | Function |
|---|---|---|
| 1 | GND |
Ground |
| 2 | VCC |
Power Supply (+5V) |
| 3 | TX |
Serial dada output (Speaker Input for AVR-AY) |
| 4 | RX |
Serial Data Input |
| Pin | Name | Function | Pin | Name | Function |
|---|---|---|---|---|---|
| 1 | C |
Analog Channel C | 28 | D0 |
Data/Address 0 |
| 2 | TEST |
no connection | 27 | D1 |
Data/Address 1 |
| 3 | VCC |
Power Supply (+5V) | 26 | D2 |
Data/Address 2 |
| 4 | B |
Analog Channel B | 25 | D3 |
Data/Address 3 |
| 5 | A |
Analog Channel A | 24 | D4 |
Data/Address 4 |
| 6 | GND |
Ground | 23 | D5 |
Data/Address 5 |
| 7 | IOA7 |
not implemented | 22 | D6 |
Data/Address 6 |
| 8 | IOA6 |
not implemented | 21 | D7 |
Data/Address 7 |
| 9 | IOA5 |
not implemented | 20 | BC1 |
Bus Control 1 |
| 10 | IOA4 |
not implemented | 19 | BC2 |
not implemented |
| 11 | IOA3 |
not implemented | 18 | BDIR |
Bus Direction |
| 12 | IOA2 |
not implemented | 17 | A8 |
not implemented |
| 13 | IOA1 |
not implemented | 16 | RES |
Reset (Low active) |
| 14 | IOA0 |
not implemented | 15 | CLK |
not implemented |
| Pin | Name | Function | Pin | Name | Function |
|---|---|---|---|---|---|
| 1 | MISO |
Master In/Slave Out | 2 | VCC |
Power Supply |
| 3 | SCK |
Clock | 4 | MOSI |
Master Out/Slave In |
| 5 | RES |
Reset | 6 | GND |
Ground |
The default hardware configuration of the device assumes the use of an ATmega48PA microcontroller with a 27 MHz crystal resonator. According to feedbacks, it should work reliably. But you are free to use another microcontroller (ATmega8, ATmega88, ATmega168 and ATmega328) and a quartz resonator with another frequency (20 MHz, 24 MHz, 25 MHz, 28.332 MHz, 28 MHz, 30 MHz, 32 MHz and 40 MHz).
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