Comparison Item | DDR3 (Traditional Solution) | PSRAM (Alternative Solution) | Conclusion for Smart Speakers |
Interface | Parallel DDR interface requiring PHY and complex clock/routing | QSPI/OPI serial interface with only 6–8 pins, no PHY needed | PSRAM enables extremely simple hardware design, lower PCB cost, and easier routing |
Bandwidth | 12.8GB/s (DDR3-1600) | QSPI: ~532Mbps; OPI: ~1.6Gbps | Sufficient for audio decoding, microphone array buffering, and AEC/NS algorithms; meets lossless audio and multi-mic scenarios |
Capacity | 64MB–512MB (mainstream) | 8MB–64MB (64Mbit–512Mbit) | Covers entry-level to mid-range memory requirements for smart speakers; high-end configurations can use multiple chips in parallel |
Refresh | Requires periodic refresh by the host, high software complexity | Built-in self-refresh, transparent to the system, no software intervention | PHigher development efficiency with PSRAM, enabling fast Linux porting |
Supply & Cost | Shortages, large price fluctuations, long lead times | Stable supply, lower cost | PSRAM resolves supply shortages and significantly reduces BOM cost |
Power Consumption | High dynamic power consumption, average standby power | Low dynamic power consumption, ultra-low standby power | Ideal for battery-powered and low-power speaker designs |
Far-field voice capture (4/6/8-mic arrays): PSRAM can buffer multi-channel audio sampling data and meet the historical frame buffering requirements of AEC/NS and dual-wakeword algorithms.
Local + cloud dual wakeword / VAD: Hardware VAD with PSRAM buffering eliminates frequent Flash access, providing the same wake response speed as DDR3 solutions.
Multi-format audio decoding (MP3/FLAC/AAC/APE): PSRAM bandwidth supports high-spec lossless decoding, with decoding buffers resident in PSRAM for smooth playback.
Linux + voice SDK (Baidu / Alibaba / iFlyTek): PSRAM acts as system cache and algorithm memory pool. After Linux kernel optimization, the voice system runs stably.
Bluetooth / Wi-Fi / DLNA / AirPlay: Network protocol stacks and audio streams can be buffered in PSRAM, ensuring smooth multitasking and supporting wireless audio casting.
QSPI mode: Connect to RK3308 QSPI_CLK, CS, IO0–IO3 (6 pins total), no extra control signals required.
OPI mode: Connect IO0–IO7 (8 pins), doubling bandwidth for high-bitrate audio scenarios.
Power supply: 1.8V, compatible with RK3308 I/O voltage, no level shifter needed.
PCB design: Simple serial routing allows 2-layer boards, greatly reducing cost compared to DDR3’s 4–6-layer boards.
PSRAM dedicated area: Allocate the majority of PSRAM for audio buffers, mic array buffering, and AEC/NS algorithm memory pools.
System runtime area: Reserve remaining space for the Linux kernel, processes, and network protocol stacks.
Disable swap partition: Due to limited PSRAM bandwidth, swap is disabled to avoid performance degradation.
Enable DMA data transfer: I2S audio streams and mic array data are written directly to PSRAM via DMA with zero CPU intervention, improving real-time performance.
Optimize audio decoding libraries: Decoding buffers reside in PSRAM to reduce Flash access and ensure controllable decoding latency.
Host: Standard RK3308
PSRAM capacity: Low-capacity PSRAM
System: Optimized Linux + lightweight voice SDK
Advantage: Lowest cost, most stable supply, meets basic entry-level needs
Host: Industrial RK3308B (with CAN, suitable for gateway scenarios)
PSRAM capacity: Mid-capacity PSRAM, OPI interface recommended
System: Full Linux + mainstream voice SDK
Advantage: Sufficient bandwidth, stable operation, ideal for mass-production mainstream configurations
Host: Industrial RK3308B
PSRAM capacity: High-capacity PSRAM or multiple chips in parallel
System: Full Linux + full-featured voice SDK + high-definition audio decoding
Advantage: Performance close to DDR3 solutions, with clear supply and cost benefits
Supply chain relief: Solves DDR3 shortages and long lead times; PSRAM supply is stable to ensure continuous mass production.
Significant cost reduction: Lower BOM and PCB costs, ideal for high-volume smart speaker products.
Perfect scenario matching: Bandwidth and capacity fully cover audio decoding and complex application needs of RK3308 smart speakers and voice control panels.
Low migration cost: Native QSPI/OPI PSRAM support on RK3308, mature Linux drivers, and minimal software adaptation effort.
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