DDR-Less by Choice: HyperRAM & PSRAM for Embedded Systems

DRAM prices and lead times have been painful lately. If you've been shopping for memory for an embedded design in the last couple of years, you already know this.

What's worth revisiting is whether DDR was the right call in the first place. For a lot of designs such as camera buffers, image pipelines, DSP delay lines, IoT sensor logs, the working set sits comfortably in the 1-64MB range. The real constraints are pins, board space, and availability, and not bandwidth. HyperRAM and PSRAM were built for exactly this space and they're worth exploring as an alternative to DDR.

To make that case with actual numbers, this talk includes benchmarks like latency measurement, burst throughput, and sleep current across DDR, HyperRAM, and PSRAM side by side, and not generic datasheet estimates. From those numbers we work through a decision framework for when each technology earns its place.

To demonstrate this we have benchmarked HyperRAM on the Texas Instruments AM275x using its native HyperBus controller, and PSRAM on the AM243x via the OSPI controller.

1. DDR is often overkill for working sets in the 1–64 MB range, since we're paying in pins, board space, and cost for bandwidth which we don't use.

2. HyperRAM and PSRAM are serious alternatives, they are not just niche parts; they cover a wide range of real embedded use cases (camera buffers, DSP pipelines, sensor logs).

3. Fewer pins means real savings: HyperRAM needs 13 pins vs DDR's 40+; which shrinks the PCB , package size, and routing complexity being used.

4. HyperRAM and PSRAM supports execute-in-place, letting you run code directly from external memory and simplifying your boot and memory layout.

5. The benchmarks have also been validated on TI silicon: AM275x (HyperBus) and AM243x (OSPI), so the numbers are reproducible, and not just theoretical.

6. This talk gives embedded engineers a repeatable way to evaluate which technology belongs in their next design.