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emmc-module

Also known as: eMMC, eMMC module, FORESEE eMMC, soldered eMMC

Description

An eMMC module is a BGA/soldered managed-NAND package (JEDEC eMMC 5.1) that speaks the same SD/MMC protocol as a microSD card but with no socket and an 8-bit data bus. On the esp32-s3 SDMMC host it is the reliability upgrade over an industrial microSD: no mechanical socket to vibrate loose, LDPC ECC + wear-levelling + bad-block management in a soldered part, and an 8-line bus (vs the card's 4-line). It is the right medium for a node that must survive a month of continuous CSI logging unattended (EXP-F2 drift study).

The stored reference is the Longsys FORESEE embedded-storage catalogue (eMMC + pSLC industrial line) as a representative part.

Capabilities

Marked from the FORESEE catalogue (foresee-emmc.pdf) + JEDEC eMMC 5.1.

Spec Value Source
Standard JEDEC eMMC 5.1 catalogue
Bus width 1 / 4 / 8-bit JEDEC
Rated speed modes HS400 / HS200 (1.8 V) — not reachable on ESP32-S3 JEDEC
Speed on ESP32-S3 SDMMC High-Speed DDR52 (≈ 52 MHz), 8-line, 3.3 V ESP-IDF SDMMC host
Managed-NAND features LDPC ECC, dynamic + static wear-levelling, bad-block mgmt, power-loss protection catalogue
NAND options 3D-TLC or pSLC (industrial) catalogue
Temp grade commercial / industrial (−40 … +85 °C) / automotive AEC-Q100 lines catalogue
Form factor soldered BGA (no socket) —

Quirks / known issues

  • 1.8 V HS200/HS400 is unreachable on ESP32-S3 (3.3 V SDMMC) — do not spec eMMC expecting 200+ MB/s here.
  • Soldered part → no field-swappable log medium; retrieve data over USB/SPI/Wi-Fi instead of pulling a card. Trade-off vs industrial-microsd.
  • Boot/partition semantics differ from SD; mount with esp_vfs_fat_sdmmc_mount in eMMC mode, not the SD-card path.
  • Needs board-level layout (8 lines + power) — more work than dropping a microSD socket; justify with the reliability requirement.

Used by (devices)

  • esp32-c5-s3-csi-logger — reliability-grade log medium (alternative to the microSD socket)
  • esp32-c6-s3-csi-logger — same
  • esp32-s3 — the SDMMC host (3.3 V, DDR52 ceiling)
  • industrial-microsd — socketed alternative; same host-limited throughput regime