Sd Matrix - Sferalabs strato Pi CM Duo v3 User Manual

RS-485 JUMPERS AND SWITCH POSITION

SD matrix

Strato Pi CM Duo implements a flexible dual microSD card architecture.
Strato Pi CM routes its two microSD card holders to the Compute Module through a high-
speed switching matrix, controlled by the on-board micro-controller. Each SD card can be
set as the boot card, with the other available as additional storage.
This enables for separate OS/data storage, SD redundancy and in-field full-system
upgrades.
The BCM283x in the Raspberry Pi Compute Module supports two SD card interfaces, SD0
and SD1.
The first (SD0) is a proprietary Broadcom controller that does not support SDIO and is the
primary interface used to boot and talk to the eMMC or SDX signals. The CM will always
try to boot from this interface first.
The second interface (SD1) is standards compliant and can interface to SD, SDIO and
eMMC devices.
Both interfaces can support speeds up to 50MHz single ended (SD High Speed Mode),
and this speed is supported by the Strato Pi CM Duo SD matrix as well.
Strato Pi CM Duo has two microSD slots, called SDA (bottom) and SDB (top), and the SD
matrix allows 2x2 connections between both SDX/SD1 interfaces and the SDA/SDB slots.
NOTICE
Disconnecting an SD card from the Compute Module's SD interfaces when partitions from
the card are mounted at the operating system level, can result in file system and data
21 Strato Pi CM Duo v3 User Guide