Altera cyclone V Technical Reference page 984

Hard processor system

Hide thumbs Also See for cyclone V:

Table of Contents

Voltage Switching

Figure 14-11: Voltage Switching Command Flow Diagram

(*1) Note: Card returns busy when:

• Card executes internal initializaiton process

• Card is High or Extended capacity SD Memory Card and host does not support High

The following outlines the steps for the voltage switch programming sequence.

1. Software Driver starts CMD0, which selects the bus mode as SD.

2. After the bus is in SD card mode, CMD8 is started in order to verify if the card is compatible with the

SD Memory Card Specification, Version 2.00.

CMD8 determines if the card is capable of working within the host supply voltage specified in the VHS

(19:16) field of the CMD; the card supports the current host voltage if a response to CMD8 is received.

3. ACMD 41 is started.

The response to this command informs the software if the card supports voltage switching; bits 38, 36,

and 32 are checked by the card argument of ACMD41.

Altera Corporation

SD/MMC Controller

Send Feedback

Show Quick Links

Table of Contents