Product manual

Industrial Grade SD Card Interface Description
SanDisk Industrial Grade SD Product Manual, Rev. 1.0 © 2003 SANDISK CORPORATION -3-3
Figure 3-1. Industrial Grade SD Card Architecture
3.2. SD Bus Topology
The SD bus has six communication lines and three supply lines:
• CMD—Command is a bi-directional signal. (Host and card drivers are operating in push pull mode.)
• DAT0-3—Data lines are bi-directional signals. (Host and card drivers are operating in push pull
mode.)
• CLK—Clock is a host to cards signal. (CLK operates in push pull mode.)
• VDD—VDD is the power supply line for all cards.
• VSS[1:2]—VSS are two ground lines.