CM120 C-Media Electronics, Inc., CM120 Datasheet - Page 27

• Manufacturer Part Number: CM120
• Description: Usb 7-in-1 Combo Card Reader Controller
• Manufacturer: C-Media Electronics, Inc.

Date: 09/09/2003
right hand side, communicating by means of three signal lines: SDIO, BS, and SCLK. Data and
command are converted on the SDIO, and regulation signals are controlled by host system via BS
and SCLK. Basically, the serial interface protocol have four bus states: BS0 – IDLE stage; BS1 –
TPC stage; BS2 – handshake or data stage; BS3 - handshake or data stage. Bus state sequence
are different between read and write operations.
sends the read command (all command called TPC here). During BS2 stage, MS card will tell the
host if it is ready to send the data. And when data is ready, it will be sent during BS3 stage combined
with 16bit CRC data. After all is done, both sides will return to BS0 stage and wait for another
command or interruption.
Above is the Memory Stick block diagram. Host is on the left hand side whereas MS card on the
Above is the MS read command running chart. It contains 4 stages: during BS1 stage, host
Figure 18: MS Serial Interface Block Diagram
Serial Interface for Memory Stick:
Figure 19: MS Read Protocol
- 26 -
USB 7-in-1 Combo Card Reader Controller
Version: 1.3
CM120