CM120 C-Media Electronics, Inc., CM120 Datasheet - Page 17

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

4. SYSTEM INTERFACE
Date: 09/09/2003
4.1 System
4.2 CLOCK Generator
4.3 RESETTING
(D+, D-, VBUS, GND) cable. The system interface of the signals connecting the CM120 is shown in
Figure 1. It includes clock generator, reset, processor, risc, fifo control, data memory, CF/Microdrive
interface, SmartMedia interface, SD/MMC interface, Memory Stick interface, SPI and GPIO.
through the XTAL1 pin. Internal PLL function provides 48MHz for USB operation.
decode the correct phase information. Subsequently, it is sampled on the receiver side of CM120 on
each immediately followed rising edge of PLL 48MHz clock.
All USB device command/status information intertransmit data over USB bus with four signals
CM120 generates its clock internally from an externally connected 12MHz crystal clock source
The beginning of all USB packets or frames transmitted over USB bus needs one 4X12 MHz to
There are 3 types of reset detailed under “Timing Characteristics”：
1. A Power-on reset where all CM120 logic (registers included) is initialized to its default state
2. A System reset where the contents of the CM120 register set are left unaltered
3. A Register reset which only initializes the CM120 registers to their default states
Figure 4. CM120 block diagram
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USB 7-in-1 Combo Card Reader Controller
Version: 1.3
CM120