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Copyright 2012 Cirrus Logic, Inc.
DS886DB9
CDB47xxx Main Board System Description
CDB47xxx User’s Manual
1.3.9 C8051 MCU
The C8051 (U15) is a USB slave controller and general purpose MCU used to control the CDB47xxx
Board in stand-alone applications, and also used to interface to the PC through the USB port (DSP
Composer). Standalone applications can be as simple as using the MCU to configure the inputs on the
board to feed the DSP and provide a power-on-reset (POR) to the DSP. But standalone applications can
also take advantage of the LCD display, buttons, and rotary encoder to provide a user interface that is
managed by the C8051.
When DSP Composer is needed to perform real-time application development on the CS470xx, the USB
port should be used to connect the CDB47xxx Board to a PC that has DSP Composer
installed.
1.3.10 MCU Input: Push Buttons(S1-S4) and Rotary Encoder (S5)
The C8051 can accept user input through the buttons on the CDB47xxx when USB is not connected.
There are 4 momentary contact push-buttons provided.
There is also a rotary encoder knob that can be used to scroll up and down through options provided
through the MCU interface. The rotary encoder has an integrated momentary contact push-button that is
activated by pushing down on the knob.
1.3.11 MCU Output (LCD) (LCD1)
The C8051 can provide feedback to the user through the on-board LCD when USB is not connected.
1.3.12 Memory (U17, U16 and U14))
The CDB47xxx is assembled with a 32-Mbit SPI Flash (U17) and a 512-kbit I
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C Flash (U16) which are
dedicated for DSP firmware and configuration data. The serial control lines are routed down from the DSP
through the daughter-card connectors.
There is an additional 32-Mbit SPI Flash component on the board (U14) that is used only to store MCU
firmware, and it is not required by the DSP.
