CDB5550

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2.2.2 Setup Window

The Setup Window allows the user to access the internal registers of the CS5550. From this window the

user can click the View Register Values button to see the current values loaded in the Configuration,

Mask, Status, and Cycle Count Registers. The Status Register will default to 1h because the invalid com-

mand bit is active low. See Figure 4.

Figure 4. CDB5550 Setup Window

2.2.2.1. CS5550 Crystal Speed

The CS5550 accepts a wide range of crystal input frequencies, and can therefore run at many different

sample rates. The crystal frequency being used with the CS5550 should be entered in this box to provide

accurate frequency calculations in the FFT window. The CDB5550 comes with a 4.096 MHz crystal, which

is the default value in the Crystal Speed window.

2.2.2.2. Mask Register / Status Register

The Mask and Status Registers are displayed in hexadecimal and decoded in this box to indicate the func-

tion of each bit. The Mask Register can be modified by typing a value in the hexidecimal display box, or

by checking the appropriate check boxes for the bits that are to be masked. The Status Register cannot

be directly modified. It can only be reset by pressing the Clear Status Register button. The hexidecimal

display box for this register and the on-screen LEDs are read only. A LED that is on means that the cor-

responding bit in the Status Register is set (except the Invalid Command bit, which is inverted).

Note:

The value present in the Mask register may be changed by the software during certain operations to provide

correct functionality of the CDB5550 board.

2.2.2.3. Reading the Board ID EPROM

The CDB5550 utilizes an on-board EPROM that contains the board identification. This can be useful if the

same board can be used with multiple devices. By clicking on the “Read EPROM” button in the lower left

corner, the character string stored in the EPROM will be temporarily displayed. For the CDB5550, this

string will read, “CDB5550A0”.