Cirrus-logic EV2 Manuel d'utilisateur télécharger pdf (Page 19)

CobraNet™ EV-2

19 Rev. 2.1

Sine Wave Generator

The FPGA contains a 32-sample, 24-bit, sine table. The table is stepped through at the

sample clock rate so the resulting fundamental frequency is 48kHz / 32 samples =

1500Hz and 3000Hz at 96kHz. Limited control over frequency and gain is provided.

Listed below are the values to write to the frequency and gain registers in the FPGA.

Frequency register data bits

AD3 AD2 AD1 AD0

Frequency

48kHz sample rate

(96kHz sample rate)

0 0 0 1 1.5 kHz (3.0 kHz)

0 0 1 0 3.0 kHz (6.0 kHz)

0 0 1 1 4.5 kHz (9.0 kHz)

0 1 0 0 6.0 kHz (12.0 kHz)

0 1 0 1 7.5 kHz (15.0 kHz)

0 1 1 0 9.0 kHz (18.0 kHz)

0 1 1 1 10.5 kHz (21.0 kHz)

1 0 0 0 12.0 kHz (24.0 kHz)

Table 8: Sine Wave Frequency Register Bit Definitions

Gain register data bits

AD1 AD0

Gain

000dB

0 1 -6dB

1 0 -12dB

1 1 -18dB

Table 9: Sine Wave Gain Register Bit Definitions

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 43 44

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Cirrus-logic EV2 Manuel d'utilisateur Page 19