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2.12 Stereo Codec
A 16-bit audio quality stereo codec, Crystal Semiconductor CS4218, is connected to the
56F826's SSI port to support audio, voice and signal analysis applications. The codec is
clocked with a 12.288MHz oscillator allowing the codec to operate between a sample
frequency of 8kHz and 48kHz. The sample rate can be manually set using the appropriate
switch positions on dip switch S4. This three position dip switch makes the sample rate
selections detailed in
eliminating the need for voltage level translation circuitry. Additionally, a set of zero ohm
resistors are provided on the EVM to allow a user to disconnect the on-board codec from
the SSI port and to connect his own codec to the SSI port; see
codec has analog signal-conditioning logic, allowing direct connection to its line level
input and line level output signals through two 1/8" stereo jacks; reference
Position 3
2.12.1 Analog Input/Output
The 56F826EVM uses jacks for line level stereo input, line level stereo output and stereo
headphone output. A National Semiconductor LM4880 provides the drive required for the
use of headphones. This device offers a THD, which is superior to the CS4218's on-chip
headphone drive circuitry by a factor of two. The basic analog codec connections are
shown in
Figure
2-10.
MOTOROLA
Freescale Semiconductor, Inc.
Table 2-7
possible. The codec supports +3.3V digital levels,
Table 2-7. Codec Sample Rate Selector
SW 4
SW 4
Position 2
Position 3
(MF6)
(MF7)
ON
ON
ON
ON
ON
OFF
ON
OFF
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
Technical Summary
For More Information On This Product,
Go to: www.freescale.com
Figure
SW 4
Sample Rate
(MF8)
ON
48.00kHz
OFF
32.00kHz
ON
24.00kHz
OFF
19.20kHz
ON
16.00kHz
OFF
12.00kHz
ON
9.60kHz
OFF
8.00kHz
Stereo Codec
2-11. The on-board
Figure
2-10.
2-13
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