PT8401 Datasheet, PDF (9/28 Pages) Princeton Technology Corp – MP3 Audio Decoder

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MP3 Audio Decoder
PT8401
PARALLEL BITSTREAM INPUT INTERFACE
In addition to the serial interface, the microcontroller can also transmit bitstreams via parallel interface.
Parallel Mode is set via the Start-up Configuration or command register SP_SEL. Parallel data
transmission consists of the following signals:
1. PD_REQ : Parallel Data Request. A bundle of data may be requested and this is sent from
PT8401.
2. PD_ENA : Parallel Data Enable. This means that the data in the data bus is valid. This is sent
from microcontroller.
3. PD_ACK : Parallel Data Acknowledge. This means that the decoder has received one byte
successfully. This is sent from PT8401.
4. P_DATA : Parallel Data Bus is GPIO[15:8]. The GPIO15 is MSB and GPIO8 is LSB.
Due to some low speed transmission, the microcontroller may not be fast enough to know that PT8401
has closed communication. Please refer to the example described in Figure 6 wherein during the byte
7 transmission. In this example, PT8401 did not recognize an Acknowledge signal; thus, byte 7 was
not transmitted correctly.
In order to avoid instability, it is better not to set SP_SEL frequently.
PD_REQ
PD_ENA
PD_ACK
P_DATA[7:0]
B0
B1
B2
B6
B7
B8
Figure 7 : Parallel Data Transmission Timing
PT8401 v 1.3
Page 9
Updated March 2002