SAA7750-N1D Datasheet, PDF (38/66 Pages) NXP Semiconductors – Generic device for portable multimedia applications

Philips Semiconductors
SAA7750-N1D
Preliminary Specification version 1.3
Generic device for portable
multimedia applications
7.19.4 Standard Serial Interface UART
The UART serial port in the CD decoder block is a full duplex interface. For each frame, 11 bits are transmitted (through
TXD) or received (through RXD): a start bit (logic 0), 8 data bits (LSB first), a parity bit and a stop bit (logic 1). Parity and
baud rate can be configured through the UART_CTRL registers (see table 207). Both transmit and receive have a
one-byte buffer that can be accessed through the UART_TX and the UART_RX registers, respectively. If enabled, an
interrupt is generated at each byte transmitted or received.
Baud rate is controlled through BaudRate field of UART_CONF1 register. It is effective for both transmit and receive. The
receive logic is able to tolerate a 5% baud-rate shift, provided that the HCLK frequency is correctly set in UART_CONF2
register.
All bits in UART_STATUS register can be cleared by writing a logic 1 to that bit, which also clears the interrupt associated
with that bit.
7.19.5 Subcode Interface
There are two subcode interfaces:
1. One that conforms to “EIAJ CP-2401” (using SBSY, SFSY, RCK and SUB) and can be configured as a 3 wire
interface. The interface formats are illustrated in Fig.9.
2. The Philips V4 format on V4 pin as illustrated in Fig.10. The subcode sync word is formed by a pause of 200 ms
minimum at nominal speed, where all subcode channels are muted. Each subcode byte starts with a 1 at the
P-channel bit position followed by 7 bits (Q to W), with P-channel bits discarded. The gap between two consecutive
bytes can vary from 11.3 ms to 90 ms.
The byte alignment is found by searching for a minimum gap of 200 ms (at nominal speed) on the V4 input. The gap is
counted against 12 rising edges of WSAB on the serial data interface (IIS or EIAJ). Once a start bit is detected, both
rising and falling edges of WSAB, in conjunction with CLAB, are used to synchronize the sampling of subcode data.
The 96-byte subcode data in a subcode frame is buffered in the subcode area of a 3KB buffer block. In addition, the 96-bit
Q-channel subcode is duplicated in a separate 12-byte area within the same block. The last 16 bits of the Q-channel
subcode are used internally to perform CRC.
2002 Jan 21
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PHILIPS CONFIDENTIAL