SAA7750-N1D Datasheet, PDF (31/66 Pages) NXP Semiconductors – Generic device for portable multimedia applications

Philips Semiconductors
SAA7750-N1D
Preliminary Specification version 1.3
Generic device for portable
multimedia applications
E_RD = Enable / Read. Enable in 6800 mode, Read in 8080 mode.
RW_WR = ReadWrite / WRITE. Read/write in 6800 mode, Write in 8080 mode.
DB(7-0) = Data Bus.
SCL = Serial CLock.
SI = Serial Input.
SO = Serial Output.
7.16.3 RESETTING THE LCD CONTROLLER
Not all LCD controllers require a reset pin to reset the controller. In some cases a simple instruction to the controller is
enough to perform the reset.
A GPIO pin, or maybe the system reset can be used to act as a reset signal for the LCD controller, if it requires a hardware
reset pin.
7.16.4 OPERATIONAL MODES
The LCD_interface has three modes for outputting data: Byte-mode, 4-bit mode and serial-mode.
Byte mode:
At each shift of the FIFO, the last byte from the FIFO will be put on the data pins, and pin RS will indicate if the data is
an instruction or data value.
In read mode the data on pins DB_IN 7-0 will be sampled by the LCD_interface.
4-bit mode:
At each shift of the FIFO, the last byte from the FIFO will be split, where the order depends on the ‘MSB_first’ from the
control register.
When set to ‘1’, bit 7-4 from the FIFO byte will be put first, or read first, at the data pins, and then bit 3-0.
When set to ‘0’ bits 3-0 will be written or read first, and then bits 7-4.
7.16.5 SERIAL MODE:
At each shift of the FIFO the last FIFO byte will be split in 8 separate bits and be put on data pin 7, where the order
depends on the ‘MSB_first’ from the control register.
When set to ‘0’, then first bit 0 and last bit 7 will be written or read first, else the order is from 7 downto 0.
Signal RS is included for each 8 bits and indicates a instruction or data. Not all controllers require this signal in serial
mode, but can be used if required.
7.16.6 LOOPBACK MODE
Setting the register ‘LOOPBACK’ of the CONTROL register to ‘1’, will set the LCD interface in loopback-mode.
Internally, the LCD data output is connected to the LCD data input. The programmer can test correct behaviour of the
LCD interface, by doing the following:
• Place the LCD interface in parallel, 8-bit mode
• Write a single byte to the LCD_DATA_BYTE register
• Write ‘0x01’ to the LCD_READ_CMD register to request a bus read
• Poll the status bit, or wait for the ‘valid’ interrupt (if MASK is cleared)
• If valid, read the byte from LCD_DATA_BYTE register
• Compare this value with the written value
2002 Jan 21
31
PHILIPS CONFIDENTIAL