SAA5531 Philips Semiconductors, SAA5531 Datasheet - Page 39

• Manufacturer Part Number: SAA5531
• Description: Enhanced TV microcontrollers with On-Screen Display OSD
• Manufacturer: Philips Semiconductors

Philips Semiconductors
16 I
The I
serial clock line (SCL). The definition of the I
protocol can be found in Reference 2.
The device operates in four modes
The microcontroller peripheral is controlled by the Serial
Control SFR (S1CON) and its status is indicated by the
Status SFR (S1STA). Information is transmitted/received
to/from the I
Slave Address SFR (S1ADR) is used to configure the
slave address of the peripheral.
The byte level I
serial port on the P8xC558, except for the clock rate
selection bits CR<2:0>. The operation of the subsystem is
described in detail in the “P8xC558 data sheet”.
16.1
Two I
SCL1/SDA1. The selection of the port is done using
TXT21.I
port is enabled, any information transmitted from the
device goes onto the enabled port. Any information
transmitted to the device can only be acted on if the port is
enabled.
If both ports are enabled then data transmitted from the
device is seen on both ports, however data transmitted to
the device on one port can not be seen on the other port.
17 MEMORY INTERFACE
The memory interface controls access to the embedded
DRAM, refreshing of the DRAM and page clearing.
The DRAM is shared between Data Capture, display and
microcontroller sections.
The Data Capture section uses the DRAM to store
acquired information that has been requested. The display
reads from the DRAM information and converts it into RGB
values. The microcontroller uses the DRAM as embedded
auxiliary RAM.
2000 Feb 23
Master transmitter
Master receiver
Slave transmitter
Slave receiver.
Enhanced TV microcontrollers with
On-Screen Display (OSD)
2
2
2
C-BUS SERIAL I/O
C-bus consists of a serial data line (SDA) and a
C-bus ports are available SCL0/SDA0 and
I
2
2
C-bus port selection
C PORT 0 and TXT21.I
2
C-bus using the Data SFR (S1DAT) and the
2
C-bus serial port is identical to the I
2
C PORT 1. When the
2
C-bus
2
C-bus
39
17.1
The memory is partitioned into two distinct areas, the
dedicated Auxiliary RAM area, and the Display RAM area.
The Display RAM area when not being used for Data
Capture or display can be used as an extension to the
Auxiliary RAM area.
17.1.1
The Auxiliary RAM is not initialized at power-up.
The application software must initialize this Auxiliary RAM.
The contents of the Auxiliary RAM are maintained during
Idle mode, but are lost if Power-down mode is entered.
17.1.2
The Display RAM is initialised on power-up to a value of
20H throughout. The contents of the Display RAM are
maintained when entering Idle mode. If Idle mode is exited
using an interrupt then the contents are unchanged, if Idle
mode is exited using a RESET then the contents are
initialised to 20H.
Full Closed Caption display requires display RAM from
8000H to 845FH. The memory from 846H to 84FFH (must
be initialized by the application software) can be utilized as
an extension to the dedicated contiguous Auxiliary RAM
that occupies 0000H to 07FFH.
17.2
The dedicated Auxiliary RAM area occupies 2 kbytes, with
an address range from 0000H to 07FFH. The Display
RAM occupies a maximum of 10 kbytes with an address
range from 2000H to 47FFH for TXT mode and
8000H to 84FFH for CC mode (see Fig.14). The two
modes although having different address ranges occupy
physically the same DRAM area.
17.3
The memory can be addressed by the microcontroller in
two ways, either directly using a MOVX command, or via
Special Function Registers depending on what address is
required.
The dedicated Auxiliary RAM, and Display memory in the
range 8000H to 84FFH, can only be accessed using the
MOVX command.
The Display memory in the range 2000H to 47FFH can
either be directly accessed using the MOVX, or via the
Special Function Registers.
Memory structure
Memory mapping
Addressing memory
A
D
UXILIARY
ISPLAY
RAM
RAM
Preliminary specification
SAA55xx