Memory Control Circuit - Sanyo AVM-2550S Training Manual

The VB7C chassis is equipped with a nonvolatile memory IC to store certain
information that should remain intact through a power failure. IC802 is the 2K
bit serial EEPROM used to store this information. An EEPROM or E2PROM
is an Electrical Erasable Programmable Read Only Memory integrated circuit.
IC802 will store Channel Memory, including active and inactive channels for
total of 125 channels, the Air/Cable mode, the customer settings of Digital
Control, Caption mode, Language mode, TV/AV mode, Surround On/Off
mode, Color Enhancer mode, the Line-SW On/Off mode, and the BUS data
used for factory/service adjustments. (The Line-SW On/Off mode is a special
mode used only for production.)

MEMORY CONTROL CIRCUIT

IC801
CPU
IIC
33
SCL
IIC
31
SDA
Memory Control Circuit
Control of the memory IC is through CPU pins 31 and 33.
Pin 33 is the IIC SCL (Serial Clock) signal. The IIC SCL input is used to clock
all data into and out of IC802.
Pin 31 is the IIC SDA (Serial Data) signal. The IIC SDA is a bidirectional
signal and is used to transfer data into and out of memory. Data is processed
through an 8 bit read or write for each address and there are 256 addresses.
Therefore, IC802 has a capacity of 256 x 8 or 2K bits of data.
ALWAYS
5V
L801
C801
R808
R807
– 28 –
IC802
EEPROM
6
SCL
5
SDA