Rainbow Electronics ATAR862-3 - Manual (Page 90)

90
ATAR862-3
4556B–4BMCU–02/03
Figure 95. MCL Protocol
• Before the START condition and after the STOP condition the device is in standby
mode and the SDA line is switched as input with pull-up resistor.
• The control byte that follows the START condition determines the following
operation. It consists of the 5-bit row address, 2 mode control bits and the
READ/NWRITE bit that is used to control the direction of the following transfer. A "0"
defines a write access and a "1" a read access.
Control Byte Format
EEPROM The EEPROM has a size of 512 bits and is organized as 32 x 16-bit matrix. To read and
write data to and from the EEPROM the serial interface must be used. The interface
supports one and two byte write accesses and one to n-byte read accesses to the
EEPROM.
EEPROM – Operating Modes The operating modes of the EEPROM are defined via the control byte. The control byte
contains the row address, the mode control bits and the read/not-write bit that is used to
control the direction of the following transfer. A "0" defines a write access and a "1" a
read access. The five address bits select one of the 32 rows of the EEPROM memory to
be accessed. For all accesses the complete 16-bit word of the selected row is loaded
into a buffer. The buffer must be read or overwritten via the serial interface. The two
mode control bits C1 and C2 define in which order the accesses to the buffer are per-
formed: High byte – low byte or low byte – high byte. The EEPROM also supports
autoincrement and autodecrement read operations. After sending the start address with
the corresponding mode, consecutive memory cells can be read row by row without
transmission of the row addresses.
Two special control bytes enable the complete initialization of EEPROM with "0" or
with "1".
Start
condition
Data
valid
Data
change
Data/
acknowledge
valid
Stop
condition
SCL
SDA
Stand
by
Stand-
by
EEPROM Address Mode
Control Bits
Read/
NWrite
Start A4 A3 A2 A1 A0 C1 C0 R/NW Ackn
Start Control byte Ackn Data byte Ackn Data byte Ackn Stop