ST7573
7. FUNCTIONS DESCRIPTION
MICROPROCESSOR INTERFACE
Chip Select Input
The CSB pin is used for chip selection. ST7573 can interface with an MPU when CSB is "L". When CSB is “H”, the control
pins (A0, /RD and /WR) are disabled and D0 to D7 are set to be high impedance. If using serial interface, the internal shift
register and the counter are reset when CSB=”H”.
Parallel / Serial Interface
ST7573 has five types of interface to communicate with an MPU, which are three serial and two parallel interfaces. The
parallel or serial interface is determined by PS[2:0] pin as shown below.
Table 1
PS0
“L”
Parallel/Serial Interface Selection
PS2
“L”
PS1
“L”
CSB
A0
A0
"H"
A0
A0
State
CSB
CSB
CSB
CSB
4 Pin-SPI MPU interface
3 Pin-SPI MPU interface
“H”
“L”
“L”
“L”
“H”
“H”
“L”
8080-series parallel MPU interface
6800-series parallel MPU interface
“H”
“L”
Parallel Interface
The 8-bit bi-directional data bus is used in parallel interface and the type of MPU is selected by PS[2:0] as shown in Table 2.
The type of data transfer is determined by A0, ERD and RWR as shown in Table 3.
Table 2
Microprocessor Selection for Parallel Interface
PS2
H
PS1
H
PS0
CSB
CSB
CSB
A0
A0
A0
ERD
E
RWR
R/W
/WR
DB0 to DB7
DB0 to DB7
DB0 to DB7
MPU bus
6800-series
8080-series
L
L
L
H
/RD
Table 3
Parallel Data Transfer
8080-series
Common
6800-series
Description
E
R/W
/RD
(E)
/WR
A0
(/RD)
H
(/WR)
(R/W)
H
H
L
H
L
L
H
L
H
L
Display data read out
Display data write
H
H
H
L
H
L
Register status read
L
H
H
Writes to internal register (instruction)
NOTE: When ERD pin is always pulled high in 6800-series interface, the CSB can be used as enable signal. In this case,
interface data is latched at the rising edge of CSB and the access type is determined by A0, RWR as 6800-series mode.
Serial Interface
ST7573 supports 3 kinds of serial interface and the type is selected by PS2~PS0 as shown below.
Serial Mode
PS2
PS1
PS0
CSB
A0
4-line SPI interface
L
L
L
CSB
A0
Not Used
Fix to “H”
3-line SPI interface
H
L
L
CSB
Ver 1.0b
11/46
2007/07/12
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
