AN970 Datasheet, PDF (9/10 Pages) STMicroelectronics – SPI COMMUNICATION BETWEEN ST7 AND EEPROM

SPI COMMUNICATION BETWEEN ST7 AND EEPROM
5.4 USE OF SEVERAL EEPROMS
It is possible to communicate with several EEPROMs. Each one is selected in turn. Then the
same protocol as described before is followed.
The main point is to reserve one I/O pin to select each device.
A hardware schematic using two devices is given below (Figure 4).
The selection of the devices is made using the PB2 and PB3 pins.
Figure 4. Hardware schematic for two devices
110pF
S
V_CC
Q
H
V_CC
W
C
V_SS
V_SS
D
M95040
V_CC
V_CC
110pF
1
V_CC
V_CC
V_SS
V_SS
SS(soft driven)
SCK
MISO
MOSI
PB3
PB2
S
V_CC
Q
H
V_CC
W
C
V_CC
V_CC
V_SS
V_SS
D
M95040
ST72264
5.5 SOFTWARE
All the source files in assembly code are given in the zip file with this application note.
The source files are for guidance only. STMicroelectronics shall not be held liable for any di-
rect, indirect or consequential damages with respect to any claims arising from use of this soft-
ware.
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