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Flash program memory
ST7LITEUS2, ST7LITEUS5
Pin 9 has to be connected to the CLKIN pin of the ST7 when I
2
C mode is selected with
option bytes disabled (35-pulse I
2
C entry mode). When option bytes are enabled (38-pulse
I
2
C entry mode), the internal RC clock (internal RC or AWU RC) is forced. If internal RC is
selected in the option byte, the internal RC is provided. If AWU RC or external clock is
selected, the AWU RC oscillator is provided.
A serial resistor must be connected to I
2
C connector pin 6 in order to prevent contention on
PA3/RESET pin. Contention may occur if a tool forces a state on RESET pin while PA3 pin
forces the opposite state in output mode. The resistor value is defined to limit the current
below 2 mA at 5 V. If PA3 is used as output push-pull, then the application must be switched
off to allow the tool to take control of the RESET pin (PA3). To allow the programming tool to
drive the RESET pin below V
IL
, special care must also be taken when a pull-up is placed on
PA3 for application reasons.
Caution:
During normal operation, ICCCLK pin must be pulled- up, internally or externally (external
pull-up of 10 k
Ω
mandatory in noisy environment). This is to avoid entering I
2
C mode
unexpectedly during a reset. In the application, even if the pin is configured as output, any
reset will put it back in input pull-up.
Figure 6.
Typical I
2
C interface
4.5 Memory
protection
There are two different types of memory protection: readout protection and Write/Erase
Protection which can be applied individually.
4.5.1 Readout
protection
Readout protection, when selected provides a protection against program memory content
extraction and against write access to Flash memory. Even if no protection can be
considered as totally unbreakable, the feature provides a very high level of protection for a
general purpose microcontroller. Program memory is protected.
I
2
C CONNECTOR
ICC
D
A
T
A
IC
CCLK
RESET
V
DD
HE10 CONNECTOR TYPE
APPLICATION
POWER SUPPLY
1
2
4
6
8
10
9
7
5
3
PROGRAMMING TOOL
I
2
C CONNECTOR
APPLICATION BOARD
I
2
C Cable
(See Note 3)
ST7
CL
KIN
OPTIONAL
See Note 1
See Note 1 and Caution
See Note 2
APPLICATION
RESET SOURCE
APPLICATION
I/O
(See Note 4)
3.3k
Ω
(See Note 5)
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