ST72104G, ST72215G, ST72216G, ST72254G
4 FLASH PROGRAM MEMORY
4.1 INTRODUCTION
This mode needs five signals (plus the V signal
if necessary) to be connected to the programming
tool. This signals are:
DD
FLASH devices have a single voltage non-volatile
FLASH memory that may be programmed in-situ
(or plugged in a programming tool) on a byte-by-
byte basis.
– RESET: device reset
– V : device ground power supply
SS
– ISPCLK: ISP output serial clock pin
– ISPDATA: ISP input serial data pin
4.2 MAIN FEATURES
– ISPSEL: Remote ISP mode selection. This pin
must be connected to V on the application
■ Remote In-Situ Programming (ISP) mode
■ Up to 16 bytes programmed in the same cycle
■ MTP memory (Multiple Time Programmable)
■ Read-out memory protection against piracy
SS
board through a pull-down resistor.
If any of these pins are used for other purposes on
the application, a serial resistor has to be imple-
mented to avoid a conflict if the other device forces
the signal level.
4.3 STRUCTURAL ORGANISATION
Figure 5 shows a typical hardware interface to a
standard ST7 programming tool. For more details
on the pin locations, refer to the device pinout de-
scription.
The FLASH program memory is organised in a
single 8-bit wide memory block which can be used
for storing both code and data constants.
Figure 5. Typical Remote ISP Interface
The FLASH program memory is mapped in the up-
per part of the ST7 addressing space and includes
the reset and interrupt user vector area .
HE10 CONNECTOR TYPE
TO PROGRAMMING TOOL
XTAL
4.4 IN-SITU PROGRAMMING (ISP) MODE
1
C
C
L1
L0
The FLASH program memory can be programmed
using Remote ISP mode. This ISP mode allows
the contents of the ST7 program memory to be up-
dated using a standard ST7 programming tools af-
ter the device is mounted on the application board.
This feature can be implemented with a minimum
number of added components and board area im-
pact.
ISPSEL
10KΩ
V
SS
RESET
ISPCLK
An example Remote ISP hardware interface to the
standard ST7 programming tool is described be-
low. For more details on ISP programming, refer to
the ST7 Programming Specification.
ST7
ISPDATA
47KΩ
Remote ISP Overview
The Remote ISP mode is initiated by a specific se-
quence on the dedicated ISPSEL pin.
APPLICATION
The Remote ISP is performed in three steps:
– Selection of the RAM execution mode
– Download of Remote ISP code in RAM
4.5 MEMORY READ-OUT PROTECTION
The read-out protection is enabled through an op-
tion bit.
– Execution of Remote ISP code in RAM to pro-
gram the user program into the FLASH
For FLASH devices, when this option is selected,
the program and data stored in the FLASH memo-
ry are protected against read-out piracy (including
a re-write protection). When this protection option
is removed the entire FLASH program memory is
first automatically erased. However, the E PROM
data memory (when available) can be protected
only with ROM devices.
Remote ISP hardware configuration
In Remote ISP mode, the ST7 has to be supplied
2
with power (V
cillator and application crystal circuit for example).
and V ) and a clock signal (os-
DD
SS
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ETC [ ETC ]
