ST7LITE20F2 datasheet(21/166 Pages) STMICROELECTRONICS

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ST7LITE20F2 ST7LITE25F2 ST7LITE29F2

Flash program memory

Doc ID 8349 Rev 5

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Depending on the ICP driver code downloaded in RAM, Flash memory programming can be

fully customized (number of bytes to program, program locations, or selection of the serial

communication interface for downloading).

4.3.2

In-application programming (IAP)

This mode uses an IAP driver program previously programmed in Sector 0 by the user (in

ICP mode).

This mode is fully controlled by user software. This allows it to be adapted to the user

application, (user-defined strategy for entering programming mode, choice of

communications protocol used to fetch the data to be stored etc.).

IAP mode can be used to program any memory areas except Sector 0, which is write/erase

protected to allow recovery in case errors occur during the programming operation.

4.4

ICC interface

ICP needs a minimum of 4 and up to 6 pins to be connected to the programming tool. These

pins are:

●

RESET: device reset

●

VSS: device power supply ground

●

ICCCLK: ICC output serial clock pin

●

ICCDATA: ICC input serial data pin

●

CLKIN/PB4: main clock input for external source

●

VDD: application board power supply (optional).

If the ICCCLK or ICCDATA pins are only used as outputs in the application, no signal

isolation is necessary. As soon as the Programming Tool is plugged to the board, even if an

ICC session is not in progress, the ICCCLK and ICCDATA pins are not available for the

application. If they are used as inputs by the application, isolation such as a serial resistor

has to be implemented in case another device forces the signal. Refer to the Programming

Tool documentation for recommended resistor values.

During the ICP session, the programming tool must control the RESET pin. This can lead to

conflicts between the programming tool and the application reset circuit if it drives more than

5mA at high level (push pull output or pull-up resistor<1K). A schottky diode can be used to

isolate the application RESET circuit in this case. When using a classical RC network with

R>1 k

Ω or a reset management IC with open drain output and pull-up resistor > 1 kΩ, no

additional components are needed. In all cases the user must ensure that no external reset

is generated by the application during the ICC session.

The use of Pin 7 of the ICC connector depends on the Programming Tool architecture. This

pin must be connected when using most ST Programming Tools (it is used to monitor the

application power supply). Please refer to the Programming Tool manual.

Pin 9 has to be connected to the CLKIN/PB4 pin of the ST7 when the clock is not available

in the application or if the selected clock option is not programmed in the option byte. ST7

devices with multi-oscillator capability need to have OSC1 and OSC2 grounded in this case.

With any programming tool, while the ICP option is disabled, the external clock has to be

provided on PB4.

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