ST AN1813 APPLICATION NOTE

	AN1813
®	APPLICATION NOTE

ST7 FLASH STICK and ST7MDTxx-EPB programmers In-Circuit Programming Considerations

INTRODUCTION

The In-Circuit Communication (ICC) protocol for ST7 makes it possible to in-circuit program your application to an ST7 XFLASH or HDFLASH microcontroller while the device is mounted on your application board.

Both the ST7 FLASH STICK and the ST7xxxx-EPB programmers allow in-circuit programming of supported ST7 Flash microcontrollers. However, when you start developing your application, you must integrate an ICC connector into your application hardware. To help you implement ICP in the development of your application, this application note provides a summary of points you should consider when installing an ICC connector.

1 ICC CONNECTION REQUIREMENTS

To connect to your application board for ICP, you need to install a 10-pin, HE-10 type connector. This connector receives the programming tool’s ICC cable and relays the required signals to the ST7 that is mounted on your application board.

Using the In-Circuit Communication (ICC) protocol for ICP requires that a minimum of 4 and as many as 6 pins of your ST7 be connected to the programming tool. These connection requirements are illustrated in Figure 1, below and summarized in Table 1 on page 2.

Figure 1: ICC Interface

HE-10 type connector

September 2004

DOC-AN1813-ICP

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ST7 Visual Debug

Application Note

Note: When using the ST7MDTS1-EPB, VDD_APPLI is not connected to the ST7. When setting up your application for in-circuit programming, refer to the ICP Interface diagram in the In-Circuit Programming section of the ST7SCR Datasheet, instead of the diagram provided in Figure 1.

	ST7 pin	Connects to
ICCDATA	ICC input serial data pin	ICCDATA
ICCCLK	ICC output serial clock pin	ICCCLK
RESET	Device reset	ICCRESET
ICCSEL/VPP	Programming voltage	ICCSEL/VPP
OSC1 or OSCIN * #	Main clock input for external	ICCOSC
VDD *	Device power supply	VDD_APPLI
VSS	Device power supply (ground)	GND

*Optional connection for the STICK, see text.

#Optional connection for ST7MDTxx-EPB, see text.

Table 1: ICC connection requirements

Isolation of ICCDATA and ICCCLK pins

As soon as an ICP tool is plugged into the application board the ICCDATA and ICCCLK pins must not be used by other application devices, even if an ICC session is not in progress. If the application uses these pins as inputs, isolation such as a serial resistor must be implemented to prevent other application devices from forcing a signal on either of these pins. The application board must not drive current in excess of 1mA.

If the ICCDATA and ICCCLK pins are only used as outputs by the application, no signal isolation is necessary.

For ST7 without an ICCSEL pin, during normal operation the ICCCLK pin must be pulled-up internally or externally (10KΩ pull-up required in noisy environments). This is to avoid entering ICC mode unintentionally during a reset.

Isolation of the RESET pin

During an ICC session, you must ensure that the programming tool controls the ST7’s RESET pin so that no external reset is generated by the application. This can lead to a conflict if the application reset circuitry signal exceeds 5mA (push-pull output or pull-up resistor <1k). To avoid such conflicts, a Shottky diode can be used to isolate the application reset circuit.

ICCSEL/VPP pin

The application pull-down resistor must not be lower than 10kΩ.

ICCOSC pin * #

The ICCOSC pin of the ICC connector must be connected to the ST7’s OSC1 or OSCIN pin if the clock is not provided by the application, or if the application clock source is not programmed in the option byte. This connection allows you to start your ICP session using the ICP OPT Disable programming mode. In this mode, the programming tool provides a clock source to initiate communication with the ST7. The STICK provides a clock source at a frequency of 8MHz; the ST7MDTxx-EPB clock frequency is 16MHz.

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