AN987 datasheet(4/10 Pages) STMICROELECTRONICS

4 / 10 page

4/10

ST7 SERIAL TEST CONTROLLER PROGRAMMING

If these pins need to be tied to VDD or VSS, or if they are used by the user’s application, they

must be isolated from the user circuitry during programming. To do so, a jumper can be

added for each of the eight pins (see Figure 2.).

Note: Isolation resistors (47 k

Ω) can be used instead of jumpers only if these pins are used

by the application as input (without Pull-up, without pull-down, or analog input configura-

tion).

3 system pins, VPP/TEST, RESET and OSCIN, which must be connected as follows:

– The VPP/TEST pin must not be directly connected to GND/VSS on the application board

in order to avoid any conflict with the programming voltage. This pin should be pulled down

by a 10 k

Ω resistor (see Figure 2.).

– The RESET pin controls the entry into programming mode. This pin must be connected to

a 10 k

Ω pull-up resistor and a 1 nF capacitor connected to GND (see Figure 2.) to avoid

any direct connections to VSS. This pin can be connected to a 47 kΩ isolation resistor if an

external reset is provided by the application board.

– The OSCIN pin synchronizes the programming operation using a clock generated by the

programming tool. The OSCIN pin can be directly connected to the J1 connector. No iso-

lation is needed as long as a quartz crystal or ceramic resonator is used in the application.

If an external clock generator is used in the application, it must be disconnected during

STC programming.

Note: The OSCOUT pin does not need to be disconnected during the programming phase

as long as a crystal, a ceramic resonator or an external clock source is used to drive the

internal oscillator (user mode only).

The VDD and VSS power supply pins. The use of the VDD connection is optional, depending

on whether the application board supply can be disconnected or not.

If the application board supply is disconnected, the chip can be supplied through the

programming tool (as long as the total current load does not exceed 100 mA and the

capacitive load is less than 50 µF). In this case, only 1 jumper needs to be added in order to

disconnect the VPP pin from the user circuitry during the programming sequence. No jumper

is needed for VSS (see Figure 2.).

If you want to use the application board power supply, its voltage must be 5 V, so that logic

levels are compatible with those of the programming tool.

Note: In any case, the ground from the application board and the ground from the

programming tool must be connected together (see Figure 2.).

AN987 数据表(PDF) 4 Page - STMicroelectronics

AN987 数据表(HTML) 4 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10

数据表下载