Hardware implementation

AN2334

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5

Hardware implementation

The voltage regulator, which provides the required 5V during normal mode, is enabled by

the LIN transceiver through Inhibit Output pin INH. To reset the microcontroller with the

watchdog timer in case of a missing pulse, a jumper must be installed in the Voltage

Regulator Reset connector (#1 - Figure 8).

The jumper must be removed in case of microcontroller reprogramming; in fact, in this

phase, the microcontroller cannot provide pulses to the voltage regulator that should provide

a low level reset. Moreover, during the programming phase, to enable the Voltage regulator

a jumper must be installed in the Voltage Regulator Enable connector (#2 - Figure 8)

because in this case the LIN bus interface L9638 cannot provide the enabling voltage.

In summary, the microcontroller can be reprogrammed using the ICP connector (#10 -

Figure 8) by removing the Reset jumper (#1 - Figure 8) and settling the Enable jumper (#2 -

Figure 8). See the ST72F561 datasheet for more details.

A jumper on CB4 connector (#8 - Figure 8) allows using the board without using the LIN

Interface as detailed in Section 3: Local Interconnect Network (LIN) messages.

The board connector locations are given in Figure 8.

Figure 8.

Board connectors

1

1 Reset

2 Enable

3 L9950 Outputs

4 Down Key

5 Up Key

6 - CB5 / 7 – CB3 / 8 - CB4

9 - Window Up Switch

10 ICP Conn

11 Window

Motor

16 LIN Conn.

15 Wake Up

2

3

4

5

6

7

8

9

10

12 Power

Supply

13 L9950

Outputs

14 Parallel

Port

11

12

14

13

15

16

1

1 Reset

2 Enable

3 L9950 Outputs

4 Down Key

5 Up Key

6 - CB5 / 7 – CB3 / 8 - CB4

9 - Window Up Switch

10 ICP Conn

11 Window

Motor

16 LIN Conn.

15 Wake Up

2

3

4

5

6

7

8

9

10

12 Power

Supply

13 L9950

Outputs

14 Parallel

Port

11

12

14

13

15

16