AN1714 datasheet(30/46 Pages) STMICROELECTRONICS

30 / 46 page

Demonstration board for ST7538Q

AN1714

30/46

For some general considerations or a protection components list refer to the annexed

application notes and documentation.

2.6

ST7 microcontroller and RS232 interface

To complete an application for the powerline communication a microprocessor must

manage the upper layer of the communication protocol and eventually process other signals

related to the application (signal from sensors, current measures, driving actuators, and so

on). A different type of microcontroller can be required depending on the specific

application.

The demonstration board has a ST72C334J2 or ST72C334J4 microprocessor. This

component is connected to the ST232 driver interface and to the ST7538Q.

The loaded firmware has the function to receive from the PC program interface (through the

standard RS232 serial port) some commands to manage the control register writing and

reading procedures as well as the transmitting and receiving functions of the modem. The

results of the executed command come back to the PC program interface and are displayed

on the monitor.

Figure 27.

Microcontroller/RS232 interface

The ST7 microprocessor controls also the LED diodes D9, D10, D11, D12. The D9 (red) is

turned on during a transmission condition; the green LED D12 is turned on when the

receiving mode is activated. The D10 yellow diode is switched on when the Band-in-Use

signal is active. The D11 LED (red) is on when a Timeout event occurs. To save power

consumption the LEDs are turned off by removing jumper J9.

The ST7 firmware can be customized. Some of the I/O digital pins or analog input pins of

the microprocessor, that can be used to monitor some external signal or sensors and to

drive relays or other external devices, are available at the connector CN6.

The connector CN7 is used for ST7 memory in-situ programming. For a correct

programming procedure the ST7538Q has to be supplied, we suggest using an external 10

V supply from the connector CN2. The jumper J11 has to be opened.

ST72C334

CN5

PC INTERFACE

PE0/TD0

PE1/RDI

ANI0/PD0

T1IN

R1OUT

T2IN

ST232

T1OUT

T2OUT

R1IN

R1IN_A

T1OUT_A

T2OUT_A

PA7

PA6

PA5

PA4

RN1

D11

D12

D10

5V_led

PE0/TD0

PE1/RDI

ANI0/PD0

T2OUT

PA7

PA6

PA5

PA4

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