AN2451
Board description
Doc ID 12791 Rev 3
35/55
5.6
50-pin connector for the EVALCOMMBOARD
Figure 32.
Scheme of the connector for the EVALCOMMBOARD
The ST7540 transceiver requires external digital control to communicate. This is done
through an ST7 microcontroller which is accommodated on the EVALCOMMBOARD (see
). Communication with the ST7 microcontroller involves several
signals, which can be gathered into 3 groups: Digital signals, Analog signals and Power
connections. The signals for each group are listed in
,
. Besides
the ST7540 input and output signals, the link to the EVALCOMMBOARD includes:
●
A 2-bit (B_ID_PLM_1 and B_ID_PLM_0) Board Identification Code, which identifies the
hosted powerline transceiver. The microcontroller is able to recognize the ST7540
reference design board through a “10” binary configuration of this code.
●
An Analog Input (ANALOG_IN), which is a line intended to implement a Received
Signal Strength Indicator (a peak meter used to give an Rx signal level estimation).
●
A VDDF_FORCE signal, which forces the microcontroller to refer digital interface levels
to the VDDF (VDD) supply voltage provided by the ST7540 reference design board.
This way both the modem and the microcontroller “talk” on the same digital levels.
Table 7.
50-pin connector digital signals
Pin number
Signal name
Description
Generated by
20
B_ID_PLM_1
Board ID for PLM applications (MSB)
PLC Board (VDC)
28
B_ID_PLM_0
Board ID for PLM applications (LSB)
PLC Board (GND)
35
CD/PD
Carrier or preamble detected signal
Modem
37
REG_DATA
Data communication or register access
µC
39
RxD
Serial data output
Modem
40
RSTO
Reset output
Modem
Vcc
B_ID_PLM0
VDDF_FORCE
VDC
REG_DATA
CD/PD
RxD
BU/THERM
TxD
CLR/T
Rx/Tx
RSTO
UART/SPI
WD
GND
VDDF
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
CN2
CON50A
Vcc
B_ID_PLM1
GND
GND
ANALOG_IN
Vdd
VDC
