UNICORECOMM UM980 - Page 15

UM980 User Manual
10 Hardware UC-00-M32 EN R1.1
No.
Pin
I/O
Description
23
RSV
—
Reserved, recommended to be floating
24
NC
—
No connection inside
25
NC
—
No connection inside
26
RXD2
I
COM2 input, LVTTL level
27
TXD2
O
COM2 output, LVTTL level
28
BIF
—
Built-in function; recommended to add a
through-hole testing point and a 10 kΩ pull-
up resistor; cannot connect ground or power
supply, and cannot be peripheral I/O, but can
be floating
29
BIF
—
Built-in function; recommended to add a
through-hole testing point and a 10 kΩ pull-
up resistor; cannot connect ground or power
supply, and cannot be peripheral I/O, but can
be floating
30
TXD3
O
COM3 output, can be used as CAN TXD,
LVTTL level
31
RXD3
I
COM3 input, can be used as CAN RXD, LVTTL
level
32
GND
—
Ground
33
VCC
I
Power supply
34
VCC
I
Power supply
35
RSV
—
Reserved
36
V_BCKP
I
When the main power supply VCC is cut off,
V_BCKP supplies power to RTC and relevant
register. Level requirement: 2.0 V ~ 3.6 V, and
the working current should be less than 60
μA at 25 °C. If you do not use the hot start
function, connect V_BCKP to VCC. Do NOT