AT85C51SND3Bx
Signal
Name
Alternate
Function
Type Description
Transmit Serial Data
TXD outputs the shift clock in serial I/O mode 0 and transmits data in
serial I/O modes 1, 2 and 3.
P3.1
TXD
RTS
O
O
MOSI
P3.2
INT0
SCK
Request To Send Hardware Handshake Line
Asserted low by hardware when SIO is ready to receive data.
P3.3
INT1
SS
Clear To Send Hardware Handshake Line
CTS
I
Asserted low by external hardware when SIO is allowed to send data.
MMI Interface
Table 13. Keypad Controller Signal Description
Signal
Name
Alternate
Function
Type Description
Keypad Input lines
KIN3:0
I
P1.3:0
Holding one of these pins high or low for 24 oscillator periods triggers a
keypad interrupt.
Table 14. LCD Interface Signal Description
Signal
Name
Alternate
Function
Type Description
Display Data Bus
P0.7:0
SD7:0
LD7:0
I/O
O
8-bit bidirectional data bus.
Read Signal/Enable Signal
P5.0
SRD
LRD/LDE
8080:
6800:
Read signal asserted low during display read access.
Enable signal asserted high during display access.
Write Signal/Read Write Signal
P5.3
8080:
6800:
Write signal asserted low during display write access.
Read/Write signal asserted low/high during display read/write
access
LWR/LRW
O
SWR
Display Chip Select
P5.1
SCS
LCS
O
O
Select signal asserted low during display access.
Display Address Bit 0/Register Select
P5.2
SA0
LA0/LRS
Address signal asserted during display access.
Power Management
Table 15. Power Signal Description
Signal
Name
Alternate
Function
Type Description
DC-DC Power ON Input
DCPWR
I
-
Connect DCPWR to VSS to start the DC-DC converter.
DC-DC Inductance Input
DCLI
PWR
PWR
Connect low ESR inductance to DCLI and BVDD.
Battery Supply Voltage
BVDD
-
Connect this pin to the positive pin of the battery.
13
7632A–MP3–03/06
ATMEL [ ATMEL ]
