AT85C51SND3Bx
Clock Controller
Table 4. Clock Signal Description
Signal
Name
Alternate
Function
Type Description
Input of the on-chip inverting oscillator amplifier
To use the internal oscillator, a crystal/resonator circuit is connected to
this pin. If an external oscillator is used, its output is connected to this
pin. X1 is the clock source for internal timing.
X1
I
-
-
Output of the on-chip inverting oscillator amplifier
X2
O
To use the internal oscillator, a crystal/resonator circuit is connected to
this pin. If an external oscillator is used, leave X2 unconnected.
USB PLL Supply voltage
UPVDD
UPVSS
APVDD
APVSS
PWR
GND
PWR
GND
-
-
-
-
Connect this pin to LVDD pin.
USB PLL Circuit Ground
Connect this pin to LVSS pin.
Audio PLL Supply voltage
Connect this pin to LVDD pin.
Audio PLL Circuit Ground
Connect this pin to LVSS pin.
Memory Controllers
Table 5. Secure Digital Card / MutiMediaCard Controller Signal Description
Signal
Name
Alternate
Function
Type Description
SD/MMC Clock
SDCLK
O
P2.3
P2.2
Data or command clock transfer.
SD/MMC Command Line
SDCMD
I/O
Bidirectional command line used for commands and responses transfer.
SD/MMC Data Lines
SDDAT3:0 I/O
P2.7:4
P2.0
Bidirectional data lines. In 1-bit mode configuration SDDAT0 is the DAT
signal and SDDAT3:1 are not used and can be reused as I/O ports.
SD/MMC Card Insertion Signal
SDINS is the card presence signal. A low level on this input indicates
the card is present in its slot.
SDINS
SDLCK
I
I
Note:
This signal is generated by the SD/MMC card connector.
SD Card Write Lock Signal
SDLCK is the SD Card write protected input. A low level on this pin
indicates the card is write protected.
P2.1
Note:
This signal is generated by the SD/MMC card connector.
Table 6. Nand Flash / SmartMedia Card Controller Signal Description
Signal
Name
Alternate
Function
Type Description
Memory Data Bus
NFD7:0
I/O
O
-
-
8-bit bidirectional data bus.
Address Latch Enable Signal
NFALE
Asserted high during address write cycle.
9
7632A–MP3–03/06
ATMEL [ ATMEL ]
