at85c51snd3 ATMEL Corporation, at85c51snd3 Datasheet - Page 224

• Manufacturer Part Number: at85c51snd3
• Description: At85c51snd3 Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

Serial Peripheral
Interface
224
AT85C51SND3B
The AT85C51SND3B derivatives implement a Synchronous Peripheral Interface (SPI)
allowing full-duplex, synchronous, serial communication between the MCU and periph-
eral devices, including other MCUs.
Features of the SPI module include the following:
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Figure 114 shows a SPI bus configuration using the AT85C51SND3B as master con-
nected to slave peripherals while Figure 115 shows a SPI bus configuration using the
AT85C51SND3B as slave of an other master.
The bus is made of three wires connecting all the devices together:
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Each slave peripheral is selected by one Slave Select pin (SS). If there is only one
slave, it may be continuously selected with SS tied to a low level. Otherwise, the
AT85C51SND3B may select each device by software through port pins (Pn.x). Special
care should be taken not to select 2 slaves at the same time to avoid bus conflicts.
Figure 114. Typical Master SPI Bus Configuration
AT85C51SND3B
Full-duplex, three-wire synchronous transfers
Master or Slave operation
Programmable Master clock rates in master mode
Serial clock with programmable polarity and phase
Master Mode fault error flag with MCU interrupt capability
Master Output Slave Input (MOSI): it is used to transfer data in series from the
master to a slave.
It is driven by the master.
Master Input Slave Output (MISO): it is used to transfer data in series from a slave
to the master.
It is driven by the selected slave.
Serial Clock (SCK): it is used to synchronize the data transmission both in and out
the devices through their MOSI and MISO lines. It is driven by the master for eight
clock cycles which allows to exchange one byte on the serial lines.
Master
MISO
MOSI
SCK
Pn.z
Pn.y
Pn.x
SS
SO
DataFlash 1
SI
SCK
SS
SO
DataFlash 2
SI
SCK
SS
SO
7632D–MP3–01/07
Controller
SI
LCD
SCK