AT89C51RD2 Atmel Corporation, AT89C51RD2 Datasheet - Page 69

• Manufacturer Part Number: AT89C51RD2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RD2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 32
• Spi: 1
• Uart: 1
• Sram (kbytes): 2
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

16.3.5
16.3.5.1
4235K–8051–05/08
Registers
Serial Peripheral Control Register (SPCON)
Serial Peripheral data transfer flag, SPIF: This bit is set by hardware when a transfer has been
completed. SPIF bit generates transmitter CPU interrupt requests.
Mode Fault flag, MODF: This bit becomes set to indicate that the level on the SS is inconsistent
with the mode of the SPI. MODF with SSDIS reset, generates receiver/error CPU interrupt
requests. When SSDIS is set, no MODF interrupt request is generated.
Figure 16-7 gives a logical view of the above statements.
Figure 16-7. SPI Interrupt Requests Generation
There are three registers in the Module that provide control, status and data storage functions. These registers are
describes in the following paragraphs.
Table 16-3 describes this register and explains the use of each bit
Table 16-3.
SPCON - Serial Peripheral Control Register (0C3H)
• The Serial Peripheral Control Register does the following:
• Selects one of the Master clock rates
• Configure the SPI Module as Master or Slave
• Selects serial clock polarity and phase
• Enables the SPI Module
• Frees the SS pin for a general-purpose
Bit Number
SPR2
7
7
6
5
SPIF
MODF
SSDIS
SPCON Register
SPEN
6
Bit Mnemonic
SSDIS
SPEN
SPR2
SSDIS
5
SPI Transmitter
CPU Interrupt Request
SPI Receiver/error
CPU Interrupt Request
Description
Serial Peripheral Rate 2
Bit with SPR1 and SPR0 define the clock rate.
Serial Peripheral Enable
Cleared to disable the SPI interface.
Set to enable the SPI interface.
SS Disable
Cleared to enable SS in both Master and Slave modes.
Set to disable SS in both Master and Slave modes. In Slave mode, this bit
has no effect if CPHA =’0’. When SSDIS is set, no MODF interrupt request
is generated
MSTR
4
.
CPOL
3
CPU Interrupt Request
AT89C51RD2/ED2
SPI
CPHA
2
SPR1
1
SPR0
0
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