Silicon Laboratories C8051F347 - Manual (Page 231)

Rev. 1.3 231
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate
SFR Definition 20.4. SPI0DAT: SPI0 Data
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is configured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is given in the following equation, where SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value held in the SPI0CKR register.
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA2
f
SCK
2000000
2 4 1 +
  
-------------------------- =
f
SCK
200kHz =
f
SCK
SYSCLK
2 SPI0CKR 1 +
  
------------------------------------------------- =
Bits 7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT
places the data into the transmit buffer and initiates a transfer when in Master Mode. A read
of SPI0DAT returns the contents of the receive buffer.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA3