TMS320F2809, TMS320F2808, TMS320F2806
TMS320F2802, TMS320F2801, UCD9501
TMS320C2802, TMS320C2801, and TMS320F2801x DSPs
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SPRS230H–OCTOBER 2003–REVISED JUNE 2006
4.9 Serial Peripheral Interface (SPI) Modules (SPI-A, SPI-B, SPI-C, SPI-D)
The 280x devices include the four-pin serial peripheral interface (SPI) module. Up to four SPI modules
(SPI-A, SPI-B, SPI-C, and SPI-D) are available. The SPI is a high-speed, synchronous serial I/O port that
allows a serial bit stream of programmed length (one to sixteen bits) to be shifted into and out of the
device at a programmable bit-transfer rate. Normally, the SPI is used for communications between the
DSP controller and external peripherals or another processor. Typical applications include external I/O or
peripheral expansion through devices such as shift registers, display drivers, and ADCs. Multidevice
communications are supported by the master/slave operation of the SPI.
The SPI module features include:
•
Four external pins:
–
–
–
–
SPISOMI: SPI slave-output/master-input pin
SPISIMO: SPI slave-input/master-output pin
SPISTE: SPI slave transmit-enable pin
SPICLK: SPI serial-clock pin
NOTE: All four pins can be used as GPIO, if the SPI module is not used.
•
Two operational modes: master and slave
Baud rate: 125 different programmable rates.
LSPCLK
Baud rate =
when SPIBRR = 3 to 127
when SPIBRR = 0,1, 2
(SPIBRR ) 1)
LSPCLK
Baud rate =
4
•
•
Data word length: one to sixteen data bits
Four clocking schemes (controlled by clock polarity and clock phase bits) include:
–
–
–
–
Falling edge without phase delay: SPICLK active-high. SPI transmits data on the falling edge of the
SPICLK signal and receives data on the rising edge of the SPICLK signal.
Falling edge with phase delay: SPICLK active-high. SPI transmits data one half-cycle ahead of the
falling edge of the SPICLK signal and receives data on the falling edge of the SPICLK signal.
Rising edge without phase delay: SPICLK inactive-low. SPI transmits data on the rising edge of the
SPICLK signal and receives data on the falling edge of the SPICLK signal.
Rising edge with phase delay: SPICLK inactive-low. SPI transmits data one half-cycle ahead of the
falling edge of the SPICLK signal and receives data on the rising edge of the SPICLK signal.
•
•
Simultaneous receive and transmit operation (transmit function can be disabled in software)
Transmitter and receiver operations are accomplished through either interrupt-driven or polled
algorithms.
•
Nine SPI module control registers: Located in control register frame beginning at address 7040h.
NOTE
All registers in this module are 16-bit registers that are connected to Peripheral Frame 2.
When a register is accessed, the register data is in the lower byte (7-0), and the upper
byte (15-8) is read as zeros. Writing to the upper byte has no effect.
Enhanced feature:
•
•
16-level transmit/receive FIFO
Delayed transmit control
The SPI port operation is configured and controlled by the registers listed in Table 4-10.
Peripherals
73
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