TMS320F28044 Datasheet, PDF (56/105 Pages) Texas Instruments – Digital Signal Processor

TMS320F28044
Digital Signal Processor
SPRS357A – AUGUST 2006 – REVISED OCTOBER 2006
www.ti.com
4.6 Serial Peripheral Interface (SPI) Module (SPI-A)
The 28044 device includes the four-pin serial peripheral interface (SPI) module. 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.
Baud rate =
LSPCLK
(SPIBRR ) 1)
when SPIBRR = 3 to 127
Baud rate =
LSPCLK
4
when SPIBRR = 0,1, 2
• 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 4-8.
56
Peripherals
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