12.2 System-Level Integration
This section describes the various functionality that is applicable to the device integration. These features require
configuration of other modules in the device that are not within the scope of this chapter.
12.2.1 SPI Module Signals
classifies and provides a summary of the SPI module signals.
Table 12-1. SPI Module Signal Summary
Signal Name
Description
External Signals
SPICLK
SPI clock
SPISIMO
SPI slave in, master out
SPISOMI
SPI slave out, master in
SPISTE
SPI slave transmit enable
Control
SPI Clock Rate
LSPCLK
Interrupt Signals
SPIINT/SPIRXINT
Transmit interrupt/ Receive Interrupt in non FIFO mode (referred to as SPIINT)
Receive interrupt in FIFO mode
SPITXINT
Transmit interrupt in FIFO mode
Special Considerations
The SPISTE signal provides the ability to gate any spurious clock and data pulses when the SPI is in slave
mode. A HIGH logic signal on SPISTE will not allow the slave to receive data. This prevents the SPI slave from
losing synchronization with the master. It is this reason that TI does not recommend that the SPISTE always be
tied to the active state.
If the SPI slave does ever lose synchronization with the master, toggling SPISWRESET resets the internal bit
counter as well as the various status flags in the module. By resetting the bit counter, the SPI interprets the next
clock transition as the first bit of a new transmission. The register bit fields that are reset by SPISWRESET are
found in
Configuring a GPIO to Emulate SPISTE
In many systems, a SPI master may be connected to multiple SPI slaves using multiple instances of SPISTE.
Though this SPI module does not natively support multiple SPISTE signals, it is possible to emulate this
behavior in software using GPIOs. In this configuration, the SPI must be configured as the master. Rather than
using the GPIO Mux to select SPISTE, the application would configure pins to be GPIO outputs, one GPIO
per SPI slave. Before transmitting any data, the application would drive the desired GPIO to the active state.
Immediately after the transmission has been completed, the GPIO chip select would be driven to the inactive
state. This process can be repeated for many slaves that share the SPICLK, SPISIMO, and SPISOMI lines.
12.2.2 Configuring Device Pins
The GPIO mux registers must be configured to connect this peripheral to the device pins.
Some IO functionality is defined by GPIO register settings independent of this peripheral. For input signals, the
GPIO input qualification should be set to asynchronous mode by setting the appropriate GPxQSELn register bits
to 11b. The internal pullups can be configured in the GPyPUD register.
See the
GPIO
chapter for more details on GPIO mux and settings.
Serial Peripheral Interface (SPI)
762
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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