
Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
10-2
Freescale Semiconductor
Serial Host Interface (SHI, SHI_1)
•
Generate vectored interrupts separately for receive and transmit events, and update status bits
•
Generate a separate vectored interrupt for a receive exception
•
Generate a separate vectored interrupt for a bus error exception
•
Generate the clock signal (in master mode)
•
Trigger DMA interrupts to service the transmit and receive events
10.2
Serial Host Interface Internal Architecture
The DSP core views the SHI as a memory-mapped peripheral in the X data memory space. The DSP uses
the SHI as a normal memory-mapped peripheral using standard polling, interrupt programming
techniques, or DMA transfers. Memory mapping enables the DSP to communicate with the SHI registers
using standard instructions and addressing modes. In addition, the MOVEP instruction allows
interface-to-memory and memory-to-interface data transfers without going through an intermediate
register. The DMA controller can be used to service the receive or transmit data paths. The single master
configuration allows the DSP to directly connect to dumb peripheral devices; for that purpose, a
programmable baud-rate generator is included to generate the clock signal for serial transfers. The host
side invokes the SHI for communication and data transfers with the DSP through a shift register that can
be accessed serially, using either the I
2
C or the SPI bus protocols.
shows the SHI block
diagram.
Figure 10-1. Serial Host Interface Block Diagram
Input/Output Shift Register
(IOSR)
Host-Accessible
Clock
Generator
DSP-Accessible
SCK/SCL
MISO/SDA
MOSI/HA0
SS/HA2
HREQ
Slave Address
Recognition Unit
(SAR)
HRX
(FIFO)
HSAR
HTX
HCSR
HCKR
DSP Global
Data Bus
24-Bit
Controller
Logic
DSP Global
DMA Data
Bus
Pin
Control
Logic
Legend: