Serial Host Interface (SHI, SHI_1)
Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
Freescale Semiconductor
10-5
For the SHI interrupt vector table, see
For the exception priorities generated by the SHI, see
10.3.2
SHI Input/Output Shift Register (IOSR)—Host Side
The variable length Input/Output Shift Register (IOSR) can be viewed as a serial-to-parallel and
parallel-to-serial buffer in the SHI. The IOSR register is involved with every data transfer in both
directions (read and write). In compliance with the I
2
C and SPI bus protocols, the data is shifted in and out
MSB first. See
•
In 8-bit data transfer modes, the most significant byte of the IOSR is used as the shift register.
•
In 16-bit data transfer modes, the two most significant bytes become the shift register.
•
In 24-bit transfer modes, the shift register uses all three bytes of the IOSR.
NOTE
The IOSR register cannot be accessed directly either by the host processor
or by the DSP core. The IOSR register is fully controlled by the SHI
controller logic.
Table 10-1. SHI Interrupt Vectors
Program Address
Interrupt Source
VBA:$0040
SHI Transmit Data
VBA:$0042
SHI Transmit Underrun Error
VBA:$0044
SHI Receive FIFO Not Empty
VBA:$0048
SHI Receive FIFO Full
VBA:$004A
SHI Receive Overrun Error
VBA:$004C
SHI Bus Error
Table 10-2. SHI Internal Interrupt Priorities
Priority
Interrupt
Highest
SHI Bus Error
–
SHI Receive Overrun Error
–
SHI Transmit Underrun Error
–
SHI Receive FIFO Full
–
SHI Transmit Data
Lowest
SHI Receive FIFO Not Empty
Содержание Symphony DSP56724
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