Sundance SMT130 v.1.0 - Manual (Page 27)

User Manual (QCF42); Version 3.0, 8/11/00; © Sundance Multiprocessor Technology Ltd. 1999
12.3 DSP To Local Aperture 0 control and Accessing
The quickest way to transfer information from the DSP to PCI Bus or vice versa is to
use the Local-to-PCI Aperture 0 in the PCI Bridge device. A DSP unit may be
required to transfer large amounts of acquired data to the PC host for data storage or
post-processing etc. Allowing the DSP to take control of the PCI bus means that the
HOST only requires to transfer data, from an internal allocated region of memory,
after the transfer has been completed by the DSP. Alerting the Host that data has
been transferred can be accomplished in a number of ways i.e. writing to the mailbox
register, which can then generate an interrupt.
As shown in Table 4, section 5. The Local-to-PCI Aperture 0 is mapped as a region of
addressable space from 0x1800 0000 – 0x183F FFFF (words).
There are a number of registers in initialise before data can be read or written via this
address space.
• Unlock the PCI Bridge System register. This requires a write to
• Write the upper 8 bits of your destination address (in bytes) to the upper 8 bits
of the 32-bit Local Bus to PCI Map 0 register (LB_MAP0_RES, offset in bytes
0x5c ).
• Convert you lower 24-bit address to a word aligned value.
• Write/Read data from Local-to-PCI Aperture 0 .
The diagram below illustrates this procedure.
In the example below the WritetoPCIregisters(offset,data) function writes data over
the DSP’s Global bus, at a base address of 0x1800 0000 (words), the first parameter
passed to this function in the offset address in words, and the second is the data to
be written.