Sundance SMT310Q - Manual (Page 25)

Version 2.1 Page 25 of 55 SMT310Q User Manual
7.3
DSP To Local Aperture 0 control and Accessing
The quickest way to transfer information between the DSP and PCI Bus is to
use the Local-to-PCI Aperture 0 in the PCI bridge device.
A DSP may need to transfer large amounts of acquired data to the PC host for
data storage or post-processing. Allowing the DSP to take control of the PCI
bus means that the HOST only needs to be involved once the data have been
transferred by the DSP to PC memory. Alerting the Host that data have been
transferred can be accomplished in a number of ways, for example, by writing to
a mailbox register to generate an interrupt.
The Local-to-PCI Aperture 0 is mapped as a region of addressable space from
18000000
16
–183FFFFF
16
(words), as shown in Table 4, section 5.
There are several registers to initialise before data can be read or written via
this address space:
• Unlock the PCI Bridge System register. This requires a write to the
LB_CFG_SYSTEM (offset 78
16
, BAR 0) with the value A05F
16
.
• 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 5c
16
).
• Convert you lower 24-bit address to a word aligned value.
• Write/Read data using Local-to-PCI Aperture 0.