Sundance SMT130 v.1.0 - Manual (Page 25)

User Manual (QCF42); Version 3.0, 8/11/00; © Sundance Multiprocessor Technology Ltd. 1999
12 Global/Local Bus Transfers, DSP <-> PCI.
The traditional global bus interface on C6x DSP modules interfaces to the SMT130
via a local bus. This allows Global bus transfers on the DSP to be converted into
local bus accesses. This allows direct DSP accesses to the PCI Bridge chip.
The resources in the PCI Bridge chip are illustrated in the figure below.
PCI Bridge Device
MailBox
Read/Write
Interrupt Control
Local To PCI Bus
Apperture Control
LOCAL <-> PCI
Apperture 0
16MB Address
Space
DSP Global
Bus Access
Arbitration
Unit
Local Bus
Figure 3 : Local Bus to DSP Connectivity
12.1 Mailbox Accesses
The mailbox registers can be used if small amounts of data or commands between
the PCI bus and the DSP, via the local bus, need to be transferred. Rather than
sending Comport data, and therefore require the DSP to be checking its Comport for
commands, a mailbox write by the PCI bus can be initialized to generate an interrupt
on an DSP IIOF line indicating, to the DSP, that data is available. The PCI Bridge
device provides 16 8-bit mailbox registers, which may be used to transmit and
receive data between the DSP and Host.