Tait TB9100 Service Manual

48 Network Circuitry TB9100 Reciter Service Manual
© Tait Electronics Limited January 2006
MPC Bus Cycles
The MPC is capable of arbitrating with other external bus servers for control
of the address and data buses using the Bus Request (BR
), Bus Grant (BG)
and Bus Busy (BB
) pins. External bus servers are not used in the ASIF
design, so the MPC is configured (see “MPC Configuration” on page 45)
for internal arbitration, and the bus arbitration pins are pulled up to their
inactive high state.
Assuming that the MPC has obtained ownership of the bus, it starts a bus
cycle by outputting the address and the transfer attributes detailed in
Tabl e 5 .6. The transfer start signal (TS
) is asserted to indicate the start of a
bus cycle.
Except for the RD/WR
line, none of the above transfer attributes are used
in the ASIF external memory logic, but they may be used internally by the
memory controllers (see “Memory Controllers” on page 49) to determine
the cycle type. Some are available on test points to facilitate hardware and
program debugging.
When the memory or peripheral devices has output/input the data to/from
the bus, it tells the MPC to terminate the bus cycle by asserting the transfer
acknowledge signal (TA
). For devices that do not have a suitable transfer
acknowledge signal, this can be provided internally by the relevant memory
controller (see “Memory Controllers” on page 49). The sequence of
operations for a single (ie. non-burst) bus write cycle is shown in Figure 5.4.
Table 5.6 Bus Cycle Transfer Attributes
Transfer Attribute Function
RD/WR Read/write cycle
AT[0..3] Address type modifier 0: Core/CPM access
Address type modifier 1: User/supervisor access
Address type modifier 2: Instruction/Data
Address type modifier 3: Reservation/Program Trace
TSIZ[0..1] Transfer size (see Ta ble 5. 5)
STS
Special transfer start: used for debugging purposes
BURST
Burst transfer: indicates memory cycle is a burst operation
(see “SDRAM Burst Cycles” on page 64)
BDIP
Burst data in progress: indicates another data transfer is
expected

Tait TB9100 Specifications

General

Brand	Tait
Model	TB9100
Category	Accessories
Language	English