Expansion Bus Host Port Operation
8-31
Expansion Bus
Burst Write Transfer
The timing presented in Figure 8–20 can be referenced for a visual description
of the steps required to complete a burst write initiated by the C6202 and
throttled by the XWAIT and XRDY signals.
Figure 8–20. Write Transfer Initiated by the TMS320C6202 and Throttled by
XWAIT and XRDY (Internal Bus Arbiter Disabled)
1
2
3
4
5
6
7
8
9
10
11
12 13
14
15 16
17
18 19
XCLKIN (input)
XHOLD (output)
XHOLDA (input)
XAS (output)
XW/R (output)
XBLAST (output)
XBE[3:0] (output)
XD[31:0] (i/o)
XRDY (input)
XWAIT (output)
BE
AD
D1
D2
D3
D4
D5
D6
D7
D8
The step by step description of the events marked above the waveforms in
Figure 8–20 follows:
1) The DSP requests the expansion bus (XHOLD asserted).
2) The DSP waits for the XHOLDA signal to be asserted by the external arbi-
ter.
3) The external bus arbiter asserts the XHOLDA signal, the XAS, XW/R,
XBLAST, and XBE[3:0] signals become outputs, and the XRDY signal be-
comes an input.
4) Address phase: During this phase, the XAS is asserted and the address
is presented on the expansion bus.