cx28560 Mindspeed Technologies, cx28560 Datasheet - Page 70

• Manufacturer Part Number: cx28560
• Description: Hdlc Controller
• Manufacturer: Mindspeed Technologies

Expansion Bus (EBUS)
3.1.9
3-8
Arbitration
The HOLD and HLDA (Intel) or BR* and BG* (Motorola) signal lines are used by
the CX28560 to arbitrate for the EBUS.
For Intel-style interfaces, the arbitration protocol is as follows (see Figure 9-8, EBUS
Write/Read Cycle, Intel-Style).
For Motorola-style interfaces, the arbitration protocol is as follows (refer to Figure 9-
9, EBUS Write/Read Cycle, Motorola-Style).
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The CX28560 three-states EAD[31:0], EBE*[3:0]. WR*, RD*, and ALE*.
The CX28560 requires EBUS access and asserts HOLD.
The CX28560 checks for HLDA assertion by bus arbiter.
If HLDA is found to be deasserted, the CX28560 waits for the HLDA signal to
become asserted before continuing the EBUS operation.
If HLDA is found to be asserted, the CX28560 continues with the EBUS
access as it has control of the EBUS.
The CX28560 drives EAD[31:0], EBE*[3:0], WR*, RD*, and ALE*.
The CX28560 completes EBUS access and deasserts HOLD.
Bus arbiter deasserts HLDA shortly thereafter.
The CX28560 three-states EAD[31:0], EBE*[3:0]. WR*, RD*, and ALE*.
The CX28560 three-states EAD[31:0], EBE*[3:0]. R/WR*, DS*, and AS*.
The CX28560 requires EBUS access and asserts BR*.
The CX28560 checks for BG* assertion by bus arbiter.
If BG* is found to be deasserted, the CX28560 waits for the BG* signal to
become asserted before continuing the EBUS operation.
If BG* is found to be asserted, the CX28560 continues with the EBUS access
as it has control of the EBUS.
If BGACK* is not asserted, the CX28560 assumes control of the EBUS by
asserting BGACK*.
The CX28560 drives EAD[31:0], EBE*[3:0], R/WR*, DS*, AS*.
Shortly after the EBUS cycle is started, the CX28560 deasserts BR*.
Bus arbiter deasserts BG* shortly thereafter.
The CX28560 completes EBUS cycle.
The CX28560 deasserts BGACK*.
The CX28560 three-states EAD[31:0], EBE*[3:0]. R/WR*, DS*, and AS*.
Mindspeed Technologies™
Advance Information
CX28560 Data Sheet
28560-DSH-001-B