Nortel Networks MSC8101 ADS BCSR0 Description, BCSR0 Board Control / Status Register, Hostrqac

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

Functional Description

•Buffers Enable/Disable.

•Device Reset.

4)Host Interface which includes:

•Buffers Enable/Disable

•Host Acknowledge Enable

5)ATM Port Control which includes:

•Transceiver Enable / Disable

•Device Reset.

6)Fast Ethernet Port Control which includes:

•Transceiver Initial Enable

•Device Reset

7)RS232 port 1 Enable / Disable.

8)RS232 port 2 Enable / Disable.

9)Flash Size / Delay Identification.

10)External (off-board) tools Support which include:

•Tool Identification

•Tool Revision

•Tool Status Information

11)S/W Option Identification.

12)ADS Revision code.

Since part of the ADS’s modules are controlled by the BCSR and since they may be disabled in favor of external hardware, the enable signals for these modules are presented at the CPM expan- sion connectors, so that off- board hardware may be mutually-exclusive enabled with on-board modules.

For reason to achieve maximum SW compatibility with Voyager ADS the usable control/status bits will be populated at the corresponding addresses.

5•11•1 BCSR0 - Board Control / Status Register 0

The BCSR0 serves as a control register on the ADS. Although it resides only over D(0:7) lines of the PPC data bus, it is accessed as a word at offset 0 from BCSR base address. It may be read or written at any time. BCSR0 gets its defaults upon Power-On reset. BCSR0 fields are described in TABLE 5-9. "BCSR0 Description" below:

TABLE 5-9. BCSR0 Description

BIT	MNEMONIC	Function	PON	ATT.
			DEF
0	HOSTCSP	Host Chip Select Polarity. Defines the chip-select polarity for Host I/F, for	0	R,W
		both chip-select inputs HCS1 and HCS2. When low chip-selects have
		negative polarity, otherwise - positive.
1	HOSTRQAC	Host Request or Acknowledge Select. When Host I/F supports DMA	0	R,W
		acknowledge, this bit should be set low and high for double host request
		mode. This bit allows to change direction of external buffer.

MOTOROLA MSC8101ADS RevB User’s Manual 55

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