SC1100 Datasheet, PDF (242/348 Pages) National Semiconductor (TI) – Geode™ Information Appliance On a Chip

Core Logic Module (Continued)
Table 5-38. F3BAR0+Memory Offset: XpressAUDIO Configuration Registers (Continued)
Bit Description
Offset 31h
Audio Bus Master 2 SMI Status Register (RC)
Audio Bus Master 2: Output to codec; 16-Bit; Slot 5.
Reset Value: 00h
7:2 Reserved
1
Bus Master Error. Indicates if hardware encountered a second EOP before software has cleared the first.
0: No.
1: Yes.
If hardware encounters a second EOP (end of page) before software has cleared the first, it causes the bus master to pause
until this register is read to clear the error.
0
End of Page. Indicates if the Bus master transferred data which is marked by the EOP bit in the PRD table (bit 30).
0: No.
1: Yes.
Offset 32h-33h
Not Used
Reset Value: 00h
Offset 34h-37h
Audio Bus Master 2 PRD Table Address (R/W)
Audio Bus Master 2: Output to codec; 16-Bit; Slot 5.
Reset Value: 00000000h
31:2 Pointer to the Physical Region Descriptor Table. This bit field contains a PRD table pointer for Audio Bus Master 2.
When written, this field points to the first entry in a PRD table. Once Audio Bus Master 2 is enabled (Command Register bit
0 = 1), it loads the pointer and updates this register (by adding 08h) so that it points to the next PRD.
When read, this register points to the next PRD.
1:0 Reserved. Must be set to 0.
Note: The Physical Region Descriptor (PRD) table consists of one or more entries - each describing a memory region to or from
which data is to be transferred. Each entry consists of two DWORDs.
DWORD 0:
DWORD 1:
[31:0]
31
30
29
[28:16]
[15:0]
= Memory Region Physical Base Address
= End of Table Flag
= End of Page Flag
= Loop Flag (JMP)
= Reserved (0)
= Byte Count of the Region (Size)
Offset 38h
Audio Bus Master 3 Command Register (R/W)
Audio Bus Master 3: Input from codec; 16-Bit; Slot 5.
Reset Value: 00h
7:4 Reserved. Must be set to 0. Must return 0 on reads.
3
Read or Write Control. Sets the transfer direction of Audio Bus Master 3.
0: PCI reads are performed.
1: PCI writes are performed.
This bit must be set to 1 (write) and should not be changed when the bus master is active.
2:1 Reserved. Must be set to 0. Must return 0 on reads.
0
Bus Master Control. Controls the state of the Audio Bus Master 3.
0: Disable.
1: Enable.
Setting this bit to 1 enables the bus master to begin data transfers. When writing 0 to this bit, the bus master must be either
paused or have reached EOT. Writing 0 to this bit while the bus master is operating results in unpredictable behavior (and
may crash the bus master state machine). The only recovery from this condition is a PCI reset.
www.national.com
242
Revision 1.1