
ADSP-2192M
–22–
REV. 0
In Sub-ISA mode, the ADSP-2192M’s PCI protocol is replaced 
with an ISA-like, asynchronous protocol controlled by the strobes 
IOR
, 
IOW,
 and 
AEN
. Access is possible only to the PCI Base 
Address 4 (BAR4) Registers (the InDirect Access Registers). 
The Sub-ISA Address Map is shown in 
Table 24
.
An active low 
RST
 input (to be derived from PCI 
RST
 and 
possible other sources) and an active-high IRQ interrupt output 
are available. Power Management is handled by the ADSP-
2192M inputs 
PDW1–0
/PME_EN and the ADSP-2192M 
output 
PMERQ
. 
PDW1–0
 should be the inversion of the PCI 
power state in the function’s PMCSR register. 
PDW1
 is con-
nected to AD21, and 
PDW0
 is connected to AD20.
Assertion of 
PDW1
 low signals a power-down interrupt to the 
DSP. Deassertion of 
PDW1
 high causes a wake-up of the DSP. 
The PME_EN output from the Combo Master should reflect the 
current PCI function PME_EN bit and should be connected to 
the ADSP-2192M AD20 pin. The PMI_EN bit should be set to 
enable interrupt and wake-up of the DSP upon any change of the 
PME_EN state. If PME_EN is turned off, the DSPs can wake 
up if necessary and then power themselves and the ADSP-2192M 
completely down (clocks stopped).
PCI Interface to DSP Memory
The PCI interface can directly access the DSP memory space 
using DMA transfers. The transactions can be either slave trans-
fers, in which the host initiates the transaction, or master 
transfers, in which the ADSP-2192M initiates the PCI transac-
tion. The registers that control PCI DMA transfers are accessible 
from both the DSP (on the Peripheral Device Control Bus) and 
the PCI Bus.
The PCI/Sub-ISA Bus uses the Peripheral Device Control 
Register Space which is distributed throughout the ADSP-
2192M and connected through the Peripheral Device Control 
Bus. The PCI bus can access these registers directly.
USB Interface to DSP Memory
The USB interface can directly access the DSP memory space 
using DMA transfers to memory locations specified by the USB 
endpoints. The registers that control USB endpoint DMA 
transfers are accessible from both the DSP (on the Peripheral 
Device Control Bus) and the USB Bus.
The Peripheral Device Control Register Space is distributed 
throughout the ADSP-2192M and connected through the 
Peripheral Device Control Bus. The USB Bus can access these 
registers directly.
AC’97 Codec Interface to DSP Memory
Transfers from AC’97 data to DSP memory are accomplished 
using DMA transfer through the DSP FIFOs. Each DSP has four 
FIFOs available for data transfers to/from the AC’97 Codec 
Interface. The registers that control FIFO DMA transfers are 
only accessible from within the DSP and are defined as part of 
the core register space.
Data FIFO Architecture
Each DSP core within the ADSP-2192M contains four FIFOs 
which provide a data communication path to the rest of the chip. 
Two of the FIFOs are input FIFOs, receiving data into the DSP. 
The other two FIFOs are transmit FIFOs, sending data from the 
DSP to the codec, AC’97 interface, or the other DSP. Each FIFO 
is eight words deep and sixteen bits wide. Interrupts to the DSP 
can be generated when some words have been received in the 
input FIFOs, or when some words are empty in the 
Transmit FIFOs.
The interface to the FIFOs on the DSP is simply a register 
interface to the Peripheral Interface bus. TX0, RX0, TX1, and 
RX1 are the primary FIFO registers in the DSP’s universal 
register map. The FIFOs can be used to generate interrupts to 
the DSP, based upon FIFO transactions, or they can initiate 
DMA requests.
When communicating with the AC’97 interface, the Connection 
Enable bits in the control register are set to 10. Bit 3 selects stereo 
or mono transfers to and from the AC’97 interface. Bits 7–4 
select the AC’97 slot associated with this FIFO. 
When stereo is selected, the slot identified and the next slot are 
both associated with the FIFO. Typically, stereo is selected for 
left and right data, and both left and right must be associated with 
the same external AC’97 codec and have their sample rates locked 
together. In this case, left and right data will alternate in the FIFO 
with the left data coming first.
If the FIFO is enabled for the AC’97 interface, and a valid request 
for data comes along that the FIFO cannot fulfill, the transmitter 
underflow bit is set, indicating that an invalid value was sent over 
the selected slot. Similarly, on the receive side, if the FIFO is full 
and another valid word is received, the Overflow bit is sent to 
indicate the loss of data.
Table 24. Sub-ISA Indirect Access Registers 
ISAA[3:1]
Name
Reset
Comments
0x0
0x1
0x2
0x3
0x5–0x4
Control Register Address
Reserved
Control Register Data
Reserved
DSP Memory Address
0x0000
0x0000
Address and direction control for register accesses
Data for register accesses
0x000000
Address and direction control for DSP memory 
accesses
Data for DSP memory accesses.
0x7–0x6
DSP Memory Data
0x000000