MT90840AP Zarlink, MT90840AP Datasheet - Page 24

• Manufacturer Part Number: MT90840AP
• Description: Switch Fabric 512 x 2430/512 x 512/2.373K x 2.373K 5V 84-Pin PLCC Tube
• Manufacturer: Zarlink

Specifications of MT90840AP

• Package: 84PLCC
• Number Of Ports: 16
• Fabric Size: 512 x 2430|512 x 512|2.373K x 2.373K
• Switch Core: Non-Blocking
• Port Speed: 8.192|4.096|2.048 Mbps
• Operating Supply Voltage: 5 V

2.048 Mbps Add/Drop Mode
The 2.048 Mbps Add/Drop mode has 16 serial input/output streams, and 32 channels per stream. Therefore 4 bits
are used to address the 16 streams, and 5 bits are used to address the 32 channels. Figure 12a shows how the
Transmit Path Data Memory is read in this mode. Each of the 512 possible input channels is mapped to an address
in the TPDM. CPU reads require the 2 LSBs of the CAR Register, and the 7 LSBs of the address bus. The source-
channel address-value written in the TPCM requires 9 bits. In this mode the TPDM reads all 512 serial channels as
inputs. When a specific channel is driven by the MT90840 as an output, the output data is also copied back into the
TPDM.
Figure 12b shows how the Receive Path Connection Memory is addressed by the CPU in 2.048 Mbps Add/Drop
mode. Each of the 512 possible output channels has a control-address in the RPCM. CPU accesses require the 2
LSBs of the CAR Register, and the 7 LSBs of the address bus. When the DC bit or the OE bit at a specific control-
address is LOW, no data is driven out for that channel, and the input data at the pin is written to the TPDM.
Figure 12a - 2.048 Mbps Add/Drop Mode TPDM Addressing
Serial I/O
Channel
STo7 (STi15), Ch30
STo7 (STi15), Ch31
STo0 (STi8), Ch0
STo0 (STi8), Ch1
STi7, Ch30
STi7, Ch31
STi0, Ch0
STi0, Ch1
.
.
.
.
Zarlink Semiconductor Inc.
MT90840
TPDM
Address
101H
000H
001H
0FEH
0FFH
100H
1FEH
1FFH
24
CPU Port Addressing:
CAR
TPCM Contents:
Stream
Bits 8:5 select one of 16 streams.
Bits 4:0 select one of 32 channels per
stream.
1 0
8 7 6 5
Stream
Address Bus
6 5 4 3 2 1 0
Channel
4 3 2 1 0
Channel
Data Sheet