pxb4340e Infineon Technologies Corporation, pxb4340e Datasheet - Page 47

• Manufacturer Part Number: pxb4340e
• Description: Atm Oam Processor Aop
• Manufacturer: Infineon Technologies Corporation

The microprocessor can not access these RAMs directly, but uses a transfer register set. It
consists of three blocks:
• read register block
• write register block
• mask register block.
In addition an address register specifying the entry to be accessed and a command register to
specify the RAM and to start the transfer are defined. The PXB 4340 AOP uses one single
access type, the read-modify-write transfer, where the old data is transferred from the specified
RAM entry to the Read Transfer Registers and the contents of the Write Transfer Registers are
written to the RAM entry for those bits which are unmasked.
In addition to the read-modify-write access executed upon microprocessor command for a single
entry, there are two other access types to the external RAM (figure 30):
• the access initiated by the passing ATM cell
• the SCAN access for OAM and/or DMA.
Data Sheet
internal or external RAM
Address = k
RAM entry n
RAM entry 0
RAM entry k
write
write
transfer
command
M
M
U
X
U
X
select
select
2-47
Read Transfer
Registers
CMR Register
Address Register
Mask
Registers
Write Transfer
Registers
Address
Data
—3
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