ORT8850H AGERE [Agere Systems], ORT8850H Datasheet - Page 39

• Manufacturer Part Number: ORT8850H
• Description: Field-Programmable System Chip (FPSC) Eight-Channel x 850 Mbits/s Backplane Transceiver
• Manufacturer: AGERE [Agere Systems]

Data Sheet
August 2001
Agere Systems Inc.
Memory Map
Table 10. Structural Register Elements
Registers Access and General Description
The memory map comprises three address blocks:
All registers are write-protected by the lock register, except for the scratch pad register. The lock register is a 16-bit
read/write register. Write access is given to registers only when the key value 0x0580 is present in the lock register.
An error flag will be set upon detecting a write access when write permission is denied. The default value is
0x0000.
After powerup reset or soft reset, unused register bits will be read as zeros. Unused address locations are also
read as zeros. Write-only register bits will be read as zeros. The detailed information on register access and func-
tion are described on the tables, memory map, and memory map bit description.
A memory map is included in Table 11, followed by detailed descriptions in Table 11. These tables list only the
memory map for the core registers of the ORT8850 device. The remaining FPGA registers can be found in the
Series 4 data sheet.
Element
Generic register block: ID, revision, scratch pad, lock, FIFO alignment, and reset registers.
Device register block: control and status bits, common to the four channels in each of the two quad interfaces.
Channel register blocks: each of the four channels in both quads have an address block. The four address
blocks in both quads have the same structure, with a constant address offset between channel register blocks.
iareg
isreg
preg
ereg
sreg
creg
Interrupt Enable
Interrupt Status
Interrupt Alarm
Register
Register
Register
Register
Register
Register
Register
Control
Status
Pulse
(continued)
A status register is read only, and, as the name implies, is used to convey the status
information of a particular element or function of the ORT8850 core. The reset value of
an sreg is really the reset value of the particular element or function that is being read.
In some cases, an sreg is really a fixed value; an example of which is the fixed ID and
revision registers.
A control register is read and writable memory element inside core control. The value of
a creg will always be the value written to it. Events inside the ORT8850 core cannot
affect creg value. The only exception is a soft reset, in which case the creg will return to
its default value.
Each element, or bit, of a pulse register is a control or event signal that is asserted and
then deasserted when a value of one is written to it. This means that each bit is always
of value 0 until it is written to, upon which it is pulsed to the value of one and then
returned to a value of 0. A pulse register will always have a read value of 0.
Each bit of an interrupt alarm register is an event latch. When a particular event is pro-
duced in the ORT8850 core, its occurrence is latched by its associated iareg bit. To
clear a particular iareg bit, a value of one must be written to it. In the ORT8850 core, all
isreg reset values are 0.
Each bit of an interrupt status register is physically the logical-OR function. It is a con-
solidation of lower-level interrupt alarms and/or isreg bits from other registers. A direct
result of the fact that each bit of the isreg is a logical-OR function means that it will have
a read value of one if any of the consolidation signals are of value one, and will be of
value 0 if and only if all consolidation signals are of value 0. In the ORT8850 core, all
isreg default values are 0.
Each bit of a status register or alarm register has an associated enable bit. If this bit is
set to value one, then the event is allowed to propagate to the next higher level of con-
solidation. If this bit is set to zero, then the associated iareg or isreg bit can still be
asserted but an alarm will not propagate to the next higher level. An interrupt enable bit
is an interrupt mask bit when it is set to value 0.
Eight-Channel x 850 Mbits/s Backplane Transceiver
Description
ORCA ORT8850 FPSC
39