PEB2085 SIEMENS [Siemens Semiconductor Group], PEB2085 Datasheet - Page 160

• Manufacturer Part Number: PEB2085
• Description: ISDN SubscribernAccess Controller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

3.1
The ISAC-S is programmed via an 8-bit parallel microcontroller interface. Easy and fast
microprocessor access is provided by 8-bit address decoding on the chip. Depending on the
chip package (P-DIP-40, P-LCC-44 or M-QFP-64) either one or three types of P buses are
provided:
P-DIP-40 package:
The ISAC-S microcontroller interface is of the Siemens/Intel multiplexed address/data bus
type with control signals CS, WR, RD, ALE.
P-LCC-44/P-MQFP-64 package:
The ISAC-S microcontroller interface can be selected to be either of the
(1) – Motorola type with control signals CS, R/W, DS
(2) – Siemens/Intel non-multiplexed bus type with control signals CS, WR, RD
(3) – or of the Siemens/Intel multiplexed address/data bus type with control
The selection is performed via pin ALE as follows:
ALE tied to V
ALE tied to V
Edge on ALE
The occurrence of an edge on ALE, either positive or negative, at any time during the operation
immediately selects interface type (3). A return to one of the other interface types is possible
only if a hardware reset is issued.
Notes: 1) If the multiplexed address/data bus type (3) is selected, the unused address pins
Semiconductor Group
signals CS, WR, RD, ALE.
2) If the non-multiplexed bus types (1) or (2) are selected, the serial interfaces SLD
Microprocessor Interface Operation
A0-A5 are internally not evaluated and may thus be left open. It is however
recommended to tie the unused input pins to a defined voltage level (e.g. V
V
and SSI can no longer be used since pin 5 (SDAR)/A2 and pin 10 (SIP/EAW)/A5
now have the function of address pins. These P bus types are therefore primarily
intended to be used in IOM-2 modes (ADF2:IMS=1).
If however the PEB 2086 P-MQFP-64 package is used, the demultiplexed micro-
processor interface is also available in IOM-1 mode.
DD
SS
DD
).
(1)
(2)
(3).
160
Operational Description
SS
or