CCU3000 Datasheet, PDF (12/77 Pages) Micronas – Central Control Unit

CCU 3000, CCU 3000-I
CCU 3001, CCU 3001-I
XTAL2
XTAL1
CLK
IR
in
D
clr ^Q
D
Q
RDY
Φ2 in
CCU
3000,
CCU
3001
EMU
Version
A0
A15
D0
D7
clr
OR
Counter
2¹
en
A0 ...A15
D0 ...D7
ROM/RAM
Fig. 2–12: Using an external CPU
NMI
Ext.
CPU
or
Emul.
A0
A15
D0
D7
2.12. IM Bus Interface
The IM bus has been improved in its characteristics for
the CCU 3000, CCU 3001. In comparison to the inter-
face of the CCU 2000 series it differs in:
– multimaster ability
– 3 slave registers (8 bit wide)
– higher speed possible
The multimaster ability permits the use of several CCUs
on the same IM bus without impeding each other. Spe-
cially in add-on systems or systems with need of high
computing power and/or I/O requirements, this offers
great advantages. If several CCUs are admitted in a sys-
tem, it must be ascertained that these can communicate
with each other. A slave IM bus interface has been in-
stalled for this purpose. Parallel to the lines of the mas-
ter, three completely independent receiver registers
have been installed. All of these are constantly alert,
whether the master itself is active or not. As all CCUs
have the same IM bus addresses for these registers, the
contents of these registers (that is, for all CCUs that are
12
in the system) will be the same. The handshake
amongst these is realized in software, and one register
each is reserved for the device address, the request and
the data to be transported. The data rate can now be ad-
justed per software. It is possible to attain 1 MBit/s, if the
bus participants in question are devised to support this
rate. Also the actual realization of the bus can forbid
such a high data rate. The IM bus interface needs exter-
nal pull-up resistors.
In the I/O-page the IM bus interface reserves 8 bytes:
3 bytes
1 byte
2 bytes
1 byte
read:
slave receiving registers (read)
master address (write)
master data register (read/write)
control register (read/write)
bit 0 0... IM bus master ready
1... IM bus master busy
bit 1 1 Byte received in slave register 1
(may generate interrupt)
bit 2 IM-bus 1 control and status
(may generate interrupt)
bit 3 Word 3 Received (may generate
interrupt)
MICRONAS INTERMETALL