Hardware Interface 8
Synchronous Intel Mode
In this mode Intel CPUs like 80C51/52/32 and compatible processor series
from several manufacturers can be used.
Synchronous bus timing without evaluation of the XREADY signal
8-bit multiplexed bus: ADB7..0
The lower address bits AB7..0 are stored with the ALE signal in an in-
ternal address latch.
The internal CS decoder is activated. VPC3+C generates its own CS
signal from the address lines AB10..3. The VPC3+C selects the
relevant address window from the AB2..0 signals.
A11 from the microcontroller must be connected to XCS (pin 1) in 4K
Byte mode as this is the additional address bus signal in this mode. In
2K Byte mode this pin is not used and should be pulled to VDD.
Asynchronous Intel Mode
In this mode various 16-/8-bit microcontroller series like Intel’s x86,
Siemens 80C16x or compatible series from other manufacturers can be
used.
Asynchronous bus timing with evaluation of the XREADY signal
8-bit non-multiplexed bus: DB7..0, AB10..0 (AB11..0 in 4K Byte mode)
The internal VPC3+C address decoder is disabled, the XCS input is
used instead.
External address decoding is always necessary.
External chip select logic is necessary if not present in the microcon-
troller
A11 from the microcontroller must be connected to ALE/AS (pin 24) in
4K Byte mode as this is the additional address bus signal in this mode.
In 2K Byte mode this pin is not used and should be pulled to GND.
Asynchronous Motorola Mode
Motorola microcontrollers like the HC16 and HC916 can be used in this
mode. When using HC11 types with a multiplexed bus the address signals
AB7..0 must be generated from the DB7..0 signals externally.
Asynchronous bus timing with evaluation of the XREADY signal
8-bit non-multiplexed bus: DB7..0, (AB11..0 in 4K Byte mode)
The internal VPC3+C address decoder is disabled, the XCS input is
used instead.
Chip select logic is available and programmable in all microcontrollers
mentioned above.
AB11 must be connected to XWR/E_CLOCK (pin 2) in 4K Byte mode
as this is the additional address bus signal in this mode. In 2K Byte
mode this pin is not used and should be pulled to GND.
VPC3+C User Manual
Revision 1.03 71
Copyright © profichip GmbH 2004-2006
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