ADUC842BCP AD [Analog Devices], ADUC842BCP Datasheet - Page 10

• Manufacturer Part Number: ADUC842BCP
• Description: 12- Bit ADCs and DACs with Embedded Hi-Speed 62KB FLASH MCU
• Manufacturer: AD [Analog Devices]

ADuC842
INTRODUCTION
The ADuC842 is a 16MIPs 8052 core upgrade to the
ADuC832. It has all the same features as the ADuC832
but the standard 12-cycle 8052 core has been replaced with
a 16MIPs single cycle core.
Since the ADuC842 and ADuC832 share the same feature
set only the differneces bettween the two chips are docu-
mented here. For full documentation on the ADuC832
please consult the datasheet available at
http://www.analog.com/microconverter
8052 Instruction Set
The following pages document the number of clock cycles
required for each instruction. Most instructions are ex-
ecuted in one or two clock cycles resulting in a 16MIPs
peak peformance when operating at PLLCON = 00H.
Timer Operation
Timers on a standard 8052 increment by one with each
machine cycle. On the ADuC842 one machine cycle is
equal to one clock cycle hence the timers will increment at
the same rate as the core clock.
ALE
The output on the ALE pin on the ADuC832 was a clock
at 1/6th of the core operating frequency. On the ADuC842
the ALE pin operates as follows.
For a single machine cycle instruction: ALE is high for the
first half of the machine cycle and low for the second half.
The ALE output is at the core operating frequency.
For a two or more machine cycle instruction: ALE is high
for the first half of the first machine cycle and then low for
the rest of the machine cycles.
External Memory Access
There is no support for external program memory access
on the ADuC842. When accessing external RAM the
EWAIT register may need to be programmed in order to
give extra machine cycles to MOVX commands. This is to
account for differing external RAM access speeds.
Baud Rate Generation
There is an addition divide by two in the fractional divider
of the ADuC842 this means that any values calculated for
T3CON for the ADuC832 need to be incremented by one
in order to give the same baud rate on the ADuC842.
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