8051 Family

From miki
Revision as of 18:47, 25 August 2008 by Mip (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

The Intel 8051 is a single chip microcontroller which was developed by Intel in 1980 for use in embedded systems. It has become very popular in the 80s, but today many manufacturers propose enhanced versions that are 8051-compatible.

Architecture

Speed

Name Clock freq. clock / instr. cycle(*)
Standard 8051 12MHz
16MHz
20MHz
24MHz
12
NXP P89V66x
NXP P89CV51Rx2
0MHz..40MHz 12
20MHz 6
NXP P8xC660X2/661X2
NXP P87C51RX2
0MHz..33MHz 12
0MHz..30MHz 6
NXP LPC938 12MHz
18MHz
2

(*) # clock oscillation periods / instruction cycle.

Expanded RAM

Intel 8XC51RA series uses a trick called Expanded RAM to allow accessing 512 byte of on-chip RAM memory. See 8XC51RA/RB/RC Hardware Description for detailed information.

In summary, there are 4 RAM memory segments:

Lower 128 bytes of RAM 00h..7Fh DIRECT INDIRECT
Upper 128 bytes of RAM 80h..FFh INDIRECT
Special Function Registers (SFR) 80h..FFh DIRECT
256-byte expanded RAM (ERAM) 00h..FFh MOVX @R0
MOVX @R1
MOVX @DPTR
(EXTRAM=0)

Links

Intel

NXP

NXP (ex. Philips Semiconductors) offers a wide range of 8051-compatible controllers: