at89c5131 ATMEL Corporation, at89c5131 Datasheet - Page 49

• Manufacturer Part Number: at89c5131
• Description: 8-bit Flash Microcontroller With Full Speed Usb Device At89c5131
• Manufacturer: ATMEL Corporation

48
AT89C5131
Table 46. AUXR Register
AUXR - Auxiliary Register (8Eh)
Reset Value = 0X0X 1100b
Not bit addressable
Number
DPU
Bit
7
6
5
4
3
2
1
0
7
Mnemonic
EXTRAM
XRS1
XRS0
DPU
Bit
AO
M0
6
-
-
-
Description
Disable Weak Pull Up
Cleared to enabled weak pull up on standard Ports.
Set to disable weak pull up on standard Ports.
Reserved
The value read from this bit is indeterminate. Do not set this bit
Pulse length
Cleared to stretch MOVX control: the RD and the WR pulse length is 6 clock
periods (default).
Set to stretch MOVX control: the RD and the WR pulse length is 30 clock
periods.
Reserved
The value read from this bit is indeterminate. Do not set this bit
ERAM Size
XRS1
0
0
1
1
EXTRAM bit
Cleared to access internal ERAM using MOVX at Ri at DPTR.
Set to access external memory.
ALE Output bit
Cleared, ALE is emitted at a constant rate of 1/6 the oscillator frequency (or
1/3 if X2 mode is used) (default).
Set, ALE is active only when a MOVX or MOVC instruction is used.
M0
5
XRS0
0
1
0
1
4
-
ERAM size
256 bytes
512 bytes
768 bytes
1024 bytes (default)
XRS1
3
XRS0
2
EXTRAM
1
4136C–USB–04/05
AO
0