Rainbow Electronics AT89C5131 User Manual
Page 63
63
AT89C5131
4136A–USB–03/03
Reset Value = 0X0X 1100b
Not bit addressable
Table 49. AUXR Register
AUXR - Auxiliary Register (8Eh)
7
6
5
4
3
2
1
0
DPU
-
M0
-
XRS1
XRS0
EXTRAM
AO
Bit
Number
Bit
Mnemonic
Description
7
DPU
Disable Weak Pull Up
Cleared to enabled weak pull up on standard Ports.
Set to disable weak pull up on standard Ports.
6
-
Reserved
The value read from this bit is indeterminate. Do not set this bit
5
M0
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.
4
-
Reserved
The value read from this bit is indeterminate. Do not set this bit
3
XRS1
XRAM Size
XRS1
XRS0
XRAM size
0
0
256 bytes
0
1
512 bytes
1
0
768 bytes
1
1
1024 bytes (default)
2
XRS0
1
EXTRAM
EXTRAM bit
Cleared to access internal XRAM using MOVX at Ri at DPTR.
Set to access external memory.
0
AO
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.