Manual

60
AT89C5131
4136A–USB–03/03
Hardware Byte
Default value after erasing chip: FFh
Notes: 1. Only the 4 MSB bits can be access by software.
2. The 4 LSB bits can only be access by parallel mode.
Table 47. Hardware Byte
76543210
X2B BLJB OSCON1 OSCON0 - LB2 LB1 LB0
Bit Number
Bit
Mnemonic Description
7X2B
X2 Bit
Set this bit to start in standard mode
Clear this bit to start in X2 mode.
6BLJB
Bootloader Jump Bit
Set this bit to start the user’s application on next reset at address 0000h.
Cleared this bit to start the bootloader at address F400h (default).
5-4 OSCON1-0
Oscillator Control Bits
These two bits are used to control the oscillator in order to reduce
consumption.
OSCON1
OSCON0 Description
1 1 oscillator is configured to run from 0 to 32 MHz
1 0 oscillator is configured to run from 0 to 16 MHz
0 1 oscillator is configured to run from 0 to 8 MHz
0 0 this configuration shouldn’t be set
3-
Reserved
The value read from this bit is indeterminate.
2-0 LB2:0 Lock Bits