Specifications

164
3706C–MICRO–2/11
AT89LP3240/6440
25.7 User Configuration Fuses
The AT89LP3240/6440 includes 11 user fuses for configuration of the device. Each fuse is
accessed at a separate address in the User Fuse Row as listed in Table 25-5. Fuses are cleared
by programming 00h to their locations. Programming FFh to a fuse location will cause that fuse
to maintain its previous state. To set a fuse (
set to FFh) the fuse row must be erased and then
reprogrammed using the Fuse Write with Auto-erase command. The default state for all fuses is
FFh.
Notes: 1. The default state for all fuses is FFh.
2. Changes to these fuses will only take effect after a device POR.
3. Changes to these fuses will only take effect after the ISP session terminates by bringing RST
high.
Table 25-5. User Configuration Fuse Definitions
Address Fuse Name Description
00 – 01h Clock Source – CS[0:1]
(2)
Selects source for the system clock:
CS1CS0 Selected Source
00h 00h High Speed Crystal Oscillator (XTAL)
00h FFh Low Speed Crystal Oscillator (XTAL)
FFh 00h External Clock on XTAL1 (XCLK)
FFh FFh Internal RC Oscillator (IRC)
02 – 03h Start-up Time – SUT[0:1]
Selects time-out delay for the POR/BOD/PWD wake-up period:
SUT1 SUT0 Selected Time-ou t
00h 00h 1 ms (XTAL); 16 µs (XCLK/IRC)
00h FFh 2 ms (XTAL); 512 µs (XCLK/IRC)
FFh 00h 4 ms (XTAL); 1 ms (XCLK/IRC)
FFh FFh 16 ms
(XTAL); 4 ms (XCLK/IRC)
04h Reset Pin Enable
(3)
FFh: RST pin functions as reset
00h: RST pin functions as general purpose I/O
05h Brown-Out Detector Enable
FFh: Brown-out Detector Enabled
00h: Brown-out Detector Disabled
06h On-Chip Debug Enable
FFh: On-Chip Debug Disabled
00h: On-Chip Debug Enabled
07h ISP Enable
(3)
FFh: In-System Programming Enabled
00h: In-System Programming Disabled (Enabled at POR only)
08HUser Signature Programming
FFh: Programming of User Signature Disabled
00h: Programming of User Signature Enabled
09H Tristate Ports
FFh: I/O Ports start in input-only mode (tristated) after reset
00h: I/O Ports start in quasi-bidirectional mode after reset
0AH OCD Interface Select
FFh: Fast two-wire interface
00h: Do not use
0BH In-Application Programming
FFh: In-Application Programming Disabled
00h: In-Application Programming Enabled