AT89LP216_09 Datasheet, PDF (71/98 Pages) ATMEL Corporation – 8-bit Microcontroller with 2K Bytes Flash

AT89LP216
24.7
User Configuration Fuses
The AT89LP216 includes 19 user fuses for configuration of the device. Each fuse is accessed at
a separate address in the User Fuse Row as listed in Table 24-5. Fuses are cleared by program-
ming 00h to their locations. Programming FFh to 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.
Table 24-5. User Configuration Fuse Definitions
Address Fuse Name
Description
Selects source for the system clock:
CS1
CS0
Selected Source
00 – 01h Clock Source – CS[0:1]⁽²⁾
00h
00h
Crystal Oscillator (XTAL)
00h
FFh
Reserved
FFh
00h
External Clock on XTAL1 (XCLK)
FFh
FFh
Internal RC Oscillator (IRC)
Selects time-out delay for the POR/BOD/PWD wake-up period:
SUT1
SUT0
Selected Time-out
02 – 03h
Start-up Time – SUT[0:1]
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)
08 – 0FH
RC Oscillator Frequency
Adjustment [0:7]
Adjusts the frequency of the internal RC oscillator. A copy of the 8MHz factory
setting is stored at location 0008h of the Atmel Signature.
10H
User Signature Programming
FFh: Programming of User Signature Disabled
00h: Programming of User Signature Enabled
11H
Tristate Ports⁽⁴⁾
FFh: I/O Ports start in input-only mode (tristated) after reset
00h: I/O Ports start in quasi-bidirectional mode after reset
12H
OCD Interface Select
FFh: Fast two-wire interface
00h: Do not use
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.
4. AIN0 (P1.0) and AIN1 (P1.1) always reset to input-only mode. SS (P1.4) always resets to quasi-bidirectional mode.
71
3621D–MICRO–10/09