Rainbow Electronics AT89LP216 - Manual (Page 71)

71
3621A–MICRO–6/06
AT89LP216 [Preliminary]
23.7 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 23-5 . 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.
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 23-5. User Configuration Fuse Definitions
Address Fuse Name Description
00 – 01h Clock Source – CS[0:1] (2)
Selects source for the system clock:
CS1 CS0 Selected Source
00h 00h Crystal Oscillator (XTAL)
00h FFh Reserved
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-out
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.
10H User Signature Programming
FFh: Programming of User Signature Disabled
00h: Programming of User Signature Enabled
11H 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
12H OCD Interface Select
FFh: Normal two-wire interface
00h: Fast two-wire interface