AT89S4051 Atmel Corporation, AT89S4051 Datasheet - Page 29

• Manufacturer Part Number: AT89S4051
• Manufacturer: Atmel Corporation

Specifications of AT89S4051

• Flash (kbytes): 4 Kbytes
• Max. Operating Frequency: 24 MHz
• Cpu: 8051-12C
• Max I/o Pins: 15
• Uart: 1
• Sram (kbytes): 0.25
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 2
• Isp: SPI

31. Write Lock Bits/User Fuses
32. Read Lock Bits/User Fuses
3390E–MICRO–6/08
Function:
Usage:
1) Apply “1111” TestCode to P3.7, P3.5, P3.4, P3.3.
Figure 31-1. Write Lock Bits/User Fuses
Function:
Usage:
Figure 32-1. Read Lock Bits/User Fuses
1. Program Lock Bits 1 and 2.
2. Program user fuses.
3. Drive Port P1 with fuse data, bits [7:4] for fuses and bits [1:0] for lock bits.
4. Pulse P3.2 low for 1 µs.
5. Wait 4 ms, monitor P3.1, or poll data.
1. Read status of Lock Bits 1 and 2.
2. Read status of user fuses.
1. Apply “0011” TestCode to P3.7, P3.5, P3.4, P3.3.
2. Read fuse data from Port P1, bits [7:4] for fuses and bits [1:0] for lock bits.
P3.3. - P3.7
RDY/BSY
RDY/BSY
P3.3 - P3.7
P1.0 - P1.7
P1.0 - P1.7
XTAL1
XTAL1
P3.2
P3.2
High Z
High Z
DATA
1111
DOUT
0011
AT89S2051/S4051
High Z
High Z
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