AT89S8252-16AA ATMEL Corporation, AT89S8252-16AA Datasheet - Page 20

• Manufacturer Part Number: AT89S8252-16AA
• Description: 8-Bit Microcontroller with 8K Bytes Flash
• Manufacturer: ATMEL Corporation

Serial Programming Algorithm
To program and verify the AT89S8252 in the serial pro-
gramming mode, the following sequence is recommended:
1. Power-up sequence:
2. Enable serial programming by sending the Program-
3. The Code or Data array is programmed one byte at a
Instruction Set
Notes:
4-124
Instruction
Programming Enable
Chip Erase
Read Code Memory
Write Code Memory
Read Data Memory
Write Data Memory
Write Lock Bits
Apply power between V
Set RST pin to “H”.
If a crystal is not connected across pins XTAL1 and
XTAL2, apply a 3 MHz to 24 MHz clock to XTAL1 pin
and wait for at least 10 milliseconds.
ming Enable serial instruction to pin MOSI/P1.5. The
frequency of the shift clock supplied at pin SCK/P1.7
needs to be less than the CPU clock at XTAL1 divided
by 40.
time by supplying the address and data together with
the appropriate Write instruction. The selected memory
location is first automatically erased before new data is
1. DATA polling is used to indicate the end of a write cycle which typically takes less than 2.5 ms at 5V.
2. “aaaaa” = high order address.
3. “x” = don’t care.
AT89S8252
aaaa a001
aaaa a010
1010 1100
1010 1100
00aa a101
00aa a110
1010 1100
CC
Byte 1
and GND pins.
Input Format
0101 0011
xxxx x100
low addr
low addr
low addr
low addr
Byte 2
x x111
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
Byte 3
data in
data in
4. Any memory location can be verified by using the Read
5. At the end of a programming session, RST can be set
Power-off sequence (if needed):
Serial Programming Instruction
The Instruction Set for Serial Programming follows a 3-byte
protocol and is shown in the following table:
Operation
Enable serial programming interface after RST goes high.
Chip erase both 8K & 2K memory arrays.
Read data from Code memory array at the selected address.
The 5 MSBs of the first byte are the high order address bits.
The low order address bits are in the second byte. Data are
available at pin MISO during the third byte.
Write data to Code memory location at selected address. The
address bits are the 5 MSBs of the first byte together with the
second byte.
Read data from Data memory array at selected address. Data
are available at pin MISO during the third byte.
Write data to Data memory location at selected address.
Write lock bits.
Set LB1, LB2 or LB3 = “0” to program lock bits.
Set XTAL1 to “L” (if a crystal is not used).
Set RST to “L”.
Turn V
written. The write cycle is self-timed and typically takes
less than 2.5 ms at 5V.
instruction which returns the content at the selected
address at serial output MISO/P1.6.
low to commence normal operation.
CC
power off.