AT89S52-33AC ATMEL Corporation, AT89S52-33AC Datasheet - Page 17

• Manufacturer Part Number: AT89S52-33AC
• Description: 8-bit Microcontroller with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

frequency should be less than 1/16 of the crystal fre-
quency. With a 33 MHz oscillator clock, the maximum SCK
frequency is 2 MHz.
Serial Programming Algorithm
To program and verify the AT89S52 in the serial program-
ming mode, the following sequence is recommended:
1. Power-up sequence:
2. Enable serial programming by sending the Pro-
3. The Code array is programmed one byte at a time
Apply power between VCC and GND pins.
Set RST pin to “H”.
If a crystal is not connected across pins XTAL1 and
XTAL2, apply a 3 MHz to 33 MHz clock to XTAL1 pin
and wait for at least 10 milliseconds.
gramming Enable serial instruction to pin
MOSI/P1.5. The frequency of the shift clock sup-
plied at pin SCK/P1.7 needs to be less than the
CPU clock at XTAL1 divided by 16.
by supplying the address and data together with the
4. Any memory location can be verified by using the
5. At the end of a programming session, RST can be
Power-off sequence (if needed):
Data Polling: The Data Polling feature is also available in
the serial mode. In this mode, during a write cycle an
attempted read of the last byte written will result in the com-
plement of the MSB of the serial output byte on MISO.
Serial Programming Instruction Set
The Instruction Set for Serial Programming follows a 4-byte
protocol and is shown in Table 10.
appropriate Write instruction. The write cycle is self-
timed and typically takes less than 1 ms at 5V.
Read instruction which returns the content at the
selected address at serial output MISO/P1.6.
set low to commence normal device operation.
Set XTAL1 to “L” (if a crystal is not used).
Set RST to “L”.
Turn V
CC
power off.
17