AT89LP6440-20AU Atmel, AT89LP6440-20AU Datasheet - Page 14

• Manufacturer Part Number: AT89LP6440-20AU
• Description: MCU 8051 64K FLASH ISP 44TQFP
• Manufacturer: Atmel
• Series: 89LPr

Specifications of AT89LP6440-20AU

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 38
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 8K x 8
• Ram Size: 4.25K x 8
• Voltage - Supply (vcc/vdd): 2.4 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Package: 44TQFP
• Device Core: 8051
• Family Name: 89LP
• Maximum Speed: 20 MHz
• Operating Supply Voltage: 2.5|3.3 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 38
• Interface Type: 2-Wire/SPI
• On-chip Dac: 8-chx10-bit
• Number Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

14
AT89LP6440 - Preliminary
To enable write access to the nonvolatile data memory, the MWEN bit (MEMCON.4) must be set
to one. When MWEN = 1 and DMEN = 1, MOVX @DPTR,A may be used to write to FDATA.
FDATA uses flash memory with a page-based programming model. Flash data memory differs
from traditional EEPROM data memory in the method of writing data. EEPROM generally can
update a single byte with any value. Flash memory splits programming into write and erase
operations. A Flash write can only program zeroes, i.e change ones into zeroes (
ones in the write data are ignored. A Flash erase sets an entire page of data to ones so that all
bytes become FFH. Therefore after an erase, each byte in the page can be written only once
with any possible value. Bytes can not be overwritten once they are changed from the erased
state without possibility of corrupting the data. Therefore, if even a single byte needs updating;
then the contents of the page must first be saved, the entire page must be erased and the zero
bits in all bytes (old and new data combined) must be written. Avoiding unnecessary page
erases greatly improves the endurance of the memory.
The AT89LP6440 includes 64 data pages of 128 bytes each. One or more bytes in a page may
be written at one time. The AT89LP6440 includes a temporary page buffer of 64 bytes, or half of
a page. Because the page buffer is 64 bytes long, the maximum number of bytes written at one
time is 64. Therefore, two write cycles are required to fill the entire 128-byte page, one for the
low half page (00H–3FH) and one for the high half page (40H–7FH) as shown in
Figure 3-4.
The LDPG bit (MEMCON.5) allows multiple data bytes to be loaded to the temporary page buf-
fer. While LDPG = 1, MOVX @DPTR,A instructions will load data to the page buffer, but will not
start a write sequence. Note that a previously loaded byte must not be reloaded prior to the write
sequence. To write the half page into the memory, LDPG must first be cleared and then a
MOVX @DPTR,A with the final data byte is issued. The address of the final MOVX determines
which half page will be written. If a MOVX @DPTR,A instruction is issued while LDPG = 0 with-
out loading any previous bytes, only a single byte will be written. The page buffer is reset after
each write operation.
writes and page writes.
Figure 3-5.
MWEN
DMEN
MOVX
LDPG
Page Programming Structure
FDATA Byte Write
IDLE
Figures 3-5 and Figure 3-6 on page 15
Data Memory
t
WC
00
Low Half Page
00
Page Buffer
3F
t
40
WC
High Half Page
show the difference between byte
3F
7F
Figure
3706A–MICRO–9/09
1
→
0
3-4.
). Any