AT89LP6440-20AU Atmel, AT89LP6440-20AU Datasheet - Page 50

• 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

11. Enhanced Timer 0 and Timer 1 with PWM
50
AT89LP6440 - Preliminary
The AT89LP6440 has two 16-bit Timer/Counters, Timer 0 and Timer 1, with the following
features:
Timer 0 and Timer 1 have similar modes of operation. As timers, the timer registers increase
every clock cycle by default. Thus, the registers count clock cycles. Since a clock cycle consists
of one oscillator period, the count rate is equal to the oscillator frequency. The timer rate can be
prescaled by a value between 1 and 16 using the Timer Prescaler (see
Both Timers share the same prescaler.
As counters, the timer registers are incremented in response to a 1-to-0 transition at the corre-
sponding input pins, T0 or T1. The external input is sampled every clock cycle. When the
samples show a high in one cycle and a low in the next cycle, the count is incremented. The new
count value appears in the register during the cycle following the one in which the transition was
detected. Since 2 clock cycles are required to recognize a 1-to-0 transition, the maximum count
rate is 1/2 of the oscillator frequency. There are no restrictions on the duty cycle of the input sig-
nal, but it should be held for at least one full clock cycle to ensure that a given level is sampled at
least once before it changes.
Furthermore, the Timer or Counter functions for Timer 0 and Timer 1 have four operating modes:
variable width timer, 16-bit auto-reload timer, 8-bit auto-reload timer, and split timer. The control
bits C/T in the Special Function Register TMOD select the Timer or Counter function. The bit
pairs (M1, M0) in TMOD select the operating modes.
Table 11-1.
Name
TCON
TMOD
TL0
TL1
TH0
TH1
TCONB
RL0
RL1
RH0
RH1
• Two 16-bit timer/counters with 16-bit reload registers
• Two independent 8-bit precision PWM outputs with 8-bit prescalers
• UART or SPI baud rate generation using Timer 1
• Output pin toggle on timer overflow
• Split timer mode allows for three separate timers (2 8-bit, 1 16-bit)
• Gated modes allow timers to run/halt based on an external input
Address
Timer 0/1 Register Summary
8AH
8BH
8CH
8DH
88H
89H
91H
92H
93H
94H
95H
Purpose
Control
Mode
Timer 0 low-byte
Timer 1 low-byte
Timer 0 high-byte
Timer 1 high-byte
Mode
Timer 0 reload low-byte
Timer 1 reload low-byte
Timer 0 reload high-byte
Timer 1 reload high-byte
Table 6-2 on page
Bit-Addressable
3706A–MICRO–9/09
N
N
N
N
N
N
N
N
N
N
Y
32).