AT89LP6440-20AU Atmel, AT89LP6440-20AU Datasheet - Page 65

• 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

Figure 12-6. Timer 2 Waveform: Auto-Reload Mode (DCEN = 1)
12.3.3
3706A–MICRO–9/09
Dual Slope Counter
BOTTOM
T2EX
EXF2
When Timer 2 Auto-Reload Mode uses Count Mode 2 (T2CM
(T2CM
TOP and then counts down from TOP to MIN, following a sawtooth waveform as shown in
ure
0and Down = 1). The value of TOP stored in RCAP2H and RCAP2L is double-buffered such that
a new TOP value takes affect only after an underflow. The only difference between Mode 2 and
Mode 3 is when the interrupt flag is set. In Mode 2 TF2 is set once per count period when the
timer underflows at MIN. In Mode 3 TF2 is set twice per count period, once when the timer over-
flows at TOP and once when the timer underflows at MIN. The interrupt service routine can
check the EXF2 bit to determine if TF2 was set at TOP or MIN. These count modes are provided
to support variable precision symmetrical PWM in the CCA. DCEN has no effect when using
dual slope operation. The Timer 2 overflow rate for this mode is given in the following equation:
MAX
MAX
TOP
MIN
MIN
DCEN = 0, T2CM = 10B
12-7. The EXF2 bit is set/cleared by hardware to reflect the current count direction (Up =
Auto-Reload Mode:
1-0
= 11B), the timer operates in a dual slope fashion. The timer counts up from MIN to
Time-out Period
T2CM
T2CM
1-0
1-0
= 00B, DCEN = 1
= 01B, DCEN = 1
AT89LP6440 - Preliminary
=
{
------------------------------------------------------------------ -
RCAP2H RCAP2L
Oscillator Frequency
,
1-0
TF2 Set
TF2 Set
= 10B) or Count Mode 3
}
×
2
×
(
TPS
+
1
)
Fig-
65