AT89LP6440-20AU Atmel, AT89LP6440-20AU Datasheet - Page 62

• 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 12-1. Timer 2 Diagram: Capture Mode
12.3
12.3.1
62
Auto-Reload Mode
AT89LP6440 - Preliminary
Up Counter
T2EX PIN
OSC
T2 PIN
Timer 2 can be programmed to count up or down when configured in its 16-bit auto-reload
mode. This feature is invoked by the DCEN (Down Counter Enable) bit located in the SFR
T2MOD (see
count up. When DCEN is set, Timer 2 can count up or down, depending on the value of the
T2EX pin. The overflow and reload values depend on the Timer 2 Count Mode bits, T2CM
T2MOD. A summary of the Auto-Reload behaviors is listed in
Table 12-5.
Figure 12-2
this mode Timer 2 counts up to MAX and then sets the TF2 bit upon overflow. The overflow also
causes the timer registers to be reloaded with BOTTOM, the 16-bit value in RCAP2H and
RCAP2L. If EXEN2 = 1, a 16-bit reload can be triggered either by an overflow or by a 1-to-0 tran-
sition at external input T2EX. This transition also sets the EXF2 bit. Both the TF2 and EXF2 bits
can generate an interrupt. The Timer 2 overflow rate for this mode is given in the following
equation:
Timer 2 may also be configured to count from MIN to TOP instead of BOTTOM to MAX by set-
ting T2CM
DCEN = 0, T2CM = 00B
÷TPS
T2CM
Auto-Reload Mode:
TRANSITION
DETECTOR
00
00
00
01
01
01
10
11
1-0
1-0
shows Timer 2 automatically counting up when DCEN = 0 and T2CM
= 01B. In this mode Timer 2 counts up to TOP, the 16-bit value in RCAP2H and
Table
Summary of Auto-Reload Modes
C/T2 = 0
C/T2 = 1
DCEN
12-4). Upon reset, the DCEN bit is set to 0 so that timer 2 will default to
X
X
0
1
1
0
1
1
EXEN2
TR2
T2EX
CAPTURE
X
0
1
X
0
1
X
X
Time-out Period
Direction
Up-Down
Up-Down
Down
Down
Up
Up
Up
Up
RCAP2L
TL2
EXF2
=
RCAP2H
Behavior
BOTTOM
MAX
BOTTOM
MIN
TOP
MIN
MIN
MIN
65536
------------------------------------------------------------------------------ -
TH2
→
→
→
→
→
→
Oscillator Frequency
TOP
TOP
MIN
TOP
TOP
BOTTOM
–
OVERFLOW
→
→
{
RCAP2H RCAP2L
Table
MAX
MAX
→
→
reload to MIN
underflow to TOP
overflow to MIN
TF2
MIN
MIN
reload to BOTTOM
underflow to MAX
overflow to BOTTOM
12-5.
and repeat
and repeat
,
INTERRUPT
TIMER 2
}
3706A–MICRO–9/09
×
1-0
(
TPS
= 00B. In
+
1-0
1
)
in