AT89LP6440-20PU Atmel, AT89LP6440-20PU Datasheet - Page 76

• Manufacturer Part Number: AT89LP6440-20PU
• Description: MCU 8051 64K FLASH ISP 40PDIP
• Manufacturer: Atmel
• Series: 89LPr

Specifications of AT89LP6440-20PU

• 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: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

13.3.2
13.4
76
Pulse Width Modulation Mode
AT89LP6440 - Preliminary
Timer 2 Operation for Compare Mode
Figure 13-6. Dual-Slope Waveform Example
Compare channels will work with any Timer 2 operating mode. The full 16-bit compare range
may not be available in all modes. In order for a compare output action to take place, the com-
pare values must be within the counting range of Timer 2. CTCx must be cleared to 0 for all
channels if Timer 2 is operating in Baud Rate mode or errors may occur in the serial
communication.
In Pulse Width Modulation (PWM) Mode, a compare channel can output a square wave with pro-
grammable frequency and duty cycle. Setting CCMx = 1 and CxM
Mode. PWM Mode is similar to Output Compare Mode except that the compare value is double-
buffered. A diagram of a CCA channel in PWM Mode is shown in
is selectable between inverting and non-inverting modes. PWM is intended for use with Timer 2
in Auto-Reload Mode (CP/RL2 = 0, DCEN = 0) using count modes 1, 2 or 3. The PWM can oper-
ate in asymmetric (edge-aligned) or symmetric (center-aligned) mode depending on the T2CM
selection. The CCA PWM has variable precision from 2 to 16 bits. A trade-off between frequency
and precision is made by changing the TOP value of the timer. The CCA PWM always uses the
greatest precision allowable for the selected output frequency, as compared to Timer 0 and 1
whose PWMs are fixed at 8-bit precision regardless of frequency.
Figure 13-7. CCA PWM Mode Diagram
{RCAP2H,RCA2L}
{CCAH,CCAL}
{CCBH,CCBL}
T2CCL
CCxL
shadow
TL2
CCA
CCB
shadow
T2CCH
CCxH
shadow
TH2
=
T2CCC
CCCx
CP/RL2 = 0, T2CM
CCFx
1-0
CIENx
CxM
= 10B, DCEN = 0
2-0
Figure
2-0
13-7. The PWM polarity
= 10xB enables PWM
Interrupt
CCx (P2.x)
3706A–MICRO–9/09