AT89C51RE2-SLSUM Atmel, AT89C51RE2-SLSUM Datasheet - Page 71

• Manufacturer Part Number: AT89C51RE2-SLSUM
• Description: MCU 8BIT FLASH 2.7-5.5V 44-PLCC
• Manufacturer: Atmel
• Series: 89Cr

Specifications of AT89C51RE2-SLSUM

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 60MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 34
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-PLCC
• Package: 44PLCC
• Device Core: 8051
• Family Name: 89C
• Maximum Speed: 40 MHz
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 34
• Interface Type: SPI/TWI/UART
• Number Of Timers: 3
• Processor Series: AT89x
• Core: 8051
• Data Ram Size: 8 KB
• Maximum Clock Frequency: 40 MHz
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: AT89OCD-01
• Minimum Operating Temperature: - 40 C
• Cpu Family: 89C
• Device Core Size: 8b
• Frequency (max): 40MHz
• Total Internal Ram Size: 8KB
• # I/os (max): 34
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 44
• Package Type: PLCC
• For Use With: AT89OCD-01 - USB EMULATOR FOR AT8XC51 MCUAT89STK-11 - KIT STARTER FOR AT89C51RX2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Timer 1
Mode 0 (13-bit Timer)
Mode 1 (16-bit Timer)
Mode 2 (8-bit Timer
with Auto-Reload)
Mode 3 (Halt)
Interrupt
7663E–8051–10/08
Timer 1 is identical to Timer 0 excepted for Mode 3 which is a hold-count mode. The following
comments help to understand the differences:
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Mode 0 configures Timer 1 as a 13-bit Timer, which is set up as an 8-bit Timer (TH1 register)
with a modulo-32 prescaler implemented with the lower 5 bits of the TL1 register (see
Figure 23). The upper 3 bits of TL1 register are ignored. Prescaler overflow increments TH1
register.
Mode 1 configures Timer 1 as a 16-bit Timer with TH1 and TL1 registers connected in cascade
(see Figure 24). The selected input increments TL1 register.
Mode 2 configures Timer 1 as an 8-bit Timer (TL1 register) with automatic reload from TH1 reg-
ister on overflow (see Figure 25). TL1 overflow sets TF1 flag in TCON register and reloads TL1
with the contents of TH1, which is preset by software. The reload leaves TH1 unchanged.
Placing Timer 1 in mode 3 causes it to halt and hold its count. This can be used to halt Timer 1
when TR1 run control bit is not available i.e. when Timer 0 is in mode 3.
Each Timer handles one interrupt source that is the timer overflow flag TF0 or TF1. This flag is
set every time an overflow occurs. Flags are cleared when vectoring to the Timer interrupt rou-
tine. Interrupts are enabled by setting
globally enabled by setting EA bit in IEN0 register.
Timer 1 functions as either a Timer or event Counter in three modes of operation. Figure 23
to Figure 25 show the logical configuration for modes 0, 1, and 2. Timer 1’s mode 3 is a
hold-count mode.
Timer 1 is controlled by the four high-order bits of TMOD register (see Figure 47) and bits 2,
3, 6 and 7 of TCON register (see Figure 46). TMOD register selects the method of Timer
gating (GATE1), Timer or Counter operation (C/T1#) and mode of operation (M11 and M01).
TCON register provides Timer 1 control functions: overflow flag (TF1), run control bit (TR1),
interrupt flag (IE1) and interrupt type control bit (IT1).
Timer 1 can serve as the Baud Rate Generator for the Serial Port. Mode 2 is best suited for
this purpose.
For normal Timer operation (GATE1 = 0), setting TR1 allows TL1 to be incremented by the
selected input. Setting GATE1 and TR1 allows external pin INT1# to control Timer operation.
Timer 1 overflow (count rolls over from all 1s to all 0s) sets the TF1 flag generating an
interrupt request.
When Timer 0 is in mode 3, it uses Timer 1’s overflow flag (TF1) and run control bit (TR1).
For this situation, use Timer 1 only for applications that do not require an interrupt (such as a
Baud Rate Generator for the Serial Port) and switch Timer 1 in and out of mode 3 to turn it
off and on.
It is important to stop Timer/Counter before changing mode.
ETx
bit in IEN0 register. This assumes interrupts are
AT89C51RE2
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