AT80C51RD2-SLSIM Atmel, AT80C51RD2-SLSIM Datasheet - Page 8

• Manufacturer Part Number: AT80C51RD2-SLSIM
• Description: IC MCU 8051 5V SPI 20MHZ 44-PLCC
• Manufacturer: Atmel
• Series: 80Cr

Specifications of AT80C51RD2-SLSIM

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Type: ROMless
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

5. Oscillators
5.1
5.2
5.2.1
8
Overview
Registers
AT80C51RD2
Prescaler Divider
One oscillator is available for CPU:
In order to optimize the power consumption and the execution time needed for a specific task,
an internal prescaler feature has been implemented between the selected oscillator and the
CPU.
Table 5-1.
Reset Value = 1111 1111b
Not bit addressable
A hardware RESET puts the prescaler divider in the following state:
• OSC used for high frequency (3 MHz to 40 MHz)
• CKRL = FFh: F
• Any value between FFh down to 00h can be written by software into CKRL register in order to
Number
KS signal selects OSC: F
divide frequency of the selected oscillator:
7:0
Bit
7
-
– CKRL = 00h: minimum frequency
– CKRL = FFh: maximum frequency
– F
F
F
F
F
In X2 mode:
In X1 mode:
CLK CPU
CLK CPU
CLK CPU
CLK CPU
CLK CPU
Mnemonic
CKRL
Clock Reload Register
Bit
= F
= F
= F
= F
and F
6
-
CLK CPU
CLK PERIPH
CLK PERIPH
CLK PERIPH
CLK PERIPH
CLK PERIPH
Description
Clock Reload Register: Prescaler value
F
F
= F
CPU
CPU
CLK OUT
CLK PERIPH
5
-
= F
= F
= F
= F
=
=
F
F
OSC
OSC
OSC
OSC
CLKPERIPH
CLKPERIPH
= F
/1020 (Standard Mode)
/510 (X2 Mode)
/2 (Standard Mode)
(X2 Mode)
= F
OSC
4
-
OSC
=
=
/2 (Standard C51 feature)
--------------------------------------------- -
2
--------------------------------------------- -
4
×
×
(
(
255 CKRL
255 CKRL
F
F
OSCA
3
OSC
-
–
–
)
)
2
-
1
-
4113D–8051–01/09
0
-