AT89C51RD2 Atmel Corporation, AT89C51RD2 Datasheet - Page 16
AT89C51RD2
Manufacturer Part Number
AT89C51RD2
Description
Manufacturer
Atmel Corporation
Specifications of AT89C51RD2
Flash (kbytes)
64 Kbytes
Max. Operating Frequency
60 MHz
Cpu
8051-12C
Max I/o Pins
32
Spi
1
Uart
1
Sram (kbytes)
2
Self Program Memory
API
Operating Voltage (vcc)
2.7 to 5.5
Timers
4
Isp
UART
Watchdog
Yes
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6.2
Figure 6-1.
6.2.1
16
Xtal2
Xtal1
Functional Block Diagram
AT89C51RD2/ED2
Prescaler Divider
Functional Oscillator Block Diagram
Osc
F
F
In X2 Mode, for CKRL<>0xFF:
In X1 Mode, for CKRL<>0xFF then:
F
F
OSC
CLK CPU
• A hardware RESET puts the prescaler divider in the following state:
• Any value between FFh down to 00h can be written by software into CKRL register in order to
CPU
CPU
divide frequency of the selected oscillator:
• CKRL = FFh: F
•
•
=
=
:2
Reset
F
F
F
F
CKRL = 00h: minimum frequency
CKRL = FFh: maximum frequency
F
F
CLK CPU
CLK CPU
CLK CPU
CLK CPU
and F
CLKPERIPH
CLKPERIPH
CKCON0
CKRL
CLK PERIPH
X2
0
1
= F
= F
= F
= F
CLK PERIPH
CLK PERIPH
CLK PERIPH
CLK PERIPH
=
=
CLK CPU
---------------------------------------------- -
2
---------------------------------------------- -
4
Prescaler-Divider
×
×
(
(
255 CKRL
255 CKRL
F
F
8-bit
= F
= F
OSC
OSC
= F
= F
= F
–
–
Reload
OSC
OSC
OSC
OSC
CLK PERIPH
/1020 (Standard Mode)
/510 (X2 Mode)
/2 (Standard Mode)
(X2 Mode)
)
)
CKRL = 0xFF?
= F
OSC
1
0
/2 (Standard C51 feature)
Idle
CLK
Periph
CLK
CPU
Peripheral Clock
CPU Clock
4235K–8051–05/08