www.STCMCU.com
Mobile:(86)13922809991
Tel:086-755-82948412
Fax:86-755-82905966
Chapter 1. Introduction
STC89C51RC/RD+ series, which is produced by STC MCU Limited, is a 8-bit single-chip microcontroller
with a fully compatible instruction set with industrial-standard 8051 series microcontroller. There is 64K bytes
flash memory embeded for appliaction program, which is shared with In-System-Programming code.In-System-
Programming (ISP) and In-Application-Programming (IAP) support the users to upgrade the program and data
in system. ISP allows the user to download new code without removing the microcontroller from the actual end
product;IAP means that the device can write non-valatile data in Flash memory while the application program
is running. There are 1280 bytes or 512 bytes on-chip RAM embedded that provides requirement from wide
field application. The user can configure the device to run in 12 clocks per machine cycle, and to get the same
performance just as he uses another standard 80C51 device that is provided by other vendor, or 6 clocks per
machine cycle to achieve twice performance. The STC89C51RC/RD+ series retain all features of the standard
80C51. In addition, the STC89xx series have a extra I/O port (P4 ), Timer 2, a 8-sources, 4-priority-level interrupt
structure, on-chip crystal oscillator,and a one-time enabled Watchdog Timer.
ited.1.1 Features
• Enhanced 80C51 Central Processing Unit ,6T or 12T per machine cycle
Lim• Operation voltage range: 5.5V~3.3V (STC89C51RC/RD+ series) or 2.0V~ 3.6V (STC89LE51RC/RD+ series)
• Operation frequency range: 0-40MHz @ 6T, or 0- 80MHz @12T, the actual operation frequency can up to
48MHz
CU• On-chip 4K/8K/13K/16K/32K/40K/48K/56K/61K FLASH program memory with flexible ISP/IAP capability
M• On-chip 1280 byte / 512 byte RAM
• Be capable of addressing up to 64K byte of external RAM
STC• Be capable of addressing up to 64K bytes external memory
• Dual Data Pointer (DPTR) to speed up data movement
• Three 16-bit timer/counter, Timer 2 is an up/down counter with programmable clcok output on P1.0
• 8 vector-address, 4 level priority interrupt capability
• One enhanced UART with hardware address-recognition, frame-error detection function, and with self baud-
rate generator.
• One 15 bits Watch-Dog-Timer with 8-bit pre-scaler (one-time-enabled)
• integrate MAX810 — specialized reset circuit
• Two power management modes: idle mode and power-down mode
• Low EMI: inhibit ALE emission
• Power down mode can be woken-up by INT0/P3.2 pin, INT1/P3.3 pin, T0/P3.4, T1/P3.5, RXD/P3.0 pin,
INT2/P4.3, INT3/P4.2
• 39 or 35 programmable I/O ports are available
• Four 8-bit bi-directonal ports; extra four-bit additional P4 are available for PLCC-44 and LQFP-44
• Operating temperature: -40 ~ +85oC (industrial) / 0~75oC (commercial)
• package type : LQFP-44, PDIP-40, PLCC-44
STC MCU Limited.
website：www.STCMCU.com
www.STCMCU.com
Mobile:(86)13922809991
Tel:086-755-82948412
Fax:86-755-82905966
1.6 STC89C51RC/RD+ series Application Circuit for ISP
Vcc STC3232,STC232,MAX232,SP232
PC COM
1 C1+
0.1μF 2 V+
Vcc 16 +
Gnd 15
Vcc
Gnd
2
3
3 C1-
T1OUT 14 PC_RxD(COM Pin2)
5
4 C2+
R1IN 13 PC_TxD(COM Pin3)
5 C2-
R1OUT 12
6 V-
7 T2OUT
8 R2IN
T1IN 11
T2IN 10
R2OUT 9
This part of the circuit
has nothing to do
with the downloads
U1-P1.0
Vcc
U1-P1.1
MCU-VCC
U1-P3.0
1K
1 T2/P1.0
U1-P3.1
Gnd
2 T2EX/P1.1
MCU10μF + C1
STC10K R1
MCU_RxD(P3.0)
3 P1.2
4 P1.3
5 P1.4
6 P1.5
7 P1.6
8 P1.7
9 RST
10 RxD/P3.0
MCU_TxD(P3.1)
11 TxD/P3.1
※ How to identify 90C and HD version:
See the the last few letters of the bottom
line of MCU surface text
12 INT0/P3.2
13 INT1/P3.3
14 T0/P3.4
15 T1/P3.5
C2<47pF
16 WR/P3.6
17 RD/P3.7
USB+5V T1OUT R1IN GND
X1
18 XTAL2
19 XTAL1
USB1
C1<47pF
20 Gnd
System Power/USB +5V
Limited.Vcc 40
P0.0 39
P0.1 38
1K
P0.2 37
P0.3 36
P0.4 35
P0.5 34
P0.6 33
P0.7 32
EA/P4.6 31
ALE/P4.5 30
PSEN/P4.4 29
P2.7/A15 28
1K
P2.6/A14 27
P2.5/A13 26
P2.4/A12 25
P2.3/A11 24
P2.2/A10 23
P2.1/A9 22
P2.0/A8 21
SW1
Power On
C6 + C5
104 10μF
About reset circuit:
When the crystal frequency X1 is 4MHz, capacitors C2 and C3 should all be 100pF.
When the crystal frequency X1 is 6MHz, capacitors C2 and C3 should all be 47pF ~ 100pF.
When the crystal frequency X1 is 12~25MHz, capacitors C2 and C3 should all be 47pF.
1. When R/C reset, capacitor C1 is 10uF and resistor R1 isto 10K
2.RC/RD+ series HD version MCU, RESET pin is connected to internal pull-down resistor 45K-100K
12 STC MCU Limited.
website：www.STCMCU.com
