AT89C51RE2 Atmel Corporation, AT89C51RE2 Datasheet - Page 101

• Manufacturer Part Number: AT89C51RE2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RE2

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Spi: 1
• Uart: 2
• Sram (kbytes): 8.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART/OCD
• Watchdog: Yes

7663E–8051–10/08
Table 68. SCON_0 register
SCON_0 - Serial Control Register for UART 0(98h)
Reset Value = 0000 0000b
Bit addressable
FE/SM0_0
Number
7
Bit
7
6
5
4
3
2
1
0
SM1_0
6
Mnemonic
REN_0
SM0_0
SM1_0
SM2_0
RB8_0
TB8_0
FE_0
RI_0
TI_0
Bit
SM2_0
5
Description
Framing Error bit (SMOD0=1 )
Clear to reset the error state, not cleared by a valid stop bit.
Set by hardware when an invalid stop bit is detected.
SMOD0 must be set to enable access to the FE bit.
Serial port Mode bit 0
Refer to SM1_0 for serial port mode selection.
SMOD0_0 must be cleared to enable access to the SM0_0 bit.
Serial port Mode bit 1
SM0
0
0
1
1
Serial port Mode 2 bit / Multiprocessor Communication Enable bit
Clear to disable multiprocessor communication feature.
Set to enable multiprocessor communication feature in mode 2 and 3, and
eventually mode 1.This bit should be cleared in mode 0.
Reception Enable bit
Clear to disable serial reception.
Set to enable serial reception.
Transmitter Bit 8 / Ninth bit to transmit in modes 2 and 3
Clear to transmit a logic 0 in the 9th bit.
Set to transmit a logic 1 in the 9th bit.
Receiver Bit 8 / Ninth bit received in modes 2 and 3
Cleared by hardware if 9th bit received is a logic 0.
Set by hardware if 9th bit received is a logic 1.
In mode 1, if SM2_0 = 0, RB8 is the received stop bit. In mode 0 RB8 is not used.
Transmit Interrupt flag
Clear to acknowledge interrupt.
Set by hardware at the end of the 8th bit time in mode 0 or at the beginning of the
stop bit in the other modes.
Receive Interrupt flag
Clear to acknowledge interrupt.
Set by hardware at the end of the 8th bit time in mode 0, see Figure 38. and
Figure 39. in the other modes.
SM1
0
1
0
1
REN_0
4
Mode Description
0
1
2
3
Shift Register
8-bit UART
9-bit UART
9-bit UART
TB8_0
3
Baud Rate
F
Variable
F
Variable
CPU PERIPH
CPU PERIPH
RB8_0
2
/6
/32 or /16
AT89C51RE2
TI_0
1
RI_0
0
101