AT89C5132 Atmel Corporation, AT89C5132 Datasheet - Page 111

• Manufacturer Part Number: AT89C5132
• Manufacturer: Atmel Corporation

Specifications of AT89C5132

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-12C
• Max I/o Pins: 44
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Uart: 1
• Adc Channels: 2
• Adc Resolution (bits): 10
• Adc Speed (ksps): 22.7
• Sram (kbytes): 2.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 3.6
• Timers: 2
• Isp: UART/USB
• Watchdog: Yes

18.4
18.4.0.1
18.4.0.2
18.4.1
4173E–USB–09/07
Asynchronous Modes (Modes 1, 2 and 3)
Transmission
(Modes 1, 2 and 3)
Mode 1
Modes 2 and 3
The Serial Port has one 8-bit and two 9-bit asynchronous modes of operation. Figure 18-8
shows the Serial Port block diagram in asynchronous modes.
Figure 18-8. Serial I/O Port Block Diagram (Modes 1, 2 and 3)
Mode 1 is a full-duplex, asynchronous mode. The data frame (see Figure 18-9) consists of 10
Bits: one start, eight data Bits and one stop bit. Serial data is transmitted on the TXD pin and
received on the RXD pin. When data is received, the stop bit is read in the RB8 bit in SCON
register.
Figure 18-9. Data Frame Format (Mode 1)
Modes 2 and 3 are full-duplex, asynchronous modes. The data frame (see Figure 18-10) con-
sists of 11 Bits: one start bit, eight data Bits (transmitted and received LSB first), one
programmable ninth data bit and one stop bit. Serial data is transmitted on the TXD pin and
received on the RXD pin. On receive, the ninth bit is read from RB8 bit in SCON register. On
transmit, the ninth data bit is written to TB8 bit in SCON register. Alternatively, the ninth bit can
be used as a command/data flag.
Figure 18-10. Data Frame Format (Modes 2 and 3)
To initiate a transmission, write to SCON register, setting SM0 and SM1 Bits according to
Table 89, and setting the ninth bit by writing to TB8 bit. Then, writing the byte to be transmitted to
SBUF register starts the transmission.
Mode 1
CLOCK
CLOCK
CLOCK
IBRG
PER
T1
Start bit
Start bit
SCON.4
SM2
D0
SCON.6
M3 M2 M1 M0
SM1
Mode Decoder
Mode & Clock
D0
Controller
D1
SCON.1
TI
D1
SCON.7
D2
SM0
SCON.0
D2
RI
D3
9-bit data
D3
8-bit data
D4
D4
D5
D5
SBUF Tx SR
SBUF Rx
D6
Rx SR
SCON.3
TB8
D6
D7
AT89C5132
D7
D8
SCON.2
Stop bit
RB8
Stop bit
TXD
RXD
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