UPSD3234A-40U6T STMicroelectronics, UPSD3234A-40U6T Datasheet - Page 66

• Manufacturer Part Number: UPSD3234A-40U6T
• Description: IC MCU 8032 64KB FLASH 80TQFP
• Manufacturer: STMicroelectronics
• Series: µPSDr

Specifications of UPSD3234A-40U6T

• Core Processor: 8032
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, UART/USART, USB
• Peripherals: LVR, POR, PWM, WDT
• Number Of I /o: 46
• Program Memory Size: 288KB (288K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 4x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-TQFP, 80-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

Standard serial interface (UART)
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Standard serial interface (UART)
The UPSD323xx devices provides two standard 8032 UART serial ports. The first port is
connected to pin P3.0 (RX) and P3.1 (TX). The second port is connected to pin P1.2 (RX)
and P1.3(TX). The operation of the two serial ports are the same and are controlled by the
SCON and SCON2 registers.
The serial port is full duplex, meaning it can transmit and receive simultaneously. It is also
receive-buffered, meaning it can commence reception of a second byte before a previously
received byte has been read from the register. (However, if the first byte still has not been
read by the time reception of the second byte is complete, one of the bytes will be lost.) The
serial port receive and transmit registers are both accessed at Special Function Register
SBUF (or SBUF2 for the second serial port). Writing to SBUF loads the transmit register,
and reading SBUF accesses a physically separate receive register.
The serial port can operate in 4 modes: Mode 0, 1, 2 or 3.
Mode 0
Serial data enters and exits through RxD. TxD outputs the shift clock. 8 bits are
transmitted/received (LSB first). The baud rate is fixed at 1/12 the f
Mode 1
10 bits are transmitted (through TxD) or received (through RxD): a Start bit (0), 8 data bits
(LSB first), and a Stop bit (1). On receive, the Stop bit goes into RB8 in Special Function
Register SCON. The baud rate is variable.
Mode 2
11 bits are transmitted (through TxD) or received (through RxD): Start bit (0), 8 data bits
(LSB first), a programmable 9th data bit, and a Stop bit (1). On Transmit, the 9th data bit
(TB8 in SCON) can be assigned the value of ‘0’ or ‘1’. Or, for example, the Parity bit (P, in the
PSW) could be moved into TB8. On receive, the 9th data bit goes into RB8 in Special
Function Register SCON, while the Stop bit is ignored. The baud rate is programmable to
either 1/32 or 1/64 the oscillator frequency.
Mode 3
11 bits are transmitted (through TxD) or received (through RxD): a Start bit (0), 8 data bits
(LSB first), a programmable 9th data bit, and a Stop bit (1). In fact, Mode 3 is the same as
Mode 2 in all respects except baud rate. The baud rate in Mode 3 is variable.
In all four modes, transmission is initiated by any instruction that uses SBUF as a destination
register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. Reception is
initiated in the other modes by the incoming start bit if REN = 1.
Multiprocessor communications
Modes 2 and 3 have a special provision for multiprocessor communications. In these
modes, 9 data bits are received. The 9th one goes into RB8. Then comes a Stop bit. The
port can be programmed such that when the Stop bit is received, the serial port interrupt will
UPSD3234A, UPSD3234BV, UPSD3233B, UPSD3233BV
OSC
.