p89cv51rb2 NXP Semiconductors, p89cv51rb2 Datasheet - Page 34

• Manufacturer Part Number: p89cv51rb2
• Description: P89cv51rb2/rc2/rd2 8-bit 80c51 5 V Low Power 64 Kb Flash Microcontroller With 1 Kb Ram, Spi, 6-clock Cpu With 6/12-clock Peripherals
• Manufacturer: NXP Semiconductors

NXP Semiconductors
P89CV51RB2_RC2_RD2_1
Product data sheet
6.6.1 Mode 0
6.6.2 Mode 1
6.6.3 Mode 2
6.6.4 Mode 3
6.6 UART
Table 23.
The UART operates in all standard modes. Enhancements over the standard 80C51
UART include framing error detection, and automatic address recognition.
Serial data enters and exits through RXD, and TXD outputs the shift clock. Only 8 bits are
transmitted or received, LSB first. The baud rate is fixed at
The UART configured to operate in this mode outputs serial clock on the TXD line no
matter whether it sends or receives data on the RXD line.
10 bits are transmitted (through TXD) or received (through RXD): a start bit (logical 0), 8
data bits (LSB first), and a stop bit (logical 1). When data is received, the stop bit is stored
in RB8 in special function register SCON. The baud rate is variable and is determined by
the Timer 1/Timer 2 overflow rate.
11 bits are transmitted (through TXD) or received (through RXD): start bit (logical 0), 8
data bits (LSB first), a programmable 9th data bit, and a stop bit (logical 1). When data is
transmitted, the 9th data bit (TB8 in special function register SCON) can be assigned the
value of 0 or (e.g. the parity bit (P in special function register PSW) could be moved into
bit TB8). When data is received, 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
the CPU clock frequency, as determined by the SMOD1 bit in PCON.
11 bits are transmitted (through TXD) or received (through RXD): a start bit (logical 0), 8
data bits (LSB first), a programmable 9th data bit, and a stop bit (logical 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 and is determined by the Timer 1/Timer 2 overflow rate.
Rate
750 kBd
19.2 kBd
9.6 kBd
4.8 kBd
2.4 kBd
600 Bd
220 Bd
600 Bd
220 Bd
Timer 2-generated commonly used baud rates
Rev. 01 — 5 October 2007
Oscillator frequency
12 MHz
12 MHz
12 MHz
12 MHz
12 MHz
12 MHz
12 MHz
6 MHz
6 MHz
P89CV51RB2/RC2/RD2
Timer 2
RCAP2H
FF
FF
FF
FF
FE
FB
F2
FD
F9
1
6
of the CPU clock frequency.
80C51 with 1 kB RAM, SPI
RCAP2L
FF
D9
B2
64
C8
1E
AF
8F
57
© NXP B.V. 2007. All rights reserved.
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