P89CV51RD2FBC,557 NXP Semiconductors, P89CV51RD2FBC,557 Datasheet - Page 35

• Manufacturer Part Number: P89CV51RD2FBC,557
• Description: IC 80C51 MCU FLASH 64K 44-TQFP
• Manufacturer: NXP Semiconductors
• Series: 89Cr

Specifications of P89CV51RD2FBC,557

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: EBI/EMI, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Processor Series: P89CV5x
• Core: 80C51
• Data Bus Width: 8 bit
• Data Ram Size: 1 KB
• Interface Type: SPI, UART
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 4.5 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Minimum Operating Temperature: - 40 C
• Cpu Family: 89C
• Device Core: 80C51
• Device Core Size: 8b
• Frequency (max): 40MHz
• Total Internal Ram Size: 1KB
• # I/os (max): 32
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 4.5V
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 44
• Package Type: TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Details
• Other names: 568-4257; 935284103557; P89CV51RD2FBC

NXP Semiconductors
P89CV51RB2_RC2_RD2_3
Product data sheet
6.5.5 Summary of baud rate equations
The Baud rate generator mode is like the Auto-reload mode, when a roll-over in TH2
causes the Timer 2 registers to be reloaded with the 16-bit value in registers RCAP2H and
RCAP2L, which are preset by software.
The baud rates in modes 1 and 3 are determined by Timer 2’s overflow rate given below:
The timer can be configured for either ‘timer’ or ‘counter’ operation. In many applications,
it is configured for ‘timer' operation (C/T2 = 0). Timer operation is different for Timer 2
when it is being used as a baud rate generator.
Usually, as a timer it would increment at every machine cycle (i.e.,
frequency). As a baud rate generator, it increments at the oscillator frequency. Thus the
baud rate formula is shown in
Where: (RCAP2H, RCAP2L) = the content of RCAP2H and RCAP2L taken as a 16-bit
unsigned integer.
The Timer 2 in Baud rate generator mode is valid only if RCLK and/or TCLK = 1 in T2CON
register. Note that a roll-over in TH2 does not set TF2, and will not generate an interrupt.
Thus, the Timer 2 interrupt does not have to be disabled when Timer 2 is in the Baud rate
generator mode. Also if the EXEN2 (T2 external enable flag) is set, a 1-to-0 transition in
T2EX (timer/counter 2 trigger input) will set EXF2 (T2 external flag) but will not cause a
reload from (RCAP2H, RCAP2L) to (TH2, TL2). Therefore when Timer 2 is used as a
baud rate generator, T2EX can be used as an additional external interrupt, if needed.
When Timer 2 is in the Baud rate generator mode, one should not try to read or write TH2
and TL2. Under these conditions, a read or write of TH2 or TL2 may not be accurate. The
RCAP2 registers may be read, but should not be written to, because a write might overlap
a reload and cause write and/or reload errors. The timer should be turned off (clear TR2)
before accessing the Timer 2 or RCAP2 registers.
rates and how they can be obtained from Timer 2.
Timer 2 is in Baud rate generator mode: if Timer 2 is being clocked through pin T2 (P1[0])
the baud rate is:
If Timer 2 is being clocked internally, the baud rate is:
Where f
To obtain the reload value for RCAP2H and RCAP2L, this equation can be rewritten as:
---------------------------------------------------------------------------------------------
16
Modes 1 and 3 baud rates = Timer 2 overflow rate / 16
Modes 1 and 3 baud rates =
Baud rate = Timer 2 overflow rate / 16
Baud rate = f
RCAP2H, RCAP2L = 65536
65536
OscillatorFrequency
osc
= oscillator frequency
–
RCAP2H RCAP2L
osc
/ (16
Rev. 03 — 25 August 2009
(65536
Equation
f
osc
(RCAP2H, RCAP2L)))
/ (16
3:
P89CV51RB2/RC2/RD2
baud rate)
Table 23
shows commonly used baud
80C51 with 1 kB RAM, SPI
1
6
the oscillator
© NXP B.V. 2009. All rights reserved.
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