VRS51C1100-40-L ETC1 [List of Unclassifed Manufacturers], VRS51C1100-40-L Datasheet - Page 22

• Manufacturer Part Number: VRS51C1100-40-L
• Description: Versa 8051 MCU with 128KB of IAP/ISP Flash
• Manufacturer: ETC1 [List of Unclassifed Manufacturers]

the RCAP2L and RCAP2H registers. Furthermore, the
transition at T2EX causes bit EXF2 in T2CON to be
set, and EXF2, like TF2, can generate an interrupt.
Note that both EXF2 and TF2 share the same interrupt
vector.
Timer 2 Auto-Reload Mode
In this mode, there are also two options controlled by
the EXEN2 bit in the T2CON register.
If EXEN2 = 0, when Timer 2 rolls over, it not only sets
TF2, but also causes the Timer 2 registers to be
reloaded with the 16-bit value in the RCAP2L and
RCAP2H registers previously initialised. In this mode,
Timer 2 can be used as a baud rate generator source
for the serial port.
If EXEN2=1, then Timer 2 still performs the above
operation, but a 1 to 0 transition at the external T2EX
input will also trigger an anticipated reload of Timer 2
with the value stored in RCAP2L, RCAP2H and set
EXF2.
F
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IGURE
VRS51C1100
T2EX pin
T2 pin
F
OSC
15: T
IMER
EXEN2
÷12
2
C/T2
IN AUTO
0
1
-
RELOAD MODE
TR2
COUNTER
TIMER
0
0
RCAP2L
TL2
7
7
0
0
EXF2
RCAP2H
TH2
7
Interrupt
7
Timer 2
TF2
Timer 2 Baud Rate Generator Mode
Timer 2 can be used for UART Baud Rate generation.
This mode is activated when RCLK is set to 1 and/or
TCLK is set to 1. This mode is described further in the
serial port section.
UART Serial Port
The serial port on the VRS51C1100 can operate in full
duplex
simultaneously.) This occurs at the same speed if one
timer is assigned as the clock source for both
transmission and reception, and at different speeds if
transmission and reception are each controlled by their
own timer.
The VRS51C1100 serial port includes a double buffer
for the receiver, which allows reception of a byte even
if the previously received byte has not been retrieved
from the receive register by the processor. However, if
the first byte still has not been read by the time
reception of the second byte is complete, the byte
present in the receive buffer will be lost.
The SBUF register provides access to the transmit and
receive registers of the serial port. Reading from the
SBUF register will access the receive register, while a
write to the SBUF loads the transmit register.
F
T2EX pin
T2 pin
IGURE
F
OSC
16: T
IMER
EXEN2
÷2
C/T2
(it
2
IN AUTOMATIC
0
1
can
TR2
COUNTER
TIMER
Timer 1 Overflow
B
transmit
AUD
G
ENERATOR
÷2
0
0
0
1
SMOD
M
RCAP2L
and
TL2
ODE
1
0
TCLK
7
7
0
0
receive
page 22 of 50
EXF2
1
0
RCLK
RCAP2H
TH2
7
7
÷16
÷16
data
TX Clock
RX Clock
Timer 2
Interrupt
Request