GMS97C2051 Datasheet, PDF (8/39 Pages) Hynix Semiconductor – 8-Bit CMOS Microcontorller

GMS97C2051/L2051
Table 6. Formulas for calculating Baud rates
Baud Rate
generated from
Oscillator
Serial Port Mode
0
2
Timer1
1,3
(Timer1 Mode2)
1,3
8-Bit CMOS Microcontroller
Baud Rate
fosc / 12
(2^SMOD x fosc) / 64
(2^SMOD x Timer1 overflow rate) / 32
(2^SMOD x fosc) / [32 x 12 x (256-TH1)]
Interrupt System
The GMS97C2051/L2051 provides 5 interrupt
sources ( two external interrupts, two timer inter-
rupts and serial port interrupt ) with two priority
levels. Figure 4 gives a general overview of the
interrupt sources and illustrates the request and
control flags.
A low-priority interrupt can itself be interrupted by
a high-priority interrupt, but not by another low
priority interrupt. A high-priority interrupt cannot
Figure 4. Interrupt Request Sources


P3.2/
INT0
IT0
TCON.0
IE0
TCON.1 EX0
IE.0
Timer 0 Overflow
P3.3/
INT1
IT1
TCON.2
TF0
TCON.5
ET0
IE.1


IE1
TCON.3 EX1
IE.2
Timer 1 Overflow
TF1
TCON.7
ET1
IE.3
USART
R1
SCON.0

1
T1
ES
SCON.1
IE.4
be interrupted by any other interrupt source.
If two requests of different priority levels are re-
ceived simultaneously, the request of higher
priority is serviced. If requests of the same prior-
ity level are received simultaneously, an internal
polling sequence determines which request is serv-
iced. Thus within each priority level there is a
second priority structure determined by the polling
sequence like Table 8.
High Priority
Low Priority
PX0
IP.0
PT0
IP.1
PX1
IP.2
PT1
IP.3
PS
EA
IP.4
IE.7
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