XA-G39 Datasheet, PDF (22/42 Pages) NXP Semiconductors – XA 16-bit microcontroller family XA 16-bit microcontroller 32K FLASH/1K RAM, watchdog, 2 UARTs

Philips Semiconductors
XA 16-bit microcontroller family
32K Flash/1K RAM, watchdog, 2 UARTs
Preliminary data
XA-G39
timer register is loaded with FFFF hex. The underflow also sets the
TF2 flag, which can generate an interrupt if enabled.
The external flag EXF2 toggles when Timer 2 underflows or
overflows. This EXF2 bit can be used as a 17th bit of resolution, if
needed. the EXF2 flag does not generate an interrupt in this mode.
As the baud rate generator, timer T2 is incremented by TCLK.
Baud Rate Generator Mode
By setting the TCLKn and/or RCLKn in T2CON or T2MOD, the
Timer 2 can be chosen as the baud rate generator for either or both
UARTs. The baud rates for transmit and receive can be
simultaneously different.
Programmable Clock-Out
A 50% duty cycle clock can be programmed to come out on P1.6.
This pin, besides being a regular I/O pin, has two alternate
functions. It can be programmed (1) to input the external clock for
Table 4. Timer 2 Operating Modes
TR2
CP/RL2
RCLK+TCLK
0
X
X
1
0
0
1
0
0
1
1
0
1
X
1
DCEN
X
0
1
X
X
Timer/Counter 2 or (2) to output a 50% duty cycle clock ranging from
3.58Hz to 3.75MHz at a 30MHz operating frequency.
To configure the Timer/Counter 2 as a clock generator, bit C/T2 (in
T2CON) must be cleared and bit T20E in T2MOD must be set. Bit
TR2 (T2CON.2) also must be set to start the timer.
The Clock-Out frequency depends on the oscillator frequency and
the reload value of Timer 2 capture registers (TCAP2H, TCAP2L) as
shown in this equation:
TCLK
2 (65536 * TCAP2H, TCAP2L)
In the Clock-Out mode Timer 2 roll-overs will not generate an
interrupt. This is similar to when it is used as a baud-rate generator.
It is possible to use Timer 2 as a baud-rate generator and a clock
generator simultaneously. Note, however, that the baud-rate will be
1/8 of the Clock-Out frequency.
MODE
Timer off (stopped)
16-bit auto-reload, counting up
16-bit auto-reload, counting up or down depending on T2EX pin
16-bit capture
Baud rate generator
TSTAT
Address:411
Bit Addressable
Reset Value: 00H
MSB
LSB
—
—
—
—
— T1OE — T0OE
BIT
TSTAT.2
TSTAT.0
SYMBOL
T1OE
T0OE
FUNCTION
When 0, this bit allows the T1 pin to clock Timer 1 when in the counter mode.
When 1, T1 acts as an output and toggles at every Timer 1 overflow.
When 0, this bit allows the T0 pin to clock Timer 0 when in the counter mode.
When 1, T0 acts as an output and toggles at every Timer 0 overflow.
SU00612B
Figure 9. Timer 0 And 1 Extended Status (TSTAT)
T2MOD
Address:419
Bit Addressable
Reset Value: 00H
MSB
—
— RCLK1 TCLK1 —
LSB
— T2OE DCEN
BIT
T2MOD.5
T2MOD.4
T2MOD.1
T2MOD.0
SYMBOL
RCLK1
TCLK1
T2OE
DCEN
FUNCTION
Receive Clock Flag.
Transmit Clock Flag. RCLK1 and TCLK1 are used to select Timer 2 overflow rate as a clock source
for UART1 instead of Timer T1.
When 0, this bit allows the T2 pin to clock Timer 2 when in the counter mode.
When 1, T2 acts as an output and toggles at every Timer 2 overflow.
Controls count direction for Timer 2 in autoreload mode.
DCEN=0 counter set to count up only
DCEN=1 counter set to count up or down, depending on T2EX (see text).
SU00610B
Figure 10. Timer 2 Mode Control (T2MOD)
2002 Mar 13
22