PXAS37KBA,512 NXP Semiconductors, PXAS37KBA,512 Datasheet - Page 26

IC XA MCU 16BIT 32K OTP 68-PLCC

PXAS37KBA,512

Manufacturer Part Number
PXAS37KBA,512
Description
IC XA MCU 16BIT 32K OTP 68-PLCC
Manufacturer
NXP Semiconductors
Series
XAr
Datasheet

Specifications of PXAS37KBA,512

Core Processor
XA
Core Size
16-Bit
Speed
30MHz
Connectivity
EBI/EMI, I²C, UART/USART
Peripherals
PWM, WDT
Number Of I /o
50
Program Memory Size
32KB (32K x 8)
Program Memory Type
OTP
Ram Size
1K x 8
Voltage - Supply (vcc/vdd)
2.7 V ~ 5.5 V
Data Converters
A/D 8x8b
Oscillator Type
External
Operating Temperature
0°C ~ 70°C
Package / Case
68-PLCC
Processor Series
PXAS3x
Core
80C51
Data Bus Width
16 bit
Data Ram Size
1 KB
Interface Type
I2C, UART
Maximum Clock Frequency
30 MHz
Number Of Programmable I/os
50
Number Of Timers
3
Operating Supply Voltage
2.7 V to 5.5 V
Maximum Operating Temperature
+ 70 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
0 C
On-chip Adc
8 bit, 8 Channel
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Eeprom Size
-
Lead Free Status / Rohs Status
 Details
Other names
568-3536-5
935262377512
PXAS37KBA

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Quantity
Price
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Philips Semiconductors
PCA Watchdog Timer
An on-board watchdog timer is available with the PCA to improve
the reliability of the system without increasing chip count. Watchdog
timers are useful for systems that are susceptible to noise, power
glitches, or electrostatic discharge. Module 4 is the only PCA
module that can be programmed as a watchdog. However, this
module can still be used for other modes if the watchdog is not
needed.
Figure 18 shows a diagram of how the watchdog works. The user
pre-loads a 16-bit value in the compare registers. Just like the other
compare modes, this 16-bit value is compared to the PCA timer
value. If a match is allowed to occur, an internal reset will be
generated. This will not cause the RST pin to be driven low.
In order to hold off the reset, the user has three options:
1. periodically change the compare value so it will never match the
2. periodically change the PCA timer value so it will never match
3. disable the watchdog by clearing the WDTE bit before a match
2000 Dec 01
XA 16-bit microcontroller
32 K/1 K OTP/ROM/ROMless, 8-channel 8-bit A/D, low voltage (2.7 V–5.5 V),
I
2
PCA timer,
the compare values, or
occurs and then re-enable it.
C, 2 UARTs, 16 MB address range
WRITE TO
CCAP4L
0
WRITE TO
CCAP4H
1
RESET
ENABLE
Figure 18. PCA Watchdog Timer m(Module 4 only)
CCAP4H
16–BIT COMPARATOR
CH
PCA TIMER/COUNTER
CIDL
––
ECOMn
WDTE
CCAP4L
CL
CAPPn
26
––
0
MODULE 4
PCA timer (CH,CL). This code is given in the WATCHDOG routine in
MATCH
The first two options are more reliable because the watchdog timer
is never disabled as in option #3. If the program counter ever goes
astray, a match will eventually occur and cause an internal reset.
The second option is also not recommended if other PCA modules
are being used. Remember, the PCA timer is the time base for all
modules; changing the time base for other modules would not be a
good idea. Thus, in most applications the first solution is the best
option.
Figure 19 shows the code for initializing the watchdog timer. Module
4 can be configured in either compare mode, and the WDTE bit in
CMOD must also be set. The user’s software then must periodically
change (CCAP4H,CCAP4L) to keep a match from occurring with the
Figure 19.
This routine should not be part of an interrupt service routine,
because if the program counter goes astray and gets stuck in an
infinite loop, interrupts will still be serviced and the watchdog will
keep getting reset. Thus, the purpose of the watchdog would be
defeated. Instead, call this subroutine from the main program within
2
16
CAPNn
count of the PCA timer.
––
0
MATn
––
1
TOGn
CPS1
X
CPS0
PWMn
0
ECCFn
ECF
X
Preliminary specification
CMOD
(490H)
RESET
CCAPM4
(495H)
SU01313
XA-S3