ADUC7032BSTZ-88-RL Analog Devices Inc, ADUC7032BSTZ-88-RL Datasheet - Page 65

• Manufacturer Part Number: ADUC7032BSTZ-88-RL
• Description: Flash 96k ARM7 TRIPLE 16-Bit ADC LIN IC.
• Manufacturer: Analog Devices Inc
• Series: MicroConverter® ADuC7xxxr

Specifications of ADUC7032BSTZ-88-RL

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 20.48MHz
• Connectivity: LIN, SPI, UART/USART
• Peripherals: POR, PSM, Temp Sensor, WDT
• Number Of I /o: 9
• Program Memory Size: 96KB (96K x 8)
• Program Memory Type: FLASH
• Eeprom Size: -
• Ram Size: 6K x 8
• Voltage - Supply (vcc/vdd): 3.5 V ~ 18 V
• Data Converters: A/D 2x16b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 48-LQFP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

ADUC7032-8L LOW POWER CLOCK CALIBRATION
The low power 131 kHz oscillator can be calibrated using either
the precision 131 kHz oscillator or an external 32.768 kHz
watch crystal. Two dedicated calibration counters and an oscil-
lator trim register are used to implement this feature.
One counter, nine bits wide, is clocked by either the precision
oscillator or the external watch crystal. The second counter, 10
bits wide, is clocked by the low power oscillator, either directly
at 131 kHz or via a divide-by-4 block generating 32.768 kHz.
The source for each calibration counter should be of the same
frequency. The trim register (OSC0TRM) is an 8-bit wide
register, the lower four bits of which are user-accessible trim
bits. Increasing the value in OSCT0RM decreases the frequency
of the low power oscillator; decreasing the value increases the
frequency. Based on a nominal frequency of 131 kHz, the typical
trim range is 127 kHz to 135 kHz.
The clock calibration mode is configured and controlled by the
following MMRs:
•
•
•
•
•
An example calibration routine is shown in Figure 28. User code
configures and enables the calibration sequence via OSC0CON.
When the precision oscillator calibration counter, OSC0VAL0,
reaches 0x1FF, both counters are disabled.
User code then reads back the value of the low power oscillator
calibration counter. There are three possible scenarios.
•
•
•
When the OSC0TRM has been changed, the routine should be
rerun and the new frequency checked.
OSC0CON: control bits for calibration
OSC0STA: calibration status register
OSC0VAL0: 9-bit counter, Counter 0
OSC0VAL1: 10-bit counter, Counter 1
OSC0TRM: oscillator trim register
OSC0VAL0 = OSC0VAL1: No further action is required.
OSC0VAL0 > OSC0VAL1: The low power oscillator is
running slow. OSC0TRM must be decreased.
OSC0VAL0 < OSC0VAL1: The low power oscillator is
running fast. OSC0TRM must be increased.
Rev. A | Page 65 of 120
Using the internal precision 131 kHz oscillator, it takes
approximately 4 ms to execute the calibration routine. If the
external 32.768 kHz crystal is used, the time increases to 16 ms.
Note that prior to the clock calibration routine being started,
it is required that the user switch to either the precision 131 kHz
oscillator or the external 32.768 kHz watch crystal as the PLL
clock source. If this is not done, the PLL may lose lock each
time OSC0TRM is modified. This increases the length of time it
takes to calibrate the low power oscillator.
OSC0VAL0 < OSC0VAL1
Figure 28. Example OSC0TRM Calibration Routine
INCREASE
OSC0TRM
NO
OSC0VAL0 = OSC0VAL1
IS ERROR WITHIN
DESIRED LEVEL?
OSC0STA[0] = 1
CALIBRATION
CALIBRATION
ROUTINE
ROUTINE
BEGIN
WHILE
END
YES
OSC0VAL0 > OSC0VAL1
DECREASE
OSC0TRM
ADuC7032-8L