ADUC7039BCP6Z-RL Analog Devices Inc, ADUC7039BCP6Z-RL Datasheet - Page 53

• Manufacturer Part Number: ADUC7039BCP6Z-RL
• Description: Flash 64k ARM7 Dual 16-Bit ADC LIN I.C.
• Manufacturer: Analog Devices Inc
• Series: MicroConverter® ADuC7xxxr

Specifications of ADUC7039BCP6Z-RL

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 20.48MHz
• Connectivity: LIN, SPI
• Peripherals: POR, Temp Sensor, WDT
• Number Of I /o: 6
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3.5 V ~ 18 V
• Data Converters: A/D 2x16b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 115°C
• Package / Case: 32-LFCSP
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption
• Eeprom Size: -
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption

OSCILLATORS CALIBRATION
The ADuC7039 features two oscillators and two calibration
schemes:
•
•
Each oscillator has dedicated calibration MMRs:
•
•
•
•
Initial Low Power Oscillator Calibration
After reset, the low power oscillator is running at a frequency
of 128 kHz with a maximum error of −10% to +3% from the
center frequency of 128 kHz. An end-of-line calibration at
the customer production line must be run within a given
temperature range of 25°C ± 5°C to center the low power
oscillator on the precision oscillator. Once calibrated, the low
power oscillator stays within ±3% of the center frequency.
This initial calibration only needs to be run once, at end-of-line.
Further calibration can be performed in user code to compen-
sate for temperature drift of the low power oscillator.
Low Power Oscillator Calibration Sequence
The low power 128 kHz oscillator can be calibrated using the
precision 128 kHz oscillator. Two dedicated calibration counters
are used to implement this feature.
One counter, 9-bits wide, is clocked by the precision oscillator.
The second counter, 10-bits wide, is clocked by the low power
The low power oscillator can be calibrated from the
precision oscillator or from the LIN communication.
The trim value can also be modified by user code.
The precision oscillator can be calibrated from the LIN
communication. The trim value can also be modified
by user code.
LOCUSR0 is the low power oscillator user trim register. It
is a 8-bit wide register. Increasing the value in LOCUSR0
decreases the frequency of the low power oscillator;
decreasing the value increases the frequency. Based on a
nominal frequency of 128 kHz, the typical trim range is
between 103 kHz to 156 kHz. This MMR can be written
directly by user code or changed automatically by the
hardware relative to the LIN baud rate.
LOCUSR1 is the precision oscillator user trim register.
This is a 10-bit wide MMR. Increasing the value in
LOCUSR1 decreases the frequency of the precision
oscillator; decreasing the value increases the frequency.
Based on a nominal frequency of 128 kHz, the typical
trim range is between 94 kHz to 178 kHz. This MMR can
be written directly by user code, or changed automatically
by the hardware relative to the LIN baud rate.
LOCVAL0 is an 8-bit, read-only MMR and displays the
current trim value of the low power oscillator.
LOCVAL1 is a 10-bit, read-only MMR and displays the
current trim value of the precision oscillator. Note that
11 bits can be read from this register but only 10 are used
for calibration.
Rev. B | Page 53 of 92
oscillator. The clock calibration mode is configured and
controlled by the following MMRs:
•
•
•
•
An example calibration routine is shown in Figure 21. User
code configures and enables the calibration sequence using
OSCCON. When the precision oscillator calibration counter,
OSCVAL0, 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 LOCUSR0 has been changed, the routine should
be run again and the new frequency checked. Note that the
LOCUSR0 MMR is key protected. The value 0x1324 must
be written in LOCKEY prior to writing LOCUSR0.
Using the internal, precision oscillator, it takes approximately
4 ms to execute the calibration routine.
Prior to the clock calibration routine being started, it is required
that the user switch to the precision oscillator to serve as the
PLL clock source, otherwise, the PLL can lose lock each time
LOCUSR0 is modified. This increases the length of time it
takes to calibrate the low power oscillator.
OSCCON—control bits for calibration.
OSCSTA—calibration status register.
OSCVAL0—9-bit counter, Counter 0.
OSCVAL1—10-bit counter, Counter 1.
OSCVAL0 = OSCVAL1. No further action is required.
OSCVAL0 > OSCVAL1. The low power oscillator is
running slow. LOCUSR0 must be decreased.
OSCVAL0 < OSCVAL1. The low power oscillator is
running fast. LOCUSR0 must be increased.
OSC0VAL0 < OSC0VAL1
INCREASE
LOCUSR0
Figure 21. OSCTRM Calibration Routine
NO
OSC0VAL0 = OSC0VAL1
IS ERROR WITHIN
DESIRED LEVEL?
CALIBRATION
CALIBRATION
INTERRUPT
WAIT FOR
ROUTINE
ROUTINE
BEGIN
END
YES
OSC0VAL0 > OSC0VAL1
DECREASE
LOCUSR0
ADuC7039