PIC24FJ64GA106-I/MR Microchip Technology, PIC24FJ64GA106-I/MR Datasheet - Page 219

• Manufacturer Part Number: PIC24FJ64GA106-I/MR
• Description: 16-bit, 16 MIPS, 64KB Flash, 16Kb RAM, 84 I/O, NanoWatt 64 QFN 9x9x0.9mm TUBE
• Manufacturer: Microchip Technology
• Series: PIC® 24Fr

Specifications of PIC24FJ64GA106-I/MR

• Core Processor: PIC
• Core Size: 16-Bit
• Speed: 32MHz
• Connectivity: I²C, IrDA, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 64KB (22K x 24)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 3.6 V
• Data Converters: A/D 16x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VFQFN Exposed Pad
• Processor Series: PIC24FJ256GA110
• Core: PIC
• Data Bus Width: 16 bit
• Data Ram Size: 16 KB
• Interface Type: UART, I2C, SPI
• Maximum Clock Frequency: 8 MHz
• Number Of Timers: 5
• Operating Supply Voltage: 3.6 V
• Maximum Operating Temperature: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

REGISTER 19-10: ALMINSEC: ALARM MINUTES AND SECONDS VALUE REGISTER
19.2
The real-time crystal input can be calibrated using the
periodic auto-adjust feature. When properly calibrated,
the RTCC can provide an error of less than 3 seconds
per month. This is accomplished by finding the number
of error clock pulses for one minute and storing the
value into the lower half of the RCFGCAL register. The
8-bit signed value loaded into the lower half of
RCFGCAL is multiplied by four and will be either added
or subtracted from the RTCC timer, once every minute.
Refer to the steps below for RTCC calibration:
1.
2.
EQUATION 19-1:
 2010 Microchip Technology Inc.
bit 15
bit 7
Legend:
R = Readable bit
-n = Value at POR
bit 15
bit 14-12
bit 11-8
bit 7
bit 6-4
bit 3-0
Error (Clocks per Minute) = (Ideal Frequency† –
Measured Frequency) * 60 = Clocks per Minute
Using another timer resource on the device, the
user must find the error of the 32.768 kHz
crystal.
Once the error is known, it must be converted to
the number of error clock pulses per minute and
loaded into the RCFGCAL register.
U-0
U-0
—
—
Calibration
† Ideal frequency = 32,768 Hz
Unimplemented: Read as ‘0’
MINTEN<2:0>: Binary Coded Decimal Value of Minute’s Tens Digit bits
Contains a value from 0 to 5.
MINONE<3:0>: Binary Coded Decimal Value of Minute’s Ones Digit bits
Contains a value from 0 to 9.
Unimplemented: Read as ‘0’
SECTEN<2:0>: Binary Coded Decimal Value of Second’s Tens Digit bits
Contains a value from 0 to 5.
SECONE<3:0>: Binary Coded Decimal Value of Second’s Ones Digit bits
Contains a value from 0 to 9.
SECTEN2
MINTEN2
R/W-x
R/W-x
RTCC CALIBRATION
W = Writable bit
‘1’ = Bit is set
SECTEN1
MINTEN1
R/W-x
R/W-x
SECTEN0
MINTEN0
PIC24FJ256GA110 FAMILY
R/W-x
R/W-x
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
SECONE3
MINONE3
R/W-x
R/W-x
3.
4.
Writes to the lower half of the RCFGCAL register
should only occur when the timer is turned off, or
immediately after the rising edge of the seconds pulse.
Note:
a) If the oscillator is faster then ideal (negative
result form Step 2), the RCFGCAL register value
needs to be negative. This causes the specified
number of clock pulses to be subtracted from
the timer counter once every minute.
b) If the oscillator is slower then ideal (positive
result from Step 2) the RCFGCAL register value
needs to be positive. This causes the specified
number of clock pulses to be added from the
timer counter once every minute.
Divide the number of error clocks per minute by
4 to get the correct CAL value and load the
RCFGCAL register with the correct value.
(Each 1-bit increment in CAL adds or subtracts
4 pulses.)
It is up to the user to include in the error
value the initial error of the crystal, drift
due to temperature and drift due to crystal
aging.
SECONE2
MINONE2
R/W-x
R/W-x
x = Bit is unknown
SECONE1
MINONE1
R/W-x
R/W-x
DS39905E-page 219
SECONE0
MINONE0
R/W-x
R/W-x
bit 8
bit 0