PIC24FJ64GA004-I/ML Microchip Technology, PIC24FJ64GA004-I/ML Datasheet - Page 2

• Manufacturer Part Number: PIC24FJ64GA004-I/ML
• Description: IC PIC MCU FLASH 21KX24 44QFN
• Manufacturer: Microchip Technology
• Series: PIC® 24Fr

Specifications of PIC24FJ64GA004-I/ML

• Program Memory Type: FLASH
• Program Memory Size: 64KB (22K x 24)
• Package / Case: 44-QFN
• Core Processor: PIC
• Core Size: 16-Bit
• Speed: 32MHz
• Connectivity: I²C, PMP, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 35
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 3.6 V
• Data Converters: A/D 13x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC24FJ
• Core: PIC
• Data Bus Width: 16 bit
• Data Ram Size: 8 KB
• Interface Type: I2C/IrDA/SPI/UART
• Maximum Clock Frequency: 32 MHz
• Number Of Programmable I/os: 35
• Number Of Timers: 5
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52713-733, 52714-737, 53276-922, EWDSPIC
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, DM240011, DM300027, DV164033, MA240013, AC164127, DM240002
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 13-ch x 10-bit
• Controller Family/series: PIC24
• No. Of I/o's: 35
• Ram Memory Size: 8KB
• Cpu Speed: 32MHz
• No. Of Timers: 5
• Embedded Interface Type: I2C, SPI, UART
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 876-1004 - PIC24 BREAKOUT BOARDDM240011 - KIT STARTER MPLAB FOR PIC24F MCUAC162088 - HEADER MPLAB ICD2 24FJ64GA004 28AC164336 - MODULE SOCKET FOR PM3 28/44QFNDV164033 - KIT START EXPLORER 16 MPLAB ICD2
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC24F Family Reference Manual
30.1
DS39714A-page 30-2
INTRODUCTION
The programmable Cyclic Redundancy Check (CRC) module in PIC24F devices is a software
configurable CRC checksum generator. The checksum is a unique number associated with a
message or a particular block of data containing several bytes. Whether it is a data packet for
communication, or a block of data stored in memory, a piece of information like checksum helps
to validate it before processing. The simplest way to calculate a checksum is to add together all
the data bytes present in the message. However, this method of checksum calculation fails badly
when the message is modified by inverting or swapping groups of bytes. Also, it fails when null
bytes are added anywhere in the message.
The CRC is a more complicated, but robust, error checking algorithm. The main idea behind the
CRC algorithm is to treat a message as a binary bit stream and divide it by a fixed binary number.
The remainder from this division is considered as the checksum. Like in division, the CRC
calculation is also an iterative process. The only difference is that these operations are done on
modulo arithmetic based on mod2. For example, division is replaced with the XOR operation (i.e.,
subtraction without carry). The CRC algorithm uses the term polynomial to perform all of its cal-
culations. The divisor, dividend and remainder that are represented by numbers are termed as
polynomials with binary coefficients. For example, the number, 25h (11001), is represented as:
Equation 30-1:
In order to perform the CRC calculation, a suitable divisor is first selected. This divisor is called
the generator polynomial. Since CRC is used to detect errors, a suitable generator polynomial of
suitable length needs to be chosen for a given application, as each polynomial has different error
detection capabilities. Some polynomials are widely used for many applications, but the error
detecting capabilities of any particular polynomial are beyond the scope of this reference chapter.
The CRC calculation is an iterative process and consumes considerable CPU bandwidth when
implemented in software. The software configurable CRC hardware module in PIC24F devices
facilitates a fast CRC checksum calculation with minimal software overhead.
The primary features of the programmable CRC module are:
• Programmable bit length for the CRC generator polynomial (up to 16-bit length)
• Programmable CRC generator polynomial
• Interrupt output
• 8-deep, 16-bit or 16-deep, 8-bit FIFO for data input
(1 * x4) + (1 * x3) + (0 * x2) + (0 * x1) + (1* x0), or x4 + x3 + x0
Advance Information
© 2006 Microchip Technology Inc.