PIC24FJ64GA002-I/SO Microchip Technology Inc., PIC24FJ64GA002-I/SO Datasheet - Page 185

• Manufacturer Part Number: PIC24FJ64GA002-I/SO
• Description: MCU, 16-Bit, 28-Pin, 64KB Flash, 8KB RAM, 21 I/O, Nanowatt
• Manufacturer: Microchip Technology Inc.

Specifications of PIC24FJ64GA002-I/SO

• A/d Inputs: 10 Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 16 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 21
• Interface: I2C/SPI/UART
• Memory Capacity: 64 Kbytes
• Memory Type: Flash
• Number Of Bits: 16
• Number Of Inputs: 21
• Number Of Pins: 28
• Package Type: 28-pin SOIC
• Programmable Memory: 64K Bytes
• Ram Size: 8K Bytes
• Speed: 32 MHz
• Timers: 5-16-bit
• Voltage, Range: 2-3.6 V
• Voltage, Rating: 2-3.6 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

19.2
The module implements a software configurable CRC
generator. The terms of the polynomial and its length
can be programmed using the CRCXOR (X<15:1>) bits
and the CRCCON (PLEN3:PLEN0) bits, respectively.
Consider the CRC equation:
To program this polynomial into the CRC generator,
the CRC register bits should be set as shown in
Table 19-1.
FIGURE 19-1:
© 2007 Microchip Technology Inc.
D
PLEN<3:0>
OUT
XOR
Overview
IN
p_clk
BIT 0
Hold
OUT
x
16
0
+ x
CRC SHIFTER DETAILS
12
+ x
5
X1
0
1
+ 1
IN
p_clk
BIT 1
Hold
OUT
1
PIC24FJ64GA004 FAMILY
Preliminary
CRC Shift Register
X2
0
1
CRC Write Bus
TABLE 19-1:
Note that for the value of X<15:1>, the 12th bit and the
5th bit are set to ‘1’, as required by the equation. The
0th bit required by the equation is always XORed. For
a 16-bit polynomial, the 16th bit is also always
assumed to be XORed; therefore, the X<15:1> bits do
not have the 0th bit or the 16th bit.
The topology of a standard CRC generator is shown in
Figure 19-2.
IN
PLEN3:PLEN0
p_clk
Hold
BIT 2
OUT
Bit Name
X<15:1>
2
CRC Read Bus
EXAMPLE CRC SETUP
X3
0
1
X15
000100000010000
0
1
Bit Value
IN
BIT 15
1111
p_clk
Hold
DS39881B-page 183
OUT
15