F28M36P63C2ZWTQ datasheet(86/202 Pages) TI

86 / 202 page

F28M36P63B2, F28M36P63C2

F28M36P53B2, F28M36P53C2, F28M36P33B2, F28M36P33C2

SPRS825 – OCTOBER 2012

www.ti.com

2.19 µCRC Module

The µCRC module is part of the master subsystem. This module can be used by Cortex™-M3 software to

compute CRC on data and program, which are stored at memory locations that are addressable by

Cortex™-M3. On this device, the Cortex™-M3 Flash Bank and ROM are mapped to the code space that is

only accessed by the ICODE/DCODE bus of Cortex™-M3; and RAMs are mapped on the SRAM space

that is accessible by the SYSTEM bus. Hence, the µCRC module snoops both the DCODE and SYSTEM

buses to support CRC calculation for data and program.

2.19.1 Functional Description

The µCRC module snoops both the DCODE and SYSTEM buses to support CRC calculation for data and

program. To allow interrupts execution in between CRC calculations for a block of data and to discard the

Cortex™-M3 literal pool accesses in between executions of the program (which reads data for CRC

calculation), the Cortex™-M3 ROM, Flash, and RAMs are mapped to a mirrored memory location. The

µCRC module grabs data from the bus to calculate CRC only if the address of the read data belongs to

mirrored memory space. After grabbing, the µCRC module performs the CRC calculation on the grabbed

data and updates the µCRC Result Register (µCRCRES). This register can be read at any time to get the

calculated CRC for all the previous read data. The µCRC module only supports CRC calculation for byte

accesses. So, in order to calculate the CRC on a block of data, software must perform byte accesses to

all the data. For half-word and word accesses, the µCRC module discards the data and does not update

the µCRCRES register.

NOTE

If a read to a mirrored address space is thrown from the debugger (Code Composer Studio

or any other debug platform), the µCRC module ignores the read data and does not update

the CRC result for that particular read.

2.19.2 CRC Polynomials

The following are the CRC polynomials that are supported by the µCRC module:

•

CRC8 Polynomial = 0x07

•

CRC16 Polynomial-1 = 0x8005

•

CRC16 Polynomial-2 = 0x1021

•

CRC32 Polynomial = 0x04C11DB7

2.19.3 CRC Calculation Procedure

The software procedure for calculating CRC for a set of data that is stored in Cortex™-M3 addressable

memory space is as follows:

1. Save the current value of the µCRC Result Register (µCRCRES) into the stack to allow calculation of

CRC in nested interrupt

2. Clear the µCRC Result Register (µCRCRES) by setting the CLEAR field of the µCRC Control Register

(µCRCCONTROL) to "1"

3. Configure the µCRC polynomials (CRC8, CRC16-P1, CRC16-P2, or CRC32) in the µCRC

Configuration Register (µCRCCONFIG)

4. Read the data from memory locations for which CRC needs to be calculated using mirrored address

5. Read the µCRCRES register to get the calculated CRC value. Pop the last saved value of the CRC

from the stack and store this value into the µCRC Result Register (uCRCRES)

Device Overview

Submit Documentation Feedback

F28M36P63C2ZWTQ Datasheet(PDF) 86 Page - Texas Instruments

F28M36P63C2ZWTQ Datasheet(HTML) 86 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL