Questions tagged [crc]

CRC, or Cyclic Redundancy Check, is a technique commonly used to detect accidental changes to data

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Append calculated CRC to data and recalculate does not yield zero

I have been working on understanding CRC calculations for implementation in VHDL. Specifically I have implemented the CRC-32C (polynomial = 0x1EDC6F41) a couple of ways. First using an LFSR approach ...
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CRC in CAN Messages

I would like to know the difference between CRC calculation in CAN physical layer vs CRC calculation in the application layer. How does the CRC calculation in these layers affect the ASIL (Automobile ...
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183 views

Calculate CRC-16/Maxim in VHDL

I try to do a CRC-16/Maxim calculation in VHDL. My current implementation looks as follows ...
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1answer
86 views

Revising CRC value after data adjustment

I have a 181 bytes data stream with 4 bytes CRC32 value at the end. The entire message length is 185 bytes. The data stream is stored in the FPGA onchip memory and waiting to put into wire by TCP. ...
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107 views

CRC generator polynomial for data flash memory storage

I have been facing a problem how to implement embedded software configuration parameters management system. It means how to implement a software module which will be responsible for storage of for ...
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89 views

Incorrect ethernet crc code

I am trying to use the ethernet phy on my FPGA. I am at the point where I can receive a frame. The frame I can see using chipscope matches the data of the frame sent from my computer which I can ...
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1answer
114 views

Calculating number of errors that is undetected by a CRC using a particular polynomial

My goal is to determine optimal generator polynomial and size of the Frame Check Sequence (CRC field) for protocol that I am developing. Reading the paper, "Cyclic Redundacy Code (CRC) Polynomial ...
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1answer
538 views

CRC hardware implementation

What is the difference between these two implementations as the feedback is in first implementation the last reg only but the second implementation last reg xored with the input bit, so, what is the ...
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1answer
570 views

Verilog parallel CRC with arbitrary polynomial

for my next project I need to implement a CRC IP core in Verilog HDL. It must use 16bit polynomial and 16bit CRC result register. Data is being fed into it in 8bit chuncks / bytes. I have allready ...
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1k views

How is crc5 calculated for a usb token?

I captured the usb packets on a usb1.1 mouse using a generic 24mhz logic analyzer. here is the sigrok capture for the first token. as per the usb docs.. a CRC5 is calculated for the token by taking ...
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1answer
247 views

How does the rollback work in a FIFO?

From reading the book titled "Advanced Chip Design practical examples by verilog", I faced some questions about when the Ethernet packet is read from the FIFO and how the rollback works for the ...
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389 views

C++ - Help Interpreting the instructions of a CRC error-checking programming assignment

This is unconventional, based on what I've seen, but I can't get a hold of my professor's aides to clarify this assignment. I hope this is still ok to post here. I would greatly appreciate some help ...
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645 views

CRC implementation for ethernet

With an example for data with a hexadecimal value of 0xda and a polynomial 0x07, I would find the CRC as follows (using the ...
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2answers
2k views

How to use the data CRC of SD cards in SPI mode?

I am interfacing an SD card through SPI using an AVR microcontroller (more specifically it is the Uzebox console). I can successfully initialize the card with turning CRC check ON with CMD59 (so I ...
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SENT CRC calculation

I am using SENT protocol in my project. In my SENT implementation, the data nibbles are 3. So 12 bit data, including a status nibble and CRC nibble. I need to calculate the CRC for 3 data nibbles. ...
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Help identifying checksum

I need help identifying the checksum algorithm in the following packets please. So, packets format is: sd ?? dd dd dd ?? where s = start nibble d = data (binary coded decimal) ? = unknown - ...
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194 views

Best value to overwrite old to tell if memory is not used on eeprom

I have an EEPROM I want to store CRC32 hashes on between 0x0000 and 0x008C. In this range I need a way that I can erase one of the hashes and overwrite its bytes to a default number. By doing this I ...
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Understanding IR Protocol Checksum generation

To control my AC with an Arduino, I'm trying to emulate the IR Remote. Not with another IR LED, but directly connected to the IR Receivers Signal wire on the board. Using the Arduino as a Logic ...
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2answers
657 views

How to get up to 24 I/O pins from the PIC4550

Im trying to implement and understand the CRC by making a circuit, by using 1 byte (8 bits), and a highest power of the polynomial of four, these 2 values should be XORed until i get a final output, ...
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2answers
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FCS verification of ethernet frame

i am trying to transmit a Ethernet frame from fpga to pc. my udp frame is: ...
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910 views

CRC32 on SAM D20 (Cortex M0+)

I've been having a hard time debugging the DSU module on a SAM D20 (datasheet). I mean to utilize it to calculate CRC32 for a program I'm uploading through a custom bootloader (bootloader not mine). ...
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1answer
160 views

Parallel-In-Serial-Out with Parity?

Can someone recommend a shift register IC with integrated parity or CRC generator? Is there such a thing anyway?
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471 views

Help reverse engineering a CRC-8 [closed]

I have an arduino based home temperature monitoring system using Ambient Weather F007th wireless Thermo-Hygrometers as sensors. I am trying to work out the CRC and add some code to my project to ...
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1answer
320 views

CRC/Parity/Hamming Protect 16-bit parallel bus

I've got a Cortex-M4 based MCU linked to a FPGA via a 16-bit parallel memory bus interface. In essence the FPGA behaves like an external memory mapped to the memory space of the MCU: the MCU presents ...
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1answer
440 views

CRC polynomial and Parity Error detection

My question is about the CRC generator polynomial. If I have a generator of level 5, say: $$X^5+X^4+X^2+1$$ How can I know if it can or cannot detect a parity error? Also how can I know the error ...
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2answers
356 views

Finding an input sequence given a generating polynomial and CRC

I am working on a circuit that inputs a 31-bit pseudo-random binary string into a CCITT CRC-16 block which generates a 16-bit CRC output. I know that M(x)/G(x) = Q(x) + R(x) and the transmitted code ...
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3answers
1k views

Reverse-engineering IR check bits/CRC

I'm trying to build a simple Arduino-based IR remote control for a cheap toy IR-controlled helicopter (same as this one - it's called "Diamond Gyro" or "Diamond Force"). I've decoded the IR protocol ...
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2answers
1k views

My CRC8 is dysfunctional and I'm not sure why!

So I'm interfacing an arduino with a Melexis temperature sensor, and it's going okay--aside from the fact that I can't seem to get the CRC check to work. I've gotten read operations to complete ...
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2answers
5k views

Implementing parallel CRC in verilog

I am trying to implement a parallel CRC in Verilog but having trouble getting it to work. This is a snippet of the code that I'm having trouble with. ...
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1answer
749 views

What is the purpose of CRC_IDR in STM32 processors?

The STM32's CRC calculation unit has a register named CRC_IDR. This 32 bit register allows the user to store 8bits of data. There seems to be no link between this register and rest of the CRC ...
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2answers
4k views

CRC for eeprom data check

I wanted to check redundancy in eeprom and crosscheck the data for any errors occurred or not and I ended up reading CRC code. I found it useful but have some doubts that need clarity. My objective ...
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2answers
2k views

EEPROM data check

I am communicating with an EEPROM chip with micro controller. I am writing certain data in to specific addresses in EEPROM and needs to check the data occasionally. But I have no idea other than ...
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2answers
3k views

How can I implement Bluetooth Low Energy CRC in 24 bits?

According to the Bluetooth Core 4.0 specification, the Bluetooth Low Energy air packet has a 24-bit CRC with the following polynomial: ...
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3answers
1k views

Why is the data output of some ICs in two's complement form?

I've been looking into some ICs now. Some of them have the calculated result (data) in twos complement form, placed in register to be read by other IC. What is the logic behind converting the data to ...
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2answers
38k views

Calculating a simple CRC

In the datasheet for the ET1200 EtherCAT ASIC (page 94), I am told that I need to calculate a CRC of some of the 16-bit data in its EEPROM. The only description of this CRC is: Low byte [of word 7] ...
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2answers
1k views

What's the correct form of this CRC algorithm

We are working on communication between AVR and a Crous PTZ. We found its protocol and now we can turn it on and so. We have problem with its CRC. This is Crous protocol doc (Got it here), at end of ...
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1answer
3k views

CRC-16 Calculation

I'm trying to calculate the CRC-16 in hex form using a seed of 0x0000. For your convenience, here's the polynomial for CRC-16 \$ x^{16} + x^{15} + x^2 + 1 \$ I have the following packet sequence ...