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ethercat
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Calculate checksum when writing EEPROM or alias address.

This commit is contained in:
Florian Pose 2007-09-19 09:37:01 +00:00
parent 3cdf084fdc
commit 0ef6a7360d
2 changed files with 69 additions and 7 deletions
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1
NEWS
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@ -6,6 +6,7 @@ $Id$
Changes in version 1.3.2:
* Calculate checksum when writing EEPROM or alias address.
* Removed config.kbuild and replaced Kbuild files by Kbuild.in files.
-------------------------------------------------------------------------------

75
master/slave.c
View File

@ -890,6 +890,46 @@ int ec_slave_schedule_eeprom_writing(ec_eeprom_write_request_t *request)
/*****************************************************************************/
/**
* Calculates the EEPROM checksum field.
*
* The checksum is generated with the polynom x^8+x^2+x+1 (0x07) and an
* initial value of 0xff (see IEC 61158-6-12 ch. 5.4).
*
* The below code was originally generated with PYCRC
* http://www.tty1.net/pycrc
*
* ./pycrc.py --width=8 --poly=0x07 --reflect-in=0 --xor-in=0xff
* --reflect-out=0 --xor-out=0 --generate c --algorithm=bit-by-bit
*
* \return CRC8
*/
uint8_t ec_slave_eeprom_crc(const uint8_t *data, size_t length)
{
unsigned int i;
uint8_t bit, byte, crc = 0x48;
while (length--) {
byte = *data++;
for (i = 0; i < 8; i++) {
bit = crc & 0x80;
crc = (crc << 1) | ((byte >> (7 - i)) & 0x01);
if (bit) crc ^= 0x07;
}
}
for (i = 0; i < 8; i++) {
bit = crc & 0x80;
crc <<= 1;
if (bit) crc ^= 0x07;
}
return crc;
}
/*****************************************************************************/
/**
* Writes complete EEPROM contents to a slave.
* \return data size written in case of success, otherwise error code.
@ -904,6 +944,7 @@ ssize_t ec_slave_write_eeprom(ec_slave_t *slave, /**< EtherCAT slave */
const uint16_t *cat_header;
uint16_t cat_type, cat_size;
int ret;
uint8_t crc;
if (slave->master->mode != EC_MASTER_MODE_IDLE) { // FIXME
EC_ERR("Writing EEPROMs only allowed in idle mode!\n");
@ -927,6 +968,12 @@ ssize_t ec_slave_write_eeprom(ec_slave_t *slave, /**< EtherCAT slave */
return -EINVAL;
}
// calculate checksum
crc = ec_slave_eeprom_crc(data, 14); // CRC over words 0 to 6
if (crc != data[14]) {
EC_WARN("EEPROM CRC incorrect. Must be 0x%02x.\n", crc);
}
cat_header = request.words + EC_FIRST_EEPROM_CATEGORY_OFFSET;
cat_type = EC_READ_U16(cat_header);
while (cat_type != 0xFFFF) { // cycle through categories
@ -964,11 +1011,12 @@ ssize_t ec_slave_write_alias(ec_slave_t *slave, /**< EtherCAT slave */
{
ec_eeprom_write_request_t request;
char *remainder;
uint16_t alias, word;
uint16_t alias, words[8];
int ret;
uint8_t crc;
if (slave->master->mode != EC_MASTER_MODE_IDLE) { // FIXME
EC_ERR("Writing EEPROMs only allowed in idle mode!\n");
EC_ERR("Writing to EEPROM is only allowed in idle mode!\n");
return -EBUSY;
}
@ -977,16 +1025,29 @@ ssize_t ec_slave_write_alias(ec_slave_t *slave, /**< EtherCAT slave */
EC_ERR("Invalid alias value! Dropping.\n");
return -EINVAL;
}
if (!slave->eeprom_data || slave->eeprom_size < 16) {
EC_ERR("Failed to read EEPROM contents from slave %u.\n",
slave->ring_position);
return -EINVAL;
}
// copy first 7 words of recent EEPROM contents
memcpy(words, slave->eeprom_data, 14);
// correct endianess
EC_WRITE_U16(&word, alias);
// write new alias address
EC_WRITE_U16(words + 4, alias);
// calculate new checksum over words 0 to 6
crc = ec_slave_eeprom_crc((const uint8_t *) words, 14);
EC_WRITE_U16(words + 7, crc);
// init EEPROM write request
INIT_LIST_HEAD(&request.list);
request.slave = slave;
request.words = &word;
request.offset = 0x0004;
request.size = 1;
request.words = words;
request.offset = 0x0000;
request.size = 8;
if ((ret = ec_slave_schedule_eeprom_writing(&request)))
return ret; // error code