IC-MG Datasheet, PDF (10/20 Pages) IC-Haus GmbH – 8-Bit Sin/Cos INTERPOLATION IC WITH RS422 DRIVER

iC-MG
preliminary
8-Bit Sin/Cos INTERPOLATION IC WITH RS422 DRIVER
SERIAL EEPROM INTERFACE
Rev C1, Page 10/20
The serial configuration interface consists of the two
pins SCL and SDA and enables read access to a se-
rial EEPROM (requirements: 1 Kbit, 128x8, 3.3 V to
5 V operation, device address 0x50 "1010 000"; rec-
ommended: Atmel AT24C01B; notes: devices ignoring
A2...0 address bit settings are not suitable).
Once the supply has been switched on (power down
reset) iC-MG reads the configuration from the EEP-
ROM which has the device ID 0x50. Bit errors in the
0x00 to 0x2F memory area are monitored by the CRC
deposited in register CHKSUM (see program example;
the polynomial used is "1 0001 1101"). Should an error
occur while the data is being read in the readin pro-
cess is repeated; the system aborts following a fourth
faulty attempt and tristates the output drivers.
As an alternative to the power down reset iC-MG can
be triggered to again read in the configuration via pin
NERR. To this end pin voltage V(NERR) must initially
exceed threshold voltage VTMon (see Electrical Char-
acteristics). Once the pin voltage has dropped to be-
low VTMon iC-MG starts communicating with the EEP-
ROM. The device ID stored in register DEVID is used
to address the EEPROM.
Example of CRC Calculation Routine
unsigned char ucDataStream = 0;
i n t iCRCPoly = 0x11D ;
unsigned char ucCRC=0;
int i = 0;
ucCRC = 1 ; / / s t a r t v a l u e ! ! !
for ( iReg = 0; iReg <47; iReg ++)
{
ucDataStream = ucGetValue ( iReg ) ;
for ( i =0; i <=7; i ++) {
i f ( ( ucCRC & 0x80 ) ! = ( ucDataStream & 0x80 ) )
ucCRC = (ucCRC << 1 ) ^ iCRCPoly ;
else
ucCRC = (ucCRC << 1 ) ;
ucDataStream = ucDataStream << 1 ;
}
}