date

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PART NUMBER:

DESCRIPTION:

11/2010

7 of 7

Command 0x70: set_zero_point

This command sets the current position to zero or adjusts to the offset stored in comm_pos in the EEPROM and

saves this setting in the EEPROM. The host should send nop_a5 repeatedly after sending this command, the

response will be 0xa5 while update is proceeding and eeprom_wr is the response when update is finished. 0xF9 is

the location for the Low Byte of comm_pos and 0xF8 is the location for the High Byte of comm_pos.

Comand 0x80,<byte_address>,<data>: eeprom_wr

This command causes the data to be written to the address given in <byte_address>. The address can be 0x00 to

0x7f for 128 bytes of data.

Comand 0x90,<byte_address>,0x01: eeprom_rd

This command causes the data in eeprom at the given address to be read and put in the output fifo.

The sequence is as follows:

1) issue read command, receive idle character

2) issue NOP, receive idle character or 0x90 (echo of read command)

3) repeat step 2 if it is an idle character

4) issue NOP and receive

Commutation Alignment and setting the Zero point

To align the commutation angle with the encoder there are two steps:

1) Configure the encoder alignment angle using the Demo Board. The alignment angle is the angle relative to

U,V,W poles which is used for setting the encoder on the armature. The alignment angle is set at the same time

as several other parameters, and the encoder must be power cycled after configuration.

2) With the encoder mounted, position the rotor to the alignment angle and use the “zero” command on the demo

board to write the rotor position in non-volatile memory in the encoder. The encoder must be power cycled after

this operation, and it will use this offset at initialization every time at startup.

Note: the demo board allows setting the alignment angle between -180 and 180 degrees in increments of

5 degrees. 0 (zero) degrees corresponds to the rising edge of the U signal. The direction of rotation can also

be set.

phone 503.612.2300

fax 503.612.2380 www.cui.com

AMT303

COMMUTATION ENCODER