SLOSE98A December 2022 – September 2023 DRV8461
PRODUCTION DATA
The DRV8461 features the INDEX registers to indicate the expected microstep current and position of the motor to the user.
CUR_A_POS register and CUR_A_SIGN bit indicate the position of coil A current in the indexer table.
CUR_B_POS register and CUR_B_SIGN bit indicate the position of coil B current in the indexer table.
CUR_A register indicates the value of expected coil A current, which is sin (90° x CUR_A_POS / 255).
Current will be positive if the corresponding sign bit is 1b and negative if the sign bit is 0b.
Table 7-12 shows the outputs of the CUR_A_POS and CUR_B_POS registers for a current waveform corresponding to 1/256 microstepping.
Current Quadrant | CUR_A_POS | CUR_A_SIGN | CUR_B | CUR_B_SIGN |
---|---|---|---|---|
First (0° -> 90°) | 0 -> 255 | 1b | 255 -> 0 | 1b |
Second (90° -> 180°) | 255 -> 0 | 1b | 0 -> 255 | 0b |
Third (180° -> 270°) | 0 -> 255 | 0b | 255 -> 0 | 0b |
Fourth (270° -> 360°) | 255 -> 0 | 0b | 0 -> 255 | 1b |
The Indexer outputs together with the nHOME signal allow determination of the motor position within the electrical wave. They can be compared with an encoder output to detect discrepancies in the movement of the motor - such as detecting step loss.