ATA6844-DK Atmel, ATA6844-DK Datasheet - Page 23

• Manufacturer Part Number: ATA6844-DK
• Description: Power Management IC Development Tools BLDC Motor Drvr Brd
• Manufacturer: Atmel
• Type: Motor / Motion Controllers & Driversr

Specifications of ATA6844-DK

• Rohs: yes
• Product: Development Kits
• Tool Is For Evaluation Of: ATA6844, ATmega32M1, ATmega32U2
• Input Voltage: 3.3 V, 5 V, 12 V
• Description/function: Atmel ATA6844-DK BLDC Motor Control Kit
• Interface Type: LIN, UART, USB
• Factory Pack Quantity: 1

9.4.1
9.4.2
9.4.3
9.4.4
9236A–AUTO–08/11
MC_UNLOCKED
MC_RAMPUP (Not Yet Implemented/Activated)
MC_PRELOCKED1
MC_PRELOCKED2
Note:
Note:
• No control is possible because there is no back EMF feedback for commutation control. No
• PWM duty-cycle and the commutation delay time are predefined software parameters.
• The motor starts with a fixed PWM signal and a constrained commutation cycle.
• The ADC runs in parallel and measures at four different points between the commutation
• >debug mode< - the state machine stays in this mode as long as the user switches
• >normal mode< - the state machine switches automatically into the next MC_PRELOCKED
• This state is intended to implement code for BLDC motor acceleration until sufficient back
• The MC_RAMPUP mode improves the startup behavior in case of PWM duty-cycle and the
• The interrupt service routines (ISR) for falling and rising edges of the internal analog
• The state machine switches automatically into the next MC_PRELOCKED mode
• The AC falling and rising edges are time stamped and stored in a buffer (AC data pipeline).
• The state machine switches automatically into the next MC_PRELOCKED mode as soon
PI controller is running for PWM duty-cycle control.
steps.
manually into another mode (command control via UART interface).
mode after a pre-programmed time.
EMF signal can be detected. In the implemented software, only a single set of PWM and
duty cycle values is active. The single set is sufficient to start the enclosed motor.
corresponding commutation time for a reliable back EMF feedback is not known. This mode
provides more stable startup especially for parameters of unknown BLDC motors or
varying loads.
comparators (AC) and the back EMF feedback are enabled. The commutation is not yet
controlled based on these measured parameters.
The averages of the time stamps are calculated.
as the calculated average of one electrical rotation is identical (about ±30%) to six times
the constrained commutation time.
Enabled AC ISRs in UNLOCKED mode can disturb the startup phase, because it is very impor-
tant for the PI controller to get certain back EMF data from the AC data pipeline. Acquiring
useful back EMF data is only possible with a motor running so that sufficient back EMF voltage
is generated.
The comparison is an indicator for reliability of the AC data pipeline. The faster the rotation, the
better matches result for this comparison.
Atmel ATA6843/ATA6844
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