Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet

SAM4E [DATASHEET]

Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14

980

predefined value is configurable and corresponds to (MAXFILT + 1) * t

peripheral clock

 ns. After being filtered there is

no reason to have two edges closer than (MAXFILT + 1) * t

peripheral clock

 ns under normal mode of operation.

MAXFILT must be tuned according to several factors such as the peripheral clock frequency, type of rotary sensor
and rotation speed to be achieved.

When the POSEN bit is set in the TC_BMR, the motor axis position is processed on channel 0 (by means of the
PHA, PHB edge detections) and the number of motor revolutions are recorded on channel 1 if the IDX signal is
provided on the TIOB1 input. The position measurement can be read in the TC_CV0 register and the rotation
measurement can be read in the TC_CV1 register.

Channel 0 and 1 must be configured in capture mode (WAVE = 0 in TC_CMR0).

In parallel, the number of edges are accumulated on timer/counter channel 0 and can be read on the TC_CV0
register.

Therefore, the accurate position can be read on both TC_CV registers and concatenated to form a 32-bit word.

The timer/counter channel 0 is cleared for each increment of IDX count value.

Depending on the quadrature signals, the direction is decoded and allows to count up or down in timer/counter
channels 0 and 1. The direction status is reported on TC_QISR.

Peripheral Clock

MAXFILT = 2

PHA

PHB

Abnormally formatted optical disk strips (theoretical view)  

PHA

PHB

strip edge inaccurary due to disk etching/printing process 

resulting PHA, PHB electrical waveforms

PHA

PHB

Even with an abnorrmaly formatted disk, there is no occurence of  PHA, PHB switching at the same time.

QERR

duration < MAXFILT