Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet

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SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

An external event can be programmed to be detected on one of the clock sources (XC0, XC1, XC2) or TIOB. The 

external event selected can then be used as a trigger. 
The EEVT parameter in TC_CMR selects the external trigger. The EEVTEDG parameter defines the trigger edge 

for each of the possible external triggers (rising, falling or both). If EEVTEDG is cleared (none), no external event 

is defined.
If TIOB is defined as an external event signal (EEVT = 0), TIOB is no longer used as an output and the compare 

register B is not used to generate waveforms and subsequently no IRQs. In this case the TC channel can only 

generate a waveform on TIOA.
When an external event is defined, it can be used as a trigger by setting bit ENETRG in the TC_CMR.
As in Capture Mode, the SYNC signal and the software trigger are also available as triggers. RC Compare can 

also be used as a trigger depending on the parameter WAVSEL.

The output controller defines the output level changes on TIOA and TIOB following an event. TIOB control is used 

only if TIOB is defined as output (not as an external event).
The following events control TIOA and TIOB: software trigger, external event and RC compare. RA compare 

controls TIOA and RB compare controls TIOB. Each of these events can be programmed to set, clear or toggle the 

output as defined in the corresponding parameter in TC_CMR.

The quadrature decoder logic is driven by TIOA0, TIOB0, TIOB1 input pins and drives the timer/counter of channel 

0 and 1. Channel 2 can be used as a time base in case of speed measurement requirements (refer to 

When writing a 0 to bit QDEN of the TC_BMR, the quadrature decoder logic is totally transparent.
TIOA0 and TIOB0 are to be driven by the two dedicated quadrature signals from a rotary sensor mounted on the 

shaft of the off-chip motor.
A third signal from the rotary sensor can be processed through pin TIOB1 and is typically dedicated to be driven by 

an index signal if it is provided by the sensor. This signal is not required to decode the quadrature signals PHA, 

PHB.
Field TCCLKS of TC_CMRx must be configured to select XC0 input (i.e., 0x101). Field TC0XC0S has no effect as 

soon as quadrature decoder is enabled.
Either speed or position/revolution can be measured. Position channel 0 accumulates the edges of PHA, PHB 

input signals giving a high accuracy on motor position whereas channel 1 accumulates the index pulses of the 

sensor, therefore the number of rotations. Concatenation of both values provides a high level of precision on 

motion system position.
In speed mode, position cannot be measured but revolution can be measured.
Inputs from the rotary sensor can be filtered prior to down-stream processing. Accommodation of input polarity, 

phase definition and other factors are configurable.
Interruptions can be generated on different events.
A compare function (using TC_RC) is available on channel 0 (speed/position) or channel 1 (rotation) and can 

generate an interrupt by means of the CPCS flag in the TC_SRx.