Atmel ATSAML22G16A-AUT, Manual

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register values. When down-counting, the WO[x] is cleared at start or compare match between the
COUNT and ZERO values, and set on compare match between COUNT and CCx register values.
The following equation calculates the exact resolution for a single-slope PWM ( R
PWM_SS
) waveform:
�
PWM_SS
= log(TOP+1)
log(2)
The PWM frequency ( f
PWM_SS
) depends on TOP value and the peripheral clock frequency ( f
GCLK_TCC
),
and can be calculated by the following equation:
�
PWM_SS
=
�
GCLK_TC
N(TOP+1)
Where N represents the prescaler divider used (1, 2, 4, 8, 16, 64, 256, 1024).
Match Pulse-Width Modulation Operation (MPWM)
In MPWM, the output of WO[1] is depending on CC1 as shown in the figure below. On on every overflow/
underflow, a one-TC-clock-cycle negative pulse is put out on WO[0] (not shown in the figure).
Figure 35-6. Match PWM Operation
COUNT
MAX
CC0
Period (T)
" match"
ZERO
CCx= Zero
CC1
CCx=TOP
" clear" update
WO[1]
The table below shows the update counter and overflow event/interrupt generation conditions in different
operation modes.
Table 35-3. Counter Update and Overflow Event/interrupt Conditions in TC
Name Operation TOP Update Output Waveform OVFIF/Event
On Match On Update Up Down
NFRQ Normal Frequency PER TOP/ ZERO Toggle Stable TOP ZERO
MFRQ Match Frequency CC0 TOP/ ZERO Toggle Stable TOP ZERO
NPWM Single-slope PWM PER TOP/ ZERO See description above. TOP ZERO
MPWM Single-slope PWM CC0 TOP/ ZERO Toggle Toggle TOP ZERO
Related Links
PORT: IO Pin Controller on page 538
35.6.2.7. Double Buffering
The Compare Channels (CCx) registers, and the Period (PER) register in 8-bit mode are double buffered.
Each buffer register has a buffer valid bit (CCBUFVx or PERBUFV) in the STATUS register, which
indicates that the buffer register contains a new valid value that can be copied into the corresponding
register. As long as the respective buffer valid status flag (PERBUFV or CCBUFVx) are set to '1', related
syncbusy bits are set (SYNCBUSY.PER or SYNCBUSY.CCx), a write to the respective PER/PERBUF or
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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