Datasheet
The current value of the counter is accessible in real time by reading the Counter Value register (TC_CV). The
counter can be reset by a trigger
. In this case, the counter value passes to zero on the next valid edge of the selected
clock.
50.6.3 Clock Selection
At block level, input clock signals of each channel can be connected either to the external inputs TCLKx, or to the
internal I/O signals TIOAx for chaining
(1)
by programming the Block Mode register (TC_BMR). See Clock Chaining
Selection.
Each channel can independently select an internal or external clock source for its counter
(2)
:
• External clock signals: XC0, XC1 or XC2
• Internal clock signals: PCK6 or PCK7 (TC0 only), MCK/8, MCK/32, MCK/128, SLCK
This selection is made by the TCCLKS bits in the Channel Mode register (TC_CMRx).
The selected clock can be inverted with TC_CMRx.CLKI. This allows counting on the opposite edges of the clock.
The burst function allows the clock to be validated when an external signal is high. The BURST parameter in the
TC_CMRx defines this signal (none, XC0, XC1, XC2). See Clock Selection.
Note:
1. In Waveform mode, to chain two timers, it is mandatory to initialize some parameters:
– Configure TIOx outputs to 1 or 0 by writing the required value to TC_CMRx.ASWTRG.
– Bit TC_BCR.SYNC must be written to 1 to start the channels at the same time.
2. In all cases, if an external clock or asynchronous internal clock PCK6 or PCK7 (TC0 only) is used, the duration
of each of its levels must be longer than the peripheral clock period, so the clock frequency will be at least 2.5
times lower than the peripheral clock.
Figure 50-2. Clock Chaining Selection
Timer Counter
Channel 0
SYNC
TC0XC0S
TIOA0
TIOB
0
XC0
XC1 = TCLK1
XC2 = TCLK2
TCLK0
TIOA1
TIOA2
Timer Counter
Channel 1
SYNC
TC1XC1S
TI
OA1
TIOB1
XC0 = TCLK0
XC1
XC2 = TCLK2
TCLK1
TIOA0
TIOA2
Timer Counter
Channel 2
SYNC
TC2XC2S
TIOA
2
TIOB2
XC0 = TCLK0
XC1 = TCLK1
XC2
TCLK2
TIOA0
TIOA1
SAM E70/S70/V70/V71 Family
T
imer Counter (TC)
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 1494