831
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
Figure 35-20. 2-bit Gray Up/Down Counter.
35.6.16
Write Protection System
In order to bring security to the Timer Counter, a write protection system has been implemented.
The write protection mode prevent the write of TC_BMR, TC_FMR, TC_CMRx, TC_SMMRx,
TC_RAx, TC_RBx, TC_RCx registers. When this mode is enabled and one of the protected reg-
isters write, the register write request canceled.
Due to the nature of the write protection feature, enabling and disabling the write protection
mode requires the use of a security code. Thus when enabling or disabling the write protection
mode the WPKEY field of the TC_WPMR register must be filled with the “TIM” ASCII code (cor-
responding to 0x54494D) otherwise the register write will be canceled.
35.6.17
Fault Mode
At anytime, the TC_RCx registers can be used to perform a comparison on the respective cur-
rent channel counter value (TC_CVx) with the value of TC_RCx register.
The CPCSx flags can be set accordingly and an interrupt can be generated.
This interrupt is processed but requires an unpredictable amount of time to be achieve the
required action.
It is possible to trigger the FAULT output of the TIMER1 with CPCS from TC_SR0 register
and/or CPCS from TC_SR1 register. Each source can be independently enabled/disabled by
means of TC_FMR register.
This can be useful to detect an overflow on speed and/or position when QDEC is processed and
to act immediately by using the FAULT output.
Figure 35-21. Fault Output Generation
TIOAx
TIOBx
DOWNx
TC_RCx
WAVEx = GCENx =1
TC_SR0 flag CPCS
TC_FMR / ENCF0
FAULT (to PWM input)
OR
AND
AND
TC_SR1 flag CPCS
TC_FMR / ENCF1
Summary of Contents for SAM4S Series
Page 44: ...44 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Page 412: ...412 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Page 1105: ...1105 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Page 1143: ...1143 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 4 64 lead LQFP Package Drawing ...
Page 1145: ...1145 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 5 64 lead QFN Package Drawing ...