Fujitsu FR81S User Manual
CHAPTER 19: BASE TIMER
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: BASE TIMER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
50
5.4.2. Operation in Reload Mode
This section explains the operation in reload mode.
This section explains the operation in reload mode.
Overview
In this mode, the value set in the base timer x cycle setting register (BTxPCSR) is reloaded every time an
underflow occurs to ensure that countdown is continued. To use this mode, set reload mode by resetting the
MDSE bit of the base timer x timer control register (BTxTMCR) to "0"(MDSE=0).
Operation
Activation
Activate the 16/32-bit reload timer with the following procedure:
1. Permit 16/32-bit reload timer operation by setting the CTEN bit of the base timer x timer control
register (BTxTMCR) to "1"(CTEN=1).
The 16/32-bit reload timer begins to wait for an activation trigger.
2. Enter an activation trigger by one of the following methods:
⋅
Set the STRG bit of the base timer x timer control register (BTxTMCR) to "1" (software trigger).
⋅
Enter an effective edge (an edge set in the EGS1 and EGS0 bits) for an external activation trigger
(TGIN signal).
Notes:
⋅
The external activation trigger (TGIN signal) entry method varies depending on the I/O mode specified
by the I/O selection register (BTSEL01). See "5.2 I/O Allocation".
⋅
To start counting as soon as the operation is permitted, set both CTEN and STRG bits of the base timer x
timer control register (BTxTMCR) to "1".
Counting Operation
When an activation trigger is input, the value (cycle) set in the base timer x cycle setting register (BTxPCSR)
is loaded to the down counter, which begins counting down, after one of the following lengths of time elapses:
⋅
If a software trigger is input: 1T (T: Count clock cycle)
⋅
If an external activation trigger (TGIN signal) is input: 2T to 3T (T: Count clock cycle)
MB91520 Series
MN705-00010-1v0-E
683