12. Timer B
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12.2.4 A/D Trigger Mode
A/D trigger mode is used together with simultaneous sample sweep mode or delayed trigger mode 0 of
A/D conversion to start A/D conversion. It is used in timer B0 and timer B1 only. In this mode, the timer
starts counting by one trigger until the count value becomes 000016. Figure 12.23 shows the TBiMR
register in A/D trigger mode and Figure 12.24 shows the TB2SC register.
Item Specification
Count Source f1, f2, f8, f32, and fC32
Count Operation • Decrement
• When the timer underflows, reload register contents are reloaded before
stopping counting
• When a trigger is generated during the count operation, the count is not
affected
Divide Ratio 1/(n+1) n: Setting value of TBi register (i=0,1)
000016-FFFF16
Count Start Condition When the TBiS (i=0,1) bit in the TABSR register is 1(count started),
TBiEN(i=0,1) in TB2SC register is 1 (A/D trigger mode) and the following
trigger is generated.(Selection based on bits TB2SEL in the TB2SC)
• Timer B2 interrupt
• Underflow of Timer B2 interrupt generation frequency counter setting
Count Stop Condition • After the count value is 000016 and reload register contents are reloaded
• Set the TBiS bit to 0 (count stopped)
I
nterrupt Request Timer underflows
(1)
Generation Timing
TBiIN Pin Function I/O port
Read From Timer Count value can be read by reading TBi register
Write To Timer
(2)
• When writing in the TBi register during count stopped.
Value is written to both reload register and counter
• When writing in the TBi register during count.
Value is written to only reload register (Transfered to counter when reloaded next)
NOTES:
1: A/D conversion is started by the timer underflow. For details refer to 15. A/D Converter.
2: When using in delayed trigger mode 0, set the larger value than the value of the timer B0 register
to the timer B1 register.
Table 12.9 Specifications in A/D Trigger Mode
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