281
Reset-Synchronized PWM Mode: The BR value is transferred to GR upon a GRA3 compare
match.
Procedure for Selecting Buffer Mode (Figure 10.47):
1. Set TIOR to select the output compare or input capture function of GR.
2. Set bits BFA3, BFB3 and BFB4 in TFCR to select buffer mode for GR.
3. Set the STR bit in TSTR to 1 to start the TCNT count.
(1)
(2)
(3)
Select general register function
Buffer mode
Select buffer mode
Start counting
Buffer mode
Figure 10.47 Procedure for Selecting Buffer Mode
Buffer Mode Operation: Figure 10.48 shows an example of an operation in buffer mode with
GRA set as an output compare register and GRA and buffer register A (BRA) set for buffer
operation. TCNT operates as a periodic counter that is cleared by a GRB compare match. TIOCA
and TIOCB are set to toggle at compare matches A and B. Since buffer mode is selected, when
TIOCA toggles at compare match A, the BRA value is simultaneously transferred to GRA. This
operation is repeated at every compare match A. The transfer timing is shown in figure 10.49.
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