MB89190/190A series
Chapter 13 Remote Controller Transmit Frequency Generator
13-3
13.
1 OverviewofRemoteControllerTransmitFrequencyGenerator
The remote controller transmit frequency generator is a 6-bit binary counter that
can select one internal count clock from four different clocks, and can set the
cycle and H-width of the output waveform. As a result, the generator can also be
used as a 6-bit PPG. The output also serves as the buzzer output pin.
T Remote controller transmit frequency generation function
The frequency used by the remote controller is generated and output to the RCO pin.
The cycle and H-width of the output waveform can be set independently.
The count clock can be selected from four different internal clocks.
A frequency of cycle 2 to 26 times the count clock can be generated.
The output also serves as the buzzer output, and the buzzer output has priority over the remote
controller transmit frequency output.
Table 13-1a shows the range in which the output cycle and the H-width of the output can be changed.
Table 13-1a Range of Output Cycle and H-width
Cycle of internal count clock
Cycle of output
H-width of output
0.5 tINST
1 tINST to 32 tINST
0.5 tINST to 31.5 tINST
1 tINST
2 tINST to 63 tINST
1 tINST to 62 tINST
8 tINST
16 tINST to 504 tINST
8 tINST to 496 tINST
32 tINST
64 tINST to 2016 tINST
32 tINST to 1984 tINST
tINST: Instruction cycle (affected by clock mode, etc.)
The expression that is used when 0.5 tINST is selected as the cycle of the internal count clock is different
from the expression when something other than 0.5 tINST is selected. A calculation example is given for
each of the two cases.
Remark:
A calculation example of the cycle and H-width that can be set using the remote controller
transmit frequency generation function is given below (0.5 tINST selected as cycle of internal
count clock).
When the original oscillation (Fc) is 4.2 MHz and the cycle of the count clock is 0.5 tINST, and
when the compare value for the cycle is 011110B (30-clock cycle) and the compare value for
H-width is 001010B (10-clock width), the H-width and the cycle of the output waveform are
calculated as follows:
Cycle
= (compare value for cycle + 1)
× 0.5 t
INST
= 011110B (30 + 1-clock cycle)
× 0.5 × 4 / Fc
= 31
× 0.475 s
= 14.725 s
H-width = (compare value for H-width + 1)
× 0.5 t
INST
= 001010B (width of 10 + 1 clocks)
× 0.5 × 4/Fc
= 11
× 0.475 s
= 5.225 s
When the setting of the H-width is equal to or greater than the setting of the cycle, the H level
is output.