MB89190/190A series
Chapter 13 Remote Controller Transmit Frequency Generator
13-15
13.
6 NotesonUsingRemoteControllerTransmitFrequencyGenerator
Notes on using the remote controller transmit frequency generator are provided
below.
T Notes on using remote controller transmit frequency generator
Switching output pin
The P37/BZ/RCO pin can function as a general-purpose port, buzzer output, and remote controller
transmit frequency output.
The buzzer output has priority over the remote controller transmit
frequency output. So, when using the P37/BZ/RCO pin as the remote controller transmit frequency
output pin, always write 00H to the buzzer register (BZCR) to stop the buzzer output.
Restrictions on H-width setting
When 0.5 tINST is selected as the cycle of the internal count clock, set the value of the H-width setting
bits of remote controller control register 1 (RCR1: HSC5 to HSC0) from 00H to 3EH.
When 1/8/32 tINST is selected as the internal count clock cycle, set the value of the H-width setting bits
of remote controller control register 1 (RCR1: HSC5 to HSC0) from 01H to 3EH.
When 00H is set, the H level for 0.5 tINST is output from the RCO pin.
In both cases (when 0.5 tINST or 1/8/32 tINST is selected), set a value that is smaller than the cycle
setting bits of remote controller control register 2 (RCR2: SCL5 to SCL0). When a value equal to or
greater than these bits is set, the output of the RCO pin is always held at H level.
Resolution
When 0.5 tINST is selected as the internal count clock cycle, the maximum resolution of the H-width is
1/64 of the cycle (when cycle setting is 3FH). However, when the cycle setting is made smaller, a
minimum resolution of 1/2 of the cycle can be attained for the H-width (when the cycle setting is 01H).
When 1/8/32 tINST is selected as the cycle of the internal count clock, the maximum resolution of the H-
width is 1/63 of the cycle (when the cycle setting is 3FH). However, when the cycle setting is made
smaller, a minimum resolution of 1/2 of the cycle can be attained for the H-width (when the cycle
setting is 02H).
Changing setting of currently operating counter
The 6-bit counter for generating the remote controller transmit frequency is compared directly to the H-
width setting bits (RCR1: HSC5 to HSC0) and the cycle setting bits (RCR2: SCL5 to SCL0).
Consequently, if the setting is made smaller while the counter is operating, an overflow occurs at the
counter and this may lengthen the cycle until a match is detected again; the H-width may also be
made lengthened until a match is detected in the next cycle.
Figure 13.6a shows the setting change made during operation of the remote controller transmit
frequency generator.