upd17240 Renesas Electronics Corporation., upd17240 Datasheet - Page 52

• Manufacturer Part Number: upd17240
• Description: 4-bit Single-chip Microcontrollers For Small General-purpose Infrared Remote Control Transmitters
• Manufacturer: Renesas Electronics Corporation.

5.3.1
the NRZ contents are “1”, the clock generated by the remote controller carrier generator is output to the REM pin;
while the NRZ contents are “0”, the REM pin outputs a low level. The NRZBF contents are automatically transferred
to NRZ by the interrupt signal generated by timer 0. If data is set in NRZBF in advance, the REM pin status changes
in synchronization with the timer 0 counting operation.
clock at the high level, the REM pin output does not accord with the updated contents of NRZ until the carrier clock
goes low. This processing is useful for holding the high level pulse width from the output carrier constant (refer to
the figure below).
0 is output from the remote controller carrier generator, the clock continues to operate, even when the NRZ contents
become “0”.
52
The REM pin, which outputs the carrier, is controlled by bits NRZ and NRZBF of the register file and timer 0. While
If the interrupt signal is generated from timer 0 with the REM pin at the high level (i.e. NRZ is “1”) and the carrier
When the contents of NRZ are “0”, the remote controller carrier generator stops. However, if the clock for timer
An actual example showing a remote controller signal output to the REM pin is given below.
When REMEN (address 12H, bit 1) of register file is 0 (carrier output)
Note
Remote controller signal output control
Value when (TMCK1, TMCK0) ≠ (1, 1).
When (TMCK1, TMCK0) = (1, 1), the value differs depending on how NRZ is manipulated. If NRZ is set
by an instruction, the width of the first high-level pulse may be shortened. If NRZ is set by data transferred
from NRZBF, the high-level pulse is delayed by the low-level pulse of the carrier clock.
REM
NRZ
MAX. 500 ns (delay)
(f
X
µ PD17240, 17241, 17242, 17243, 17244, 17245, 17246
= 4 MHz, Rf
X
Data Sheet U15002EJ1V1DS
= f
X
Note
/2)
REM pin does not go low
until carrier goes low
even if NRZ becomes 0