UPD6600A NEC, UPD6600A Datasheet - Page 8

• Manufacturer Part Number: UPD6600A
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER FOR REMOTE CONTROL TRANSMISSION
• Manufacturer: NEC

8
10. TIMER
the 9-bit down counter and the remaining 1 bit serves as the 1-bit latch, which determines the carrier output validity.
down count operation. Down counting stops after all of the 9 bits become 0. When down counting is stopped, the signal
indicating that the timer operation has stopped, is output. If the CPU is at standby (HALT TIMER) for the timer operation
completion, the standby (HALT) condition is released and the next instruction will be executed. If the next instruction
again sets the value of the down counter, down counting continues without any error (the carrier output of the REM pin
is not affected).
the timer is done by the timer manipulation instruction.
or not to output the carrier can be selected by the MSB for the timer register block. Set “1”, when outputting the carrier,
or “0”, when not outputting the carrier.
outputting the carrier, the REM pin output will become low level.
pin is low, when the carrier is being output to the REM pin, or it is high, when the carrier is not being output to the REM
pin.
the oscillation stop mode is initiated after down counting is stopped (after 0).
Cautions 1. Because the timer clock is not synchronized with the carrier output, the pulse width may be
S-OUT
REM
The timer block determines the transmission output pattern. The timer consists of 10 bits, of which 9 bits serve as
The 9-bit down counter is decremented (–1) every 8/f
Set the down count time according to the following calculation; (set value (HEX) + 1)
When the down counter is operating, the remote control transmission carrier can be output to the REM pin. Whether
If all the down counter bits become “0”, when outputting the carrier, the carrier output will be stopped. When not
A signal in synchronization with the REM output is output to the S-OUT pin. However, the waveform for the S-OUT
If the HALT instruction, which initiates the oscillation stop mode, is executed when the down counter is operating,
Timer operation STOP/RUN is controlled by the control register (P
At reset (all clear) time, the REM pin goes low and S-OUT pin goes high. All 10 bits of the timer are cleared to 000H.
From low-voltage
detector (reset)
circuit
2. Reset caused by the low-voltage detector circuit causes the S-OUT pin to output low level.
shortened at the beginning and end of the carrier output.
Figure 10-1. Timer Block Organization
Carrier
(fosc/12, fosc/8)
Selected by control register
MSB
1/0
OSC
Clear
(s) in synchronization with the machine cycle, after starting
Set by timer mainpulation instruction
Zero detection circuit
9-bit down counter
1
). (Refer to 13. CONTROL REGISTER (P
8/f
PD6124A, 6600A
D of control register P
OSC
2
(Timer RUN/STOP)
. Setting the value to
1
1
).)
fosc/8