UPD64 datasheet(21/68 Pages) NEC

21 / 68 page

µPD63, 63A, 64

4.3 Carrier Output

The carrier for remote-controlled transmission can be output from the REM pin by clearing (to 0) bit 2 of the control

As shown in Figure 4-3, in the case where the timer stops when the carrier is at a high level, the carrier continues

to be output until its next fall and then stops due to the function of the carrier synchronous circuit. When the timer

starts operation, however, the high-level width of the first carrier may become shorter than the specified width.

Figure 4-3. Timer Output (when carrier is output)

Timer value: (Set value+1)

× 64/fX (or 128/fX)

LED

REM (at low-level start)

REM (at high-level start)

Note 1

Note 2

Notes 1. Error when the REM output ends: Lead by “the carrier’s low-level width” to lag by “the carrier’s high-

level width”

2. Error of the carrier’s high-level width: 0 to “the carrier’s high-level width”

4.4 Software Control of Timer Output

The timer output can be controlled by software. As shown in Figure 4-4, the pulse with a minimum width of 1-

instruction cycle (64/fX) can be output.

Figure 4-4. Pulse Output of 1-Instruction Cycle Width

MOV T, #0000000000B; low-level output from the REM pin

MOV T, #1000000000B; high-level output from the REM pin

MOV T, #0000000000B; low-level output from the REM pin

64/fX

LED

REM

UPD64 Datasheet(PDF) 21 Page - NEC