參數(shù)資料
型號: UPD17231
廠商: NEC Corp.
元件分類: 4位微控制器
英文描述: 4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER
中文描述: 4位單片機的小型通用紅外遙控器
文件頁數(shù): 41/92頁
文件大?。?/td> 378K
代理商: UPD17231
Data Sheet U14360EJ1V0DS00
μ
PD17230, 17231, 17232, 17233, 17234, 17235, 17236
41
5.3
Carrier Generator Circuit for Remote Controller
μ
PD17236 is provided with a carrier generator circuit for the remote controller.
The remote controller carrier generator circuit consists of a 7-bit counter, NRZ high-level timer modulo register
(NRZHTMM), and NRZ low-level timer modulo register (NRZLTMM). The high-level and low-level periods are set
in the corresponding modulo registers through the DBF to determine the carrier duty factor and carrier frequency.
Either the system clock (f
X
) divided by two or the original oscillation can be selected by mask option as an input
to the 7-bit counter (where the clock for generating carrier is Rf
X
). When Rf
X
is oscillated by a 4-MHz oscillator,
therefore, the input clock is 2 MHz (f
X
/2) or 4 MHz (f
X
).
The NRZ high-level output timer modulo register is called NRZHTMM, and the NRZ low-level timer modulo register
is called NRZLTMM. Data is written to these registers by the PUT instruction. The contents for these register are
read by the GET instruction.
Bit 7 of NRZLTMM specifies whether the carrier or high level is output to the REM pin. To output the carrier, be
sure to clear bit 7 to 0.
5.3.1
Remote controller signal output control
The REM pin, which outputs the carrier, is controlled by bits NRZ and NRZBF for the register file and timer 0. While
the NRZ content is “1”, the clock generated by the remote controller carrier generator circuit is output to the REM pin;
while the NRZ content is “0”, the REM pin outputs a low level. The NRZBF content is 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.
If the interrupt signal is generated from timer 0 with the REM pin at the high level, NRZ being “1”, and the carrier
clock at the high level, the REM pin output is not in accordance with the updated content 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).
When the content of NRZ is “0”, the remote controller carrier generator circuit stops. However, if the clock for timer
0 is output from the remote controller carrier generator circuit, the clock continues to operate, even when the NRZ
content becomes “0”.
An actual example showing a remote controller signal output to the REM pin is presented below.
相關PDF資料
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