68HC05K0 查看數據表（PDF） - Motorola => Freescale
零件编号
产品描述 (功能)
生产厂家
68HC05K0 Datasheet PDF : 12 Pages
| |||
A complete transmission command consists of
several messages. Each command begins with a
start message of nine 1’s followed by the message
appropriate to the key pressed. This message is
repeatedly transmitted until the key is released.
The transmission is terminated after the key is
released by a end message of nine 1’s.
Every message consists of a pre-bit, a pre-bit
pause, a start bit and nine data bits. The pre-bit and
the start-bit are always logical ‘1’. The pre-bit allows
for the set up of the automatic gain control in the
receiving preamplifier. Figure 3 gives the exact
timing relationships for the transmissions.
The command timing in Figure 3 shows that after the
start transmission the message is continually
re-transmitted at intervals of 131ms (approximately
8Hz) until the key is released. This is shown as time
(c). The control timing shows the nine bit instruction
111001110 being transmitted starting with the LSB.
The pre-bit pause is equal to two bit periods and is
followed by a start-bit of logical ‘1’. The pulse train is
continuous during the transition between
transmitting a logic ‘0’ and a logic ‘1’. The modulating
pulse train has a frequency of approximately 32kHz
with a mark-to-space ratio of one to three.
The signal for transmission is output through one port
pin and is used to drive an IR diode amplifier circuit.
(a)
(c)
(c)
(b)
(b)
COMMAND TIMING
START TRANSMISSION
(1)
(d)
(f)
MESSAGE TIMING
(1) (0) (1) (1) (1) (0) (0) (1) (1) (1)
(d)
(d)
(e) (e)
MODULATION
(g) (g)
(h)
Command timing
Message timing
Modulation
(i)
(a) = 32.8ms
(b) = 13.3ms
(c) = 131ms
(d) = 512µs
(e) = 1.024ms
(f) = 3.072ms
(g) = 8µs
(h) = 32µs
(i) = 512µs
start transmission
start command
control transmission
(half-bit time)
(bit time)
(pre-pulse time)
(1/fcarrier)
(half-bit time)
Figure 3 Circuit timing
AN463/D
13 * bit time
16/fcarrier
16/fcarrier
MOTOROLA
3
Share Link: 