HT6230 Holtek Semiconductor Inc., HT6230 Datasheet - Page 6

• Manufacturer Part Number: HT6230
• Description: Ht6230 -- Infrared Remote Encoder
• Manufacturer: Holtek Semiconductor Inc.

·
Control bit
A control bit is added after two start bits and
will be complemented if one key is released. The
decoder can decide whether the next code is a
new command or not.
Oscillator
The embedded part of the oscillator is an
RC-oscillation circuit. The OSC pin is the input
terminal of the RC-oscillation circuit and is con-
nected to an external ceramic resonator (429kHz).
A resistor of 6.8kW must be in series with the
resonator. The resonator and resistor are
grounded at one side.
Reset (after key release)
In a complete code repetition time, as shown in
the figure below, the following situation of key
release results in a reset action.
logic 1. If the sense input comes from XIN, the
corresponding command code together with
the system code stored in the system latches
are generated.
Two-key system mode
The device goes into this mode by switching
the MS input pin to high state. The pull-high
resistors are only connected to XIN inputs ex-
cept the first scan cycle. In the first scan cycle,
there only exists pull-high resistors in ZIN in-
puts. In this mode, the legal key operation is
that exactly one XIN and one ZIN are con-
nected to two DRS drivers. In the first scan
duration, it detects which key in Z-key matrix
is pressed and generates an enable signal to
latch the system latches. While in the second
scan duration, it detects which key in the
X-key matrix is pressed and generates an en-
abled signal to latch the command latches. Af-
ter being latched, the system and command
codes are transmitted.
6
·
·
Test pins (TT1 and TT2)
There are four modes by the combination of TT1
and TT2.
TT1
During Tsep and debounce time, the device
will reset immediately if a key is released.
During Scan cycle in Tcode, a reset will occur
if a key is released in three cases described be-
low:
¨
¨
¨
0
1
1
0
When one of the key scan drivers is in the
low state
Before that key has been detected
When MS is high and there is no wired con-
nection in Z-key matrix
TT2
0
1
0
1
Normal mode
Reset
Test mode 1
Test mode 2
Mode
April 19, 2000
HT6230