HT6221/HT6222

Rev. 1.50

5

October 1, 2007

Functional Description

Keyboard Scan

The HT6221/HT6222 remain in the halt mode during the

standby state (at this time, the oscillator stops, and the

standby current<1

mA). The HT6221 consists of 32 ac-

tive keys, and the HT6222 has 64 active keys. The key-

board forms of the HT6221/ HT6222 are shown below.

When one of the keys (32 or 64 keys) is triggered for over

36ms, the oscillator is enabled and the chip is activated. If

the key is pressed and held for 108ms or less, the 108ms

transmission codes are enabled and comprised of a

header code (9ms), an off code (4.5ms), low byte address

codes (9ms~18ms), high byte address codes

(9ms~18ms), 8-bit data codes (9ms~18ms), and the in-

verse codes of the 8-bit data codes (18ms~9ms). After the

pressed key is held for 108ms, if the key is still held down,

the transmission codes turn out to be a composition of

header (9ms) and off codes (2.5ms) only.

To avoid mistakes made by keyboard scanning or simul-

taneous two-key inputs (except for the three double-key

active functions (K21+K22, K21+K23, and K21+K24),

the HT6221/HT6222 are facilitated with 36ms starting

time.

The HT6221/HT6222 also provide three double-key ac-

tive functions (K21+K22, K21+K23, and K21+K24) for

tape deck recording operations. The double-key opera-

tion rules are shown in timing 4 and timing 6.

Transmission Codes

The transmission codes of the HT6221/HT6222 consist

of a 9ms header code, a 4.5ms off code, 16-bit address

codes (18ms~36ms), 9ms~18ms 8-bit data codes, and

the inverse code of the 8-bit data codes. The following is

an illustration of the transmission codes:

C 1

R 1

R 2

R 3

R 4

R 5

R 6

R 7

R 8

K 1

K 2

K 3

K 4

K 3 3

K 3 4

K 3 5

K 3 6

K 5

K 6

K 7

K 8

K 3 7

K 3 8

K 3 9

K 4 0

K 9

K 1 0

K 1 1

K 1 2

K 4 1

K 4 2

K 4 3

K 4 4

K 1 3

K 1 4

K 1 5

K 1 6

K 4 5

K 4 6

K 4 7

K 4 8

K 1 7

K 1 8

K 1 9

K 2 0

K 4 9

K 5 0

K 5 1

K 5 2

K 2 1

K 2 2

K 2 3

K 2 4

K 5 3

K 5 4

K 5 5

K 5 6

K 2 9

K 3 0

K 3 1

K 3 2

K 6 1

K 6 2

K 6 3

K 6 4

K 2 5

K 2 6

K 2 7

K 2 8

K 5 7

K 5 8

K 5 9

K 6 0

C 2

C 3

C 4

C 5

C 6

C 7

C 8

K 1

K 2

K 3

K 4

K 5

K 6

K 7

K 8

K 9

K 1 0

K 1 1

K 1 2

K 1 3

K 1 4

K 1 5

K 1 6

C 1

C 2

C 3

C 4

R 1

R 2

R 3

R 4

K 1 7

K 1 8

K 1 9

K 2 0

K 2 1

K 2 2

K 2 3

K 2 4

K 2 5

K 2 6

K 2 7

K 2 8

K 2 9

K 3 0

K 3 1

K 3 2

C 5

C 6

C 7

C 8

D O U T

X 2

K e y - i n

( K 1 ~ K 6 4 )

3 6 m s m i n .

9 m s

4 5 m s ~ 6 3 m s

1 0 8 m s

1 0 8 m s

( A 0 ~ A 1 5 + D 0 ~ D 7 + D 0 ~ D 7 )

3 8 k H z ,

3 3 % d u t y c a r r i e r

9 m s

2 . 5 m s

2 . 5 m s

9 m s

K e y E n a b l e s

F o s c = 4 5 5 k H z

4 . 5 m s

0 . 5 6 m s

0 . 5 6 m s

Output format for the DOUT

C a r r i e r

2 6 . 3 m s

8 . 7 7 m s

3 8 k H z

38kHz carrier

The output code carrier of the DOUT pin is shown in Timing 2: