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PDF NT6868C Data sheet ( Hoja de datos )
| Número de pieza | NT6868C | |
| Descripción | Keyboard Controller | |
| Fabricantes | Novatek | |
| Logotipo |  |
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NT6868C
Keyboard Controller
Features
n Built-in 6502 8-bit CPU
n 2 MHz CPU operation frequency
n 4K bytes of ROM
n 128 bytes of SRAM
n One 8-bit programmable base timer with 1 - 256 µsec
interval
n 29 programmable bi-directional I/O pins
n 3 LED direct sink pins with internal serial resistors
n Mask optional for built-in RC oscillator with an
external resistor or external ceramic resonator
applied
n Mask optional for DATA/CLK driving capability
n Watch-dog timer
n Built-in power-on reset
n Built-in low voltage reset
n CMOS technology for low power consumption
n Available in 40 pin DIP package and 40 pad CHIP
FORM
General Description
NT6868C is a single chip micro-controller for keyboard
applications. It incorporates a 6502 8-bit CPU core, 4K
bytes of ROM and 128 bytes of RAM used as working
RAM and stack area. It also includes 29 programmable
bi-directional I/O pins and one 8-bit pre-loadable base
timer.
Additionally, it includes a built-in low voltage reset, a
4MHz RC oscillator that only requires an externally
applied or a 4MHz ceramic resonator, and a watch-dog
timer that has a resistor preventing system standstill.
Pin Configuration
GND
NC
DATA
CLK
P30
P31
P32
P33
P34
RESET
P00
P01
P02
P03
P04
P05
P06
P07
P10
P11
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40 OSCI
39 R/OSCO
38 VDD
37 LED2
36 LED1
35 LED0
34 P27
33 P26
32 P25
31 P24
30 P23
29 P22
28 P21
27 P20
26 P17
25 P16
24 P15
23 P14
22 P13
21 P12
Pad Configuration
P PP PP PP PP P
11 11 11 11 00
76 54 32 10 76
26 25 24 23 22 21 20 19 18 17
16 P05
15 P04
P20 27
14 P03
P21 28
13 P02
P22 29
12 P01
P23 30
P24 31
NT6868CH
11 P00
10 RESET
P25 32
9 P34
P26 33
8 P33
P27 34
7 P32
LED0
LED1
35
36
37 38 39 40 1
23 45
6 P31
L VR OG
ED
/
SN
D D O CD
2 SI
C
O
N DC P
CAL3
TK 0
A
1 V2.0
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Timing Generation
This block generates the system timing and control
signal supplied to the CPU and on-chip peripherals.
There are two types of system clock sources: a built-in
RC oscillator or an external ceramic resonator. Both of
them are mask optional and generate a 4MHz system
clock. They also generate 2MHz for the CPU, and 1 MHz
for the base timer. The following shows the relationship
of code type number with oscillation type.
Oscillator
RC OSC
External Resistor
Code Number
1, 5
3, 7
NT6868C
The following table provides the relationship between
the external resistor and the RC OSC frequency. (This is
for reference only)
External Resistor (KΩ )
39
43
47
56
RC OSC Frequency (MHz)
4.7
4.44
4
3.68
Base Timer
The base timer is an 8-bit counter with a 1MHz clock source. The base timer can be enabled/disabled by the CPU. After a
reset, the base timer is disabled and cleared. The base timer can be preset by writing BT7 - BT0 to the BT register at any
time. When enabled, the base timer starts counting from the preset value. When the value reaches FFH, it generates a
timer interrupt only if the timer interrupt is enabled. When it reaches the maximum value of FFH, the base timer will wrap
around and begin counting at 00H. The timer interval can be programmed from 1 - 256 µsec. The base timer can be
enabled by writing a '0' to ' ENBT ' in the TCON (Timer Control) register. The ENBT is a level trigger.
Base timer structure:
1µs
8-Bit timer
BT7 BT6 BT5 BT4 BT2 BT2 BT1 BT0
TMRINT
BT Pre-loaded Data:
Addr.
Bit
7
6
5
4
3
2
1
0 R/W
$00C0 BT BT7 BT6 BT5 BT4 BT3 BT2 BT1 BT0 (W)
Timer Control Register:
$00C1 TCON
-
-
-
-
-
-
- ENBT (W)
INT. Controller
When a BASE TIMER overflow occurs, it will set the IRQTMR flag. The IRQTMR flag cannot be directly accessed by the
software. Once set by an interrupt source, it remains HIGH unless cleared by writing '1' to the corresponding bit in
CLRIRQX ($00C2H). This register is cleared to '0' on initialization by a system reset.
When an interrupt occurs, the CPU will jump to $FFFEH & $FFFFH to execute the interrupt service routine. When a BASE
TIMER interrupt occurs and enters the interrupt service routine, the IRQTMR flag must be cleared by the software.
Interrupt Control Register:
Addr.
$00C2
Bit 7 6 5 4 3 2 1
0 R/W
CLRIRQX
-
-
-
-
-
-
- CLRIRQTMR (W)
5
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Application Circuit For Windows 2000 Standard Code
NT6868C
47K
S0 P15 R_OSC
S1 P30
Scroll Lock
S2 P31 LED 0
S3 P00
.1uF
S4 P01
Num Lock
S5 P02
LED 1
S6 P03
S7 P04
Caps Lock
S8 P13
LED 2
S9 P14
S10 P12
S11 P10
S12 P07
S13 P06
S14
NT6868A/C
P05
VDD
VDD
S15 P11
S16 P16
10uF
S17 P17
S18 P32 GND
GND
R0 P20
R1 P21
DATA
R2 P22
DATA
R3 P23
R4 P24
CLOCK
R5 P25
CLOCK
R6 P26
R7
P27
RESET
10
0.1uF
11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet NT6868C.PDF ] | |
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