MAX6955：微处理器到LED显示器的高效驱动器

需积分: 10 68 浏览量更新于2024-07-23 收藏 550KB PDF 举报

"MAX6955是一款紧凑型显示器驱动器，通过兼容I2C的两线串行接口连接微处理器与7段、14段和16段LED显示器。它能驱动最多16个7段数码管、8个14段数码管、8个16段数码管或128个独立LED，并能在低至2.7V的电源电压下工作。该驱动器包含了5个I/O扩展器或通用输入/输出(GPIO)线路，其中一些或全部可配置为按键开关读取器。内置开关矩阵扫描和消抖功能，可以处理最多32个开关。芯片上集成了完整的14和16段ASCII字符库、7段显示的十六进制字体、复用扫描电路、阳极和阴极驱动器以及用于存储每个位的静态RAM。最大段电流可以通过一个外部电阻设置，每个数字的亮度可以通过16级内部数字亮度控制独立调整。MAX6955还包括低功耗关断模式、扫描限制寄存器（允许用户显示1到16个数字）、段闪烁同步功能，以及开漏中断输出。" 详细说明: 1. **接口特性**：MAX6955采用I2C兼容的2线串行接口，这使得它能轻松与各种微处理器通信，减少了所需的硬件引脚，降低了系统复杂性。 2. **驱动能力**：这款驱动器支持多种类型的LED显示器组合，包括7段、14段和16段，同时能驱动多达128个独立的LED，非常灵活，适用于各种显示需求。 3. **电源兼容性**：能在2.7V至5.5V的宽电压范围内工作，适应低电压环境，提高了电源设计的灵活性。 4. **GPIO功能**：集成的5个GPIO线路可以配置为读取按键开关的状态，简化了按键系统的实现，同时也可用作额外的I/O扩展。 5. **开关矩阵扫描和消抖**：自动扫描和消抖功能确保了按键输入的稳定性和准确性，避免了由于机械开关抖动导致的误操作。 6. **字符库**：内置了14和16段ASCII字符库以及7段显示的十六进制字体，方便显示各种文本信息，无需额外的字符编码转换。 7. **亮度控制**：16级内部数字亮度控制允许用户根据环境光线和视觉需求独立调整每个显示单元的亮度。 8. **低功耗模式**：在不使用时，MAX6955可以进入低功耗模式，以减少能源消耗。 9. **扫描限制寄存器**：用户可以通过扫描限制寄存器选择要显示的数码管数量，从1到16个，有助于优化系统性能和功耗。 10. **段闪烁功能**：可用于提示或其他视觉效果，使显示屏更具动态感。 11. **开漏中断输出**：提供中断信号，当特定事件发生（如按键按下）时通知微处理器，增强了系统的实时响应能力。 MAX6955是一款功能强大且灵活的LED显示器驱动器，适用于需要高集成度、低功耗和多种显示方式的嵌入式系统设计。

MAX6955

2-Wire Interfaced, 2.7V to 5.5V LED Display

Driver with I/O Expander and Key Scan

_______________________________________________________________________________________ 7

from the MAX6955, and generates the SCL clock that

synchronizes the data transfer (Figure 2).

The MAX6955 SDA line operates as both an input and

an open-drain output. A pullup resistor, typically 4.7kΩ,

is required on the SDA. The MAX6955 SCL line oper-

ates only as an input. A pullup resistor, typically 4.7kΩ,

is required on SCL if there are multiple masters on the

2-wire interface, or if the master in a single-master sys-

tem has an open-drain SCL output.

Each transmission consists of a START condition

(Figure 3) sent by a master, followed by the MAX6955

7-bit slave address plus R/W bit (Figure 4), a register

address byte, 1 or more data bytes, and finally a STOP

condition (Figure 3).

Start and Stop Conditions

Both SCL and SDA remain high when the interface is

not busy. A master signals the beginning of a transmis-

sion with a START (S) condition by transitioning SDA

from high to low while SCL is high. When the master

has finished communicating with the slave, it issues a

STOP (P) condition by transitioning the SDA from low to

high while SCL is high. The bus is then free for another

transmission (Figure 3).

Bit Transfer

One data bit is transferred during each clock pulse.

The data on the SDA line must remain stable while SCL

is high (Figure 5).

Acknowledge

The acknowledge bit is a clocked 9th bit that the recipi-

ent uses to handshake receipt of each byte of data

(Figure 6). Thus, each byte transferred effectively

requires 9 bits. The master generates the 9th clock

pulse, and the recipient pulls down SDA during the

acknowledge clock pulse, such that the SDA line is sta-

ble low during the high period of the clock pulse. When

the master is transmitting to the MAX6955, the

MAX6955 generates the acknowledge bit because the

MAX6955 is the recipient. When the MAX6955 is trans-

mitting to the master, the master generates the

acknowledge bit because the master is the recipient.

Slave Address

The MAX6955 has a 7-bit-long slave address (Figure

4). The eighth bit following the 7-bit slave address is the

R/W bit. It is low for a write command, high for a read

command.

The first 3 bits (MSBs) of the MAX6955 slave address

are always 110. Slave address bits A3, A2, A1, and A0

are selected by the address input pins AD1 and AD0.

These two input pins can be connected to GND, V+,

SDA, or SCL. The MAX6955 has 16 possible slave

addresses (Table 5) and therefore a maximum of 16

MAX6955 devices can share the same interface.

DISPLAY TYPE

7 SEGMENT

(16-CHARACTER

HEXADECIMAL FONT)

14 SEGMENT/

16 SEGMENT

(104-CHARACTER ASCII FONT MAP)

DISCRETE LEDs

(DIRECT CONTROL)

Monocolor 16 8 128

Bicolor 8 4 64

Table 1. MAX6955 Drive Capability

1dp

2dp

g1 g2

dp dp

1e 1c

2f 2b

2e 2c

g1 g2

Figure 1. Segment Labeling for 7-Segment Display, 14-Segment Display, and 16-Segment Display

MAX6955

2-Wire Interfaced, 2.7V to 5.5V LED Display

Driver with I/O Expander and Key Scan

8 _______________________________________________________________________________________

Message Format for Writing

A write to the MAX6955 comprises the transmission of

the MAX6955’s slave address with the R/W bit set to

zero, followed by at least 1 byte of information. The first

byte of information is the command byte, which deter-

mines which register of the MAX6955 is to be written by

the next byte, if received. If a STOP condition is detect-

ed after the command byte is received, then the

MAX6955 takes no further action (Figure 7) beyond

storing the command byte.

Any bytes received after the command byte are data

bytes. The first data byte goes into the internal register of

the MAX6955 selected by the command byte (Figure 8).

If multiple data bytes are transmitted before a STOP

condition is detected, these bytes are generally stored

in subsequent MAX6955 internal registers because the

command byte address generally autoincrements

(Table 6) (Figure 9).

DIGIT O0 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17

O18

0 CCO — a1 a2 b c d1 d2 e

g1 g2 h

1 — CC1 a1 a2 b c d1 d2 e

g1 g2 h

2 a1 a2 CC2 — b c d1 d2 e

g1 g2 h

3 a1 a2 — CC3 b c d1 d2 e

g1 g2 h

4 a1 a2 b c CC4 — d1 d2 e

g1 g2 h

5 a1 a2 b c — CC5 d1 d2 e

g1 g2 h

6 a1 a2 b c d1 d2 CC6 — e

g1 g2 h

7 a1 a2 b c d1 d2 — CC7 e

g1 g2 h

DIGIT O0 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18

0 CCO — a — bcd— e f g1 g2 h i j k l m dp

1 — CC1 a — bcd— e f g1 g2 h i j k l m dp

2a— CC2 — bcd— e f g1 g2 h i j k l m dp

3a——CC3 b c d — e f g1 g2 h i j k l m dp

4a— b c CC4 — d — e f g1 g2 h i j k l m dp

5a— bc— CC5 d — e f g1 g2 h i j k l m dp

6a— bcd— CC6 — e f g1 g2 h i j k l m dp

7a— bcd——CC7 e f g1 g2 h i j k l m dp

Table 2. Connection Scheme for Eight 16-Segment Digits

Table 3. Connection Scheme for Eight 14-Segment Digits

DIGIT

O0 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17

O18

0, 0a

CC0 — 1a — 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

1, 1a

— CC1 1a — 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

2, 2a

1a — CC2 — 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

3, 3a

1a ——CC3 1b 1c 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

4, 4a

1a — 1b 1c CC4 — 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

5, 5a

1a — 1b 1c — CC5 1d 1dp 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

6, 6a

1a — 1b 1c 1d 1dp CC6 — 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

7, 7a

1a — 1b 1c 1d 1dp — CC7 1e 1f 1g 2a 2b 2c 2d 2e 2f 2g

2dp

Table 4. Connection Scheme for Sixteen 7-Segment Digits

剩余38页未读，继续阅读

Blueice200800105

粉丝: 0
资源: 1

MAX6955：微处理器到LED显示器的高效驱动器

MAX96705 datasheet

MAX9286 datasheet

max5233 datasheet

MAX4444datasheet

max706 datasheet

MAX6675 datasheet

MAX6 datasheet

max15157 data sheet

MAX1617 datasheet

MAX9286datasheet

最新资源