全面了解红外遥控.doc

全面了解红外遥控 全面了解红外遥控
作者： San Bergmans 作者：圣Bergmans
转载时间： 转载时间：

IR Remote Control Theory 红外遥控控制理论
The cheapest way to remotely control a device within a visible range is via Infra-Red light. 最便宜的方法来远程控制在可见光范围内的设备是通过红外光。 Almost all audio and video equipment can be controlled this way nowadays. 几乎所有的音频和视频设备可以控制这种方式现在。 Due to this wide spread use the required components are quite cheap. 由于这种广泛推广使用所需的组件也相当便宜。 Thus making it ideal for us hobbyists to use for our own projects. 从而使我们理想的爱好者使用我们自己的项目。
This part of my knowledge base will explain the theory of operation of IR remote control, and some of the protocols that are in use in consumer electronics. 这是我的知识基础部分将解释红外遥控操作的理论，一些协议 ， 在消费电子产品中使用。
Infra-Red Light 红外光
Infra-Red actually is normal light with a particular colour. 红外线光 ， 其实是正常的与特定的颜色。 Us humans can't see this colour because it's wave length of 950nm is below the visible spectrum. 我们人类无法看到这个颜色 ， 因为它的波长950nm以下的可见光光谱。 That's one of the reasons why IR is chosen for remote control purposes, we want to use it but we're not interested in seeing it. Another reason is because IR LEDs are quite easy to make, and therefor can be very cheap. 这就是为什么IR是远程控制的目的选择的原因之一，我们要使用它 ， 但我们还没有看到也感兴趣。另一个原因是因为红外灯是相当容易做，并为此可以很便宜。
Although we humans can't see the Infra-Red light emitted from a remote control doesn't mean we can't make it visible. 虽然我们人类无法看到的红外光从远程控制排放并不意味着我们不能使其可见。
A video camera or digital camera can "see" the Infra-Red light as you can see in this picture. 一台摄像机或数码相机可以“看到”的红外光 ， 你可以看到在这张图片。
Unfortunately for us there are many more sources of Infra-Red light. The sun is the brightest source of all, but there are many others, like: light bulbs, candles, central heating system, and even our body radiates Infra-Red light. 不幸的是 ， 我们还有更多的来源红外光。太阳是所有聪明的源泉，但也有许多人，如：灯泡，蜡烛，中央供暖系统，甚至我们的身上散发红外线光。 In fact everything that radiates heat, also radiates Infra-Red light. 事实上 ， 一切辐射热，还辐射红外光。
Therefor we have to take some precautions to guarantee that our IR message gets across to the receiver without errors. 为此 ， 我们必须采取一些预防措施 ， 以保证我们的红外信息传递给接收方得到不出现错误。
Modulation 调制
Modulation is the answer to make our signal stand out above the noise. With modulation we make the IR light source blink in a particular frequency. 调制答案是 ， 使我们的上述立场的信号噪音。随着调制我们有必要在某个特定的频率的红外光源闪烁。 The IR receiver will be tuned to that frequency, so it can ignore everything else. 的红外接收器将被调整到该频率，因此可以忽略一切。
You can think of this blinking as attracting the receiver's attention. 你可以认为这是为吸引闪烁接收机的注意。 We humans also notice the blinking of yellow lights at construction sites instantly, even in brought daylight. 我们也注意到了人类的黄色灯光闪烁在建筑地盘，也可立即在带来阳光。

In the picture above you can see a modulated signal driving the IR LED of the transmitter on the left side. 在上面的图片你可以看到一个调制信号驱动红外发光二极管的左侧发射机。 The detected signal is coming out of the receiver at the other side. 检测到的信号的接收器来进行的另一边。
In serial communication we usually speak of 'marks' and 'spaces'. 在串行通信 ， 我们通常说的'商标'和'空间'。 The 'space' is the default signal, which is the off state in the transmitter case. 在'太空'就是预设的信号，这是在关闭状态下发射。 No light is emitted during the 'space' state. 没有灯光释放出的'太空'的状态。 During the 'mark' state of the signal the IR light is pulsed on and off at a particular frequency. 在'商标'的红外光脉冲在某个特定的频率和关闭信号状态。 Frequencies between 30kHz and 60kHz are commonly used in consumer electronics. 60kHz至30kHz的频率与通常用于消费电子产品。
At the receiver side a 'space' is represented by a high level of the receiver's output. 在接收端一'空间'是由一个接收器的输出高层次的代表。 A 'mark' is then automatically represented by a low level. 甲'标志'，然后自动低层次的代表。
Please note that the 'marks' and 'spaces' are not the 1-s and 0-s we want to transmit. 请注意，'商标'和'空间'不是1 - s和0 - S我们要传送。 The real relationship between the 'marks' and 'spaces' and the 1-s and 0-s depends on the protocol that's being used. 之间的'商标'和'空间'和真正的关系1 - s和0 - š取决于 ， 目前已被使用的协议。 More information about that can be found on the pages that describe the protocols. 更多信息可在网页上找到描述该议定书。
The Transmitter 发射器
The transmitter usually is a battery powered handset. 发射器通常是手机电池供电。 It should consume as little power as possible, and the IR signal should also be as strong as possible to achieve an acceptable control distance. 它应消耗尽可能少的权力，红外信号也应尽可能地达成可接受的控制距离强劲。 Preferably it should be shock proof as well. 最好应该防震以及。
Many chips are designed to be used as IR transmitters. 许多芯片被设计为红外发射器使用。 The older chips were dedicated to only one of the many protocols that were invented. Nowadays very low power microcontrollers are used in IR transmitters for the simple reason that they are more flexible in their use. 旧的芯片是专门只认为是发明了许多协议之一。现在非常低功耗微控制器的红外发射器是用于理由很简单 ， 他们在使用上更加灵活。 When no button is pressed they are in a very low power sleep mode, in which hardly any current is consumed. 如果没有按下按钮 ， 他们在一个非常低功耗的睡眠模式，在这种几乎没有电流消耗的。 The processor wakes up to transmit the appropriate IR command only when a key is pressed. 该处理器唤醒转交相应的红外命令只有当一个键被按下。
Quartz crystals are seldom used in such handsets. 石英晶体很少使用这种手机。 They are very fragile and tend to break easily when the handset is dropped. 他们非常脆弱 ， 往往容易折断 ， 当手机被丢弃。 Ceramic resonators are much more suitable here, because they can withstand larger physical shocks. 陶瓷谐振器更适合这里，因为他们能承受更大的物理冲击。 The fact that they are a little less accurate is not important. 事实上 ， 他们是有点不太准确 ， 并不重要。
The current through the LED (or LEDs) can vary from 100mA to well over 1A! 通过发光二极管（或LED电流）可以改变从100mA至超过1A条！ In order to get an acceptable control distance the LED currents have to be as high as possible. 为了获得一个可以接受的控制距离的LED电流要尽可能高。 A trade-off should be made between LED parameters, battery lifetime and maximum control distance. 权衡之间应作出的LED参数，电池寿命和最大控制距离。 LED currents can be that high because the pulses driving the LEDs are very short. Average power dissipation of the LED should not exceed the maximum value though. LED电流可以是昂贵的 ， 因为脉冲驱动LED很短。平均LED的功耗不得超过最高值 ， 但。 You should also see to it that the maximum peek current for the LED is not exceeded. 您还应该看到它的最高偷看的LED电流不超过。 All these parameters can be found in the LED's data sheet. 所有这些参数可在LED的数据资料。
A simple transistor circuit can be used to drive the LED. 一个简单的晶体管电路可用于驱动LED。 A transistor with a suitable HFE and switching speed should be selected for this purpose. 带有合适的HFE的晶体管的开关速度和应选择达到这一目的。
The resistor values can simply be calculated using Ohm's law. 电阻值可以简单地计算欧姆定律。 Remember that the nominal voltage drop over an IR LED is approximately 1.1V. 请记住 ， 通过一个红外发光二极管的额定电压约为1.1V的下降。

The normal driver, described above, has one disadvantage. 正常的驱动程序，如上所述，有一个缺点。 As the battery voltage drops, the current through the LED will decrease as well. 当电池电压下降，通过LED的电流将减少。 This will result in a shorter control distance that can be covered. 这将导致在较短的控制距离 ， 可以被包括在内。
An emitter follower circuit can avoid this. 射极跟随器电路可避免这种情况。 The 2 diodes in series will limit the pulses on the base of the transistor to 1.2V. 在系列二二极管将限制对晶体管的基极1.2V的脉冲。 The base-emitter voltage of the transistor subtracts 0.6V from that, resulting in a constant amplitude of 0.6V at the emitter. 该基地发射极晶体管的电压减去从0.6V，因此在一个0.6V的固定振幅所引起的发射器。 This constant amplitude across a constant resistor results in current pulses of a constant magnitude. 这在固定电阻结果固定振幅的大小恒定电流脉冲。 Calculating the current through the LED is simply applying Ohm's law again. 通过计算LED的电流只是用欧姆定律了。

The Receiver 接收器
Many different receiver circuits exist on the market. 许多不同的接收电路存在于市场。 The most important selection criteria are the modulation frequency used and the availability in you region. 最重要的选择标准是调制频率的使用和您提供的地区。

In the picture above you can see a typical block diagram of such an IR receiver. 在上面的图片可以看到这样一个红外接收器的典型框图。 Don't be alarmed if you don't understand this part of the description, for everything is built into one single electronic component. 不要惊慌 ， 如果你不明白这说明部分，每一件事都是为一个单一的电子元件。
The received IR signal is picked up by the IR detection diode on the left side of the diagram. 接收到的红外信号拾取上图的左边红外探测二极管。 This signal is amplified and limited by the first 2 stages. 这个信号放大 ， 由第2阶段的限制。 The limiter acts as an AGC circuit to get a constant pulse level, regardless of the distance to the handset. 在限充当AGC电路得到一个恒定脉冲水平，无论距离手机。
As you can see only the AC signal is sent to the Band Pass Filter. 正如你只能看到交流信号发送到带通滤波器。 The Band Pass Filter is tuned to the modulation frequency of the handset unit. Common frequencies range from 30kHz to 60kHz in consumer electronics. 带通滤波器的调谐到手机部门的调制频率。共同从30kHz的频率范围在消费电子60kHz。
The next stages are a detector, integrator and comparator. 下一个阶段是一个探测器，集成商和比较。 The purpose of these three blocks is to detect the presence of the modulation frequency. 这三个区块的目的是检测的调制频率的存在。 If this modulation frequency is present the output of the comparator will be low. 如果这调制频率是目前比较器输出将很低。
As I said before, all these blocks are integrated into a single electronic component. 正如我以前说过，所有这些模块都集成到一个单一的电子元件。 There are many different manufacturers of these components on the market. 目前市场上这些组件的许多不同的制造商。 And most devices are available in several versions each of which are tuned to a particular modulation frequency. 和大多数设备都可以在每个调谐到一个特定的调制频率的多个版本。
Please note that the amplifier is set to a very high gain. 请注意 ， 放大器被设置为一个非常高的增益。 Therefore the system tends to start oscillating very easily. 因此 ， 系统往往很容易起振。 Placing a large capacitor of at least 22µF close to the receiver's power connections is mandatory to decouple the power lines. 配售至少22μF接近接收器的电源连接大电容是强制性的去耦的电源线。 Some data sheets recommend a resistor of 330 Ohms in series with the power supply to further decouple the power supply from the rest of the circuit. 一些数据表推荐的330与电源系列欧姆的电阻 ， 以进一步分离 ， 从赛道的其他部分的电力供应。
There are several manufacturers of IR receivers on the market. Siemens, Vishay and Telefunken are the main suppliers here in Europe. 有红外接收器的一些制造商在市场上。西门子，Vishay与德律风根的主要供应商在欧洲。 Siemens has its SFH506-xx series, where xx denotes the modulation frequency of 30, 33, 36, 38, 40 or 56kHz. 西门子的SFH506 - xx系列，其中xx表示30，33，36，38，40或56kHz的调制频率。 Telefunken had its TFMS5xx0 and TK18xx series, where xx again indicates the modulation frequency the device is tuned to. 德律风根有其TFMS5xx0和TK18xx系列，其中xx再次表明了调制频率的设备调到。 It appears that these parts have now become obsolete. 看来 ， 这些部分已经过时。 They are replaced by the Vishay TSOP12xx, TSOP48xx and TSOP62xx product series. 他们所取代日前，Vishay TSOP12xx，TSOP48xx和TSOP62xx产品系列。
Sharp, Xiamen Hualian and Japanese Electric are 3 Asian IR receiver producing companies. 夏普，厦门华联和日本电气有3亚红外接收器生产公司。 Sharp has devices with very cryptic ID names, like: GP1UD26xK, GP1UD27xK and GP1UD28xK, where x is related to the modulation frequency. Hualian has it's HRMxx00 series, like the HRM3700 and HRM3800. 夏普已经非常神秘ID名称，如设备：GP1UD26xK，GP1UD27xK和GP1UD28xK，其中x是有关调制频率。华联有它是HRMxx00系列一样HRM3700和HRM3800。 Japanese Electric has a series of devices that don't include the modulation frequency in the part's ID. 日本电气公司的设备 ， 不包括在该部分的ID调制频率系列。 The PIC-12042LM is tuned to 36.7kHz, and the PIC12043LM is tuned to 37.9kHz. 事先知情同意，12042LM的调整 ， 以36.7kHz，而PIC12043LM是调整以37.9kHz。
The End? 结束？
This concludes the theory of operation for IR remote control systems intended for use in consumer electronics. 到此结束运作红外遥控器用于消费电子产品使用的系统理论。 I realise that other ways exist to implement IR control, but I will limit myself to the description above. One of the issues not covered here is security. 我知道其他方法存在执行红外控制，但我会限制我上述的描述。这里没有涉及的问题之一是安全。 Security is of no importance if I want to control my VCR or TV set. 安全是如果我想控制我的录像机或电视机并不重要。 But when it comes to opening doors or cars it literally becomes a 'key' feature! 但是 ， 当涉及到开门或汽车字面成为'关键'功能！ Maybe I will cover this issue later, but not for now. 也许我将涉及这一问题后，但不是现在。
I also realise that my small list of manufacturers is far from being complete. 我也明白我的少数制造商名单远未完成。 It is hardly possible to list every manufacturer here. 这几乎是不可能列出所有的厂商都在这里。
This page only described the basic theory of operation of IR remote control. 本页面只介绍了红外遥控器操作的基本理论。 It did not describe the protocols that are involved in communication between transmitter and receiver. 它没有说明是在发射器和接收器之间的沟通 ， 参与协议。 Many protocols are designed by different manufacturers. 许多协议是由不同制造商的设计。 You can find the protocols of some manufacturers in the link section at the top of this page. 你可以找到在这个页面顶部的链接 ， 在一些制造商的部分协议。
ITT Protocol ITT公司协议
The ITT IR protocol is a very old one. 在ITT公司红外协议是一个非常古老的一个。 It differs from other protocols in that it does not use a modulated carrier frequency to send the IR messages. 它不同于它不使用载波频率调制的红外发送邮件从其他协议。 A single command is transmitted by a total of 14 pulses with a width of 10µs each. 一个命令是经由14脉冲的宽度为10μs的每一个条目。 The command is encoded by the distance between the pulses. 该命令编码脉冲之间的距离。
This protocol is very reliable and consumes very little power ensuring long battery life. 这个协议是非常可靠 ， 功耗极低 ， 确保电池寿命长。
Many consumer electronics brands used this protocol in Europe. 许多消费电子品牌在欧洲使用这一协议。 Among them were: ITT, Greatz, Schaub-Lorenz, Finlux, Luxor, Salora, Oceanic and later also Nokia, to name but a few. 其中有：ITT公司，Greatz，绍布，洛伦茨，Finlux，卢克索，萨洛拉，海洋 ， 后来还诺基亚，仅举几个例子。
Features 特征
· Only 14 very short IR pulses per message 很短的只有14红外脉冲每封邮件
· Pulse distance encoding 脉冲距离编码
· Long battery life 长的电池寿命
· 4 bit address, 6 bit command length 4位地址，6位指令长度
· Self calibrating timing, allowing only simple RC oscillator in the transmitter 自校准时间，只允许简单的RC振荡器的发射机
· Fast communication, a message takes from 1.7ms to 2.7ms to transmit 快速沟通，信息传递时间从1.7ms到2.7ms
· Manufacturer Intermetal, now Micronas 制造金属间，现在Micronas公司
Protocol 协议

An IR message is transmitted by sending 14 pulses. 红外线传输的信息通过发送14个脉冲。 Each pulse is 10µs long. 每个脉冲10us的长。 Three different time intervals are used to get the message across: 100µs for a logic 0, 200µs for a logic 1 and 300µs for the lead-in and lead-out. 三种不同的时间间隔用于获取的讯息：为逻辑0，为逻辑1和率先300μs200μs在100μs和铅出。

The preliminary pulse is used by the receiver to set the gain of the amplifier. 初步脉冲接收器所使用的设置放大器的增益。 Then follows a lead-in delay of 300µs, after which the starting pulse is given. 接着他就率先在300μs延迟，之后开始脉冲给出。 The first bit sent is always logic 0, which has a delay duration of 100µs. 第一派位总是逻辑0，则有一100μs延误时间。 This start bit can be used to calibrate the timing of the receiver. 这起始位 ， 可用于校准接收器的时间。 After the start bit follow 4 bits (MSB first) that represent the address of the message. 起始位后 ， 按照4位（MSB在前），它们代表了该邮件的地址。 After that a total of 6 bits (MSB first) for the command are transmitted. 之后 ， 一共有6位（MSB在前）的命令传输。 A trailing pulse should follow this command. 尾随脉冲应遵循此命令。 Finally another 300µs delay follows before the very last pulse, functioning as a lead-out. 最后一个300μs延迟按之前的最后的脉搏，作为主导运作了。
There are a few things the receiving software can check to verify the validity of the received message. 有几件事接收软件可以检查核实收到的邮件的有效性。 The lead-out interval should be 3 times longer than the start bit time, which has a duration of 100µs. 牵头超时间隔应该是3倍的起始位时间较长，有100μs时间。 Bit times should not be off by more than ±20% of the start bit length for logic 0s, or 2x the start bit length for logic 1s. 位时间不应该把超过± 20逻辑为0，或2倍的逻辑1秒的长度开始启动位位长度％。
Don't keep waiting for pulses after 360µs after the