I<sup>2</sup>C逻辑电路，使技术更趋成熟- 恩智浦半导体厂商_在线座谈

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主题:I2C逻辑电路，使技术更趋成熟
在线问答:
[问：cztyh]	i2c接口器件在读命令中是否一定需要非应答信号？
[答：Vincent]	不強制要求但如果能implement, 會更好	[2003-11-27 10:35:43]
[问：happytiao]	I2C总线允许多个器件挂接而且数据流是双向的，当多个从件分别与主件通信的时候，如何保证从件之间的数据不会相互干扰呢？如何阻止数据从一个从件流到另一个从件呢？谢谢
[答：Vincent]	The I2C master talk with one slave device one time. The other slave device can not listen the communication	[2003-11-27 10:45:14]
[问：wood007_friend]	PCF8574 和 PCF8574A 有什么区别？可以直接替代么？
[答：Vincent]	The different between PCF8574 and PCF8574A is that the I2C slave address is different.You can use PCA9554 to replace PCF8574, PCA9554A to replace PCF8574A	[2003-11-27 10:47:20]
[问：hookel]	带宽可以动态分配吗?可以设定优先级吗?以可以使突发的事件得到及时处理?
[答：Vincent]	帶寬無法動態分配.	[2003-11-27 10:50:31]
[问：康]	请问，I2C连线一般可以达到多长？
[答：Vincent]	在一般狀況下, 可以達到 3 meters (10 feet)	[2003-11-27 10:55:58]
[问：ecnanjing_EBY7E]	I2C总线一开始用于本地内部总线连接，今天介绍I2C总线可用于高速的数据通讯。请问这时的数据容量和安全性如何，传输距离有多长？
[答：Timothy]	I2C 並無安全性問題,傳輸距離可參照本次資料第六頁	[2003-11-27 11:04:39]
[问：lyf]	1）最多能支持多少从端。500个行否？2）传送的距离。多少米？3）最高传送速率，与距离有关吗？4）数据传送的可靠性有措施保证否？
[答：Vincent]	1. 如果要支持500 個從端, 需要一些I2C 器件來達成.2. 一般情況下, 3 meters is OK3. 有關4. 無法保證傳輸的可靠性. I2C spec 沒有規範可靠性這方面的問題	[2003-11-27 11:06:05]
[问：smart_bear]	PHILIPS是否会修改目前的规范，使得I2C具有更高的传输速度和传输距离
[答：Bennett]	The I2C specification is controlled by the I2C committee and I don"t believe that transmission speeds greater than 3.4 MHz are needed for current implementations. Bus Buffers like the P82B96 allow longer distance transmissions.	[2003-11-27 11:07:09]
[问：kfawj]	这种总线方式当高原的山洞、汽车、甚至是当汽车穿越山洞应用时，会不会造成一些传输干扰（或是说产生错误)?谢谢！
[答：Vincent]	No	[2003-11-27 11:07:36]
[问：smart_bear]	PHILIPS是否希望I2C成为廉价的，可与USB共存的PC通用端口
[答：Bennett]	I2C and USB have very different bandwidths and uses. UBS is more for high speed data. I2C is more for maintenance and control applications that need low bandwidth. Some customers are starting to use I2C however for faster control of more devices and therefore need more bandwidth on the bus. The price of I2C components have been coming down and as I2C becomes more popular with numberious manufactuers making devices the prices will continue to decrease.	[2003-11-27 11:13:34]
[问：johnzhou]	对于把I^2 C集成在其它一些芯片中有没有打算，不知打算集成在那些芯片里面呢？I^2 C会不朝大容量方面发展？
[答：Timothy]	市面上已有一些I2C芯片,如microcontrollor, EEPROM..., 當然我們也會開發更多新的芯片,也希望您能提供寶貴的意見,大容量的IC, yes, already in developement	[2003-11-27 11:15:15]
[问：zlj_sky]	I2C逻辑电路的传输速度不是很快，请问在编程过程中如何更好的进行抗干扰设计？还有在不同的传输速率下共用一个I2C是否符合设计原则？
[答：Vincent]	編程方式無法解決干擾一個I2C Bus 下可以有不同傳輸速率的從端共存	[2003-11-27 11:16:41]
[问：alex_fn]	我想知道在多主时的仲裁处理，以及使用那些器件可以安全快速的完成多主的操作
[答：Bennett]	Per the I2C specification, all masters should be multi master capable but in reality, many masters are not. Masters are typically microcontrollers, DSPs, ASICs or FPGAs and you must look at the data sheet or talk with the manufacturere to determine if they are multiple master capable. Philips will announce the PCA9541 on Monday. It is a 2 to 1 master selection that combines two masters to one slave for situations where the masters are not multiple master capable.	[2003-11-27 11:18:21]
[问：dmx152]	有没有从I^2C总线到RS-232的转换芯片。
[答：Vincent]	So far, we have no I2C to RS232 device.We have plan to do the device. But no schedule yet.	[2003-11-27 11:18:33]
[问：yeyuguo]	could users define the address of I2C devices they design by themselves?
[答：Vincent]	Most Philips I2C device has 2 to 3 address pin to program (hardware setting).	[2003-11-27 11:20:05]
[问：fangneu]	SDA上传输的是一个8位的数据流吗？
[答：Vincent]	Yes	[2003-11-27 11:20:30]
[问：smart_bear]	光隔离后的I2C的传输距离是多少
[答：Bennett]	The distance should be less than the 400 pF limit which is about 3 meters or 10 ft of wire.	[2003-11-27 11:20:54]
[问：samire]	如何选择总线扩展器?它的主要依据是什么?
[答：Timothy]	請至http://www.philipslogic.com/support/appnotes/參照AN469,有詳細的介紹	[2003-11-27 11:22:54]
[问：sq2003]	由于I2C总的驱动电容值是一定的,请问如何去估算总线上已有的容值?谢谢!
[答：Vincent]	無法估算總線上的容值可以由I2C 信號的波形觀測, 只要符合I2C 規範中對rise time and fall time 的要求即可	[2003-11-27 11:25:06]
[问：xyzd-2001]	The LPT-to-I2C host adapter with serial EEPROM is also shipped with this tool.I want to know whether it adapter to the RPROM?
[答：Bennett]	I"m not sure exactly what the question is.The Win-I2CNT parallel to I2C adapter has an EEPROM on the board. It is a serial EEPROM and communicates with the I2C bus on the adapter board. The I2C jack on the board is used to communicate with I2C devices not on the board.	[2003-11-27 11:28:30]
[问：guanfree]	I2C的从件数量有什么限制吗？谢谢。
[答：Timothy]	To meet timing considerations the maximum allowable bus capacitance is 400 pF which is about 20 – 30 devices	[2003-11-27 11:33:50]
[问：flyingheart]	iic接口的eeprom经常有数据被意外窜改的现象，该如何有效避免？
[答：Vincent]	可使用eeprom 上的write proection pin 預防竄改	[2003-11-27 11:38:04]
[问：hjh002]	如何从软件上提高I2C电路的抗干扰性能？
[答：Vincent]	若要以軟件方式解決, 需要以較多的編程去確認傳送資料無誤	[2003-11-27 11:41:06]
[问：ljp]	采用P82B96,总线长度能增加多少?驱动能力呢?
[答：Vincent]	Possible distances range from 50 meters at 85 kHz to 1km at 31 kHz over twisted-pair phone cable.	[2003-11-27 11:44:33]
[问：talentren]	master transmitter& slave receiver.slave 如何告知传输完成？一定需要约定传输数目？
[答：Vincent]	當master 與 slave 完成傳輸時, 只需送出 STOP command 即可完成	[2003-11-27 11:46:04]
[问：fjddxx]	I2C的纠错机制是如何的？
[答：Vincent]	I2C 沒有糾錯機制	[2003-11-27 11:47:16]
[问：yeyuguo]	should all the addresses of I2C device be authorized by Philips?
[答：Bennett]	On the I2C homepage of www.semiconductors.philips.com/i2c there is a request page for I2C addresses. It is not required to request an address if you can assign an address from a compariable device (i.e, 8 bit ADC and newer 10 bit ADC).	[2003-11-27 11:49:16]
[问：liulh]	请问I2C总线上最多可以挂接多少个器件？I2C总线标准中说总线电容不超过400PF,那么如何测量总线电容呢？总线电容的大小都取决于那些因素呢？
[答：Timothy]	About 20 – 30 devices, 觀察raise time, fall time來判斷;總線的電容大小與板子走線的容值,以及IC的容值有關	[2003-11-27 11:49:56]
[问：ecnan jing_EBY7E]	一般来说器件的I2C地址是器件制造时就设定好的，如果用MCU的I/O口设计I2C接口时地址设置有何要求？
[答：Vincent]	若是使用MCU, I2C 地址可自定. 只要不與其他從件衝突即可	[2003-11-27 11:50:26]
[问：samire]	多个HUB PCA9518能否串接应用?
[答：Vincent]	可以	[2003-11-27 11:51:31]
[问：ruanhan]	目前IIC接口的EEPROM存储器最大做到多大？
[答：Timothy]	Philips 目前做到(2048*8)16K bit, 編號為PCF85116-3	[2003-11-27 11:53:17]
[问：pf1685]	I2C总线由于数据传输速度较慢，它能够跟上我们以后3G手机所需的高速数据传输的要求吗？
[答：Vincent]	若是要使用在大量的數據傳輸, 目前的I2C 器件無法滿足需求但I2C 規範中, I2C 總線速率可到3.4MHz. Philips 未來會供應high speed I2C 器件	[2003-11-27 11:55:12]
[问：qin]	如果要用长的电缆从MCU传送3.3V I2C到几个从器件板,有什么好的建议或要采用什么样的器件?
[答：Vincent]	You can use Philips P82B96 or P82B715	[2003-11-27 11:55:49]
[问：ecnan jing_EBY7E]	在同一条总线上挂了N个有I2C的器件，当某个器件需主从切换时SCL的频率是否可以同时改变？
[答：Vincent]	可以	[2003-11-27 11:57:59]
[问：haojie]	哪些因素会造成通讯失败？
[答：Bennett]	If the I2C state machines are properly constructed the only real way to fail is if the master stops sending the clock.If the device state machine is not made well it could holds the SDA line low. Well made state machines should clear by sending 9 clock pulses unless the state machine is not made well.Most slaves don"t control the SCL line but if the slave does hold the SCL line low there is no way for the master to clear it and all devices need to be reset.Other ways are bent pins that could hold the SDA or SCL lines low.	[2003-11-27 12:00:25]
[问：ljp]	如何调整I2C LED闪光器的闪光周期?
[答：Vincent]	可從LED閃光器內的PWM 0或1 register 調節	[2003-11-27 12:01:57]
[问：cn_kendall]	I2C毕竟没用RS232的链路层内容多。如果我的I2C总线上还挂有许多EEPROM，也是I2c的，而且总线控制器地址被其中单元包括，没有更多的地址可以使用了，如何避免系统冲突。谢谢！
[答：Vincent]	可使用Philips I2C multiplexer (PCA9540 或PCA9544) 解決衝突的問題	[2003-11-27 12:04:07]
[问：reporter]	Hi Vincent, one question ... Can Dimmer create the "Blinking" effect ?
[答：Vincent]	Yes, The Dimmer support 160Hz frequency. And the blink effect only need 40Hz frequency.	[2003-11-27 12:06:07]
[问：pf1685]	是不是所有的具有I2C总线的芯片都既可以作为Master，也可以作为Slave?
[答：Bennett]	Chips with an I2C interface can be either a master, slave or master and slave depending on what is required and how they are made.Devices like ADC or GPIO are only slaves.Microcontrollers can be master or slave.The key is that the master sends the clock pulse so if the device can"t control the SCL line it can never be a master.	[2003-11-27 12:09:02]
[问：qin]	能工作400kHz的I2C器件有那些Philips 器件?
[答：Timothy]	Philips擁有多個不同的產品線,因此可支援400KHz的產品也很多,以特殊邏輯器件來說,幾乎都可以做到,而microcontrollor來說,則有LPC2104, 2105, 2106, P89LPC920...	[2003-11-27 12:10:34]
[问：jxhml]	那如果我系统需要一个监听ｉ２ｃ总线上的数据传输情况，应该如何考虑方案？
[答：Vincent]	My suggestion is MCU	[2003-11-27 12:11:56]
[问：qin]	能否给出I2C总线频率与距离的关系?
[答：Bennett]	There are certain capacitance limits for different frequencies.At 3.4 Mhz the limit is about 150 pF which would be 3 feet.The limit at 400 kHz and 100 kHz is 400 pF which is about 10 feet.As the length gets longer the capacitance gets bigger and you can"t meet the timing restrictions.It is possible to reduce the frequency and go longer distances.The P82B96 bus buffer has a stronger driver and allows 71KHz at 100 meters.	[2003-11-27 12:18:07]
[问：raiky_wu]	I2C逻辑电路广泛应用于各个领域，您认为他最成功的，或者最有前途的是那个领域？
[答：Bennett]	I2C is mostly used for maintenance and control functions in many different kinds of equipment.Probably PC, notebooks, servers using SMBus (similar to I2C) are the most successful areas.	[2003-11-27 12:19:24]
[问：bluemarble]	在大批量数据传输的嵌入式系统开发中，I2C有什么优势？
[答：Timothy]	Can reduces the size and cost of ICs based on the I2C Bus since far fewer pins are used. Additionally, far fewer wires or copper traces are needed for inter-chip communications and the circuit boards are greatly reduced in size, complexity and cost.	[2003-11-27 12:21:33]

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