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EIAJ格式即是SONY格式,我从国外的网上看到这样一个电路,可以将EIAJ格式转I2S格式,本人不是很懂这些,重新画了图,也将英文翻译了一下,翻译得肯定不准确。请高手们看看,这个电路可行吗?
I designed this circuit to drive a TDA1541 DAC from the EIAJ of a Sony servo controller chip ( CXD1135 ).
我设计这个电路来驱动从一个索尼伺服控制器芯片来的EIAJ信号(CXD1135)到TDA1541。
Other common ones are CXD2500 etc etc. Depending on the way they are programed, some Philips servo controller also outputs EIAJ signals instead of I2S.
其他常见的是CXD2500等等,依照他们的语法方式不同,有些飞利浦伺服控制器也输出EIAJ信号,而不是输出I2S的。
Usually this is because a EIAJ input DAC such as TDA1545 or TDA1543A were used.
通常这是因为,如TDA1545或TDA1543A采用EIAJ信号输入。
To converter EIAJ to I2S, we need to delay the LRCLK signal by 7 BCK cycles, and invert it.
在转EIAJ至I2S,我们需要用BCK信号将LRCLK延迟了7个周期并反相。
This is easily accomplished with NOT gates, and a 7 bit shift register.
这是用非门和7位的移位寄存器很容易实现。
I have implemented this circuit as per the schematics below.
我已经实现按以下的这个电路的原理图。
BCK needs to be inverted as the 74HCT374 is positive edge triggerred, and used to clock the shift register.
BCK需要反相当74HCT374是正向的边缘触发,用移位寄存器的时钟。
LRCLK is inverted three times, to get the right phase, and to delay it by 2 more gates propagation delaty as compared to the shift register clock signals so that the data is valid during the clock edge.
LRCLK倒相三次,得到正确的相位,并推迟了2个门传输,相比于移位寄存器的时钟信号,使数据在有效时钟边沿。
I have run out of gates, and hence did not buffer the data signal.
我已经用完了大门,因此并没有缓冲的数据信号。
That can be easily accomplished by using another two NOT gates.
可以很容易地通过使用另外两个非门。
But that would mean that I need another 74HCT04.
但那就意味着,我需要另一个74HCT04。
I took the easy way out and did not bother.
我带着简单的方法了,没有理会。
If you are driving long cables, or are driving several DACs ( parallel DAC for example ), it is good practice to buffer the data signal.
如果你用长电缆,或驱动(例如并行DAC)几个数模转换器,对于缓冲区中的数据信号它是很好的做法。
This also prevents you killing your expensive servo controller or CS8412 if you scr*w up something.
这也防止你搞死昂贵的伺服控制器或CS8412如果。。。。一些事情
The circuit had been tested on TDA1543 ( 4 in parallel ) with no problems.
该电路已进行了测试TDA1543(4并联),没有任何问题。
However, with the TDA1541, there is some background noise.
然而,随着TDA1541,有一些背景噪音。
This noise is reduced significantlly when 100 ohm resistors are connected in series with the signals to damp the ringing.
这种噪声大为降低,当用100欧姆的电阻是串行数据线中,抑制振荡。 |
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