Can i connect the RGB5:6:5 signal from ARM CPU directly to a LCD panel and a ADV7123 to display same contents at same times without any buffer IC?
the ARM CPU LCD controller timing conditions :
You can add series damping resistors on the path of the RGB565 digital data to maintain the characteristic impedance of the PCB tracks. The series damping resistors will reduce the reflections on the signal lines. I suspect that at lower clock frequencies (lower resolutions say VGA/WVGA) you might just get away with this kind of arrangement. At higher frequencies this might become an issue that noise will be introduced in the data (RGB565).
Could you please elaborate your requirement clearly to understand it?
If you can provide the details in the form of block diagram then I believe that it would be easy to extract it. Thanks for understanding.
With respect to the ADV7123 in your design: the ADV7123 is a video DAC that outputs analog values based on the digital input applied.
is my understanding correct that you are connecting the RGB565 to drive the panel digitally at the same time that you have connected the RGB565 to the digital inputs of the ADV7123?
Can you be more specific as to what you intend doing? I see that your output load capacitance min is either 3/5 pF and the max is 30/60 pF; for the ADV7123 the input capacitance is typically 10pF. Can you guarantee that your output load capacitance can be within the 10pF? Can you guarantee noise reflections not happening?
If that you intend to drive an LCD panel and at the same time you are using the analog outputs of the DAC to control some other device based on the RGB565 data input, then you have to be careful as this might lead to reflections at the points you have connected to the LCD and back to the inputs of the DAC (RGB565) at higher frequencies.
Yes, I want to drive an LCD panel and a VGA monitor at the same time. The output load capacitance is 5-60pF, the ADV7123 input capacitance is 10pF, the output capacitance range covers the input capacitance, why i should guarantee the output load capacitance within the 10pF?
I can't guarantee noise reflections not happening, that is what i worry about. What can i do to reduce noise reflections? Like add a buffer?
I am connecting the RGB565 to drive the panel digitally at the same time that i has connected the RGB565 to the digital inputs of the ADV7123(analog output to VGA).
The CPU output load capacitance is 5~60pF, the ADV7123 input capacitance is 10 pF. Can i use the CPU drive this two devices at the same time?
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