Jacky Yau wrote:
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I'm going to use ADC0844 which is ADC with 4 channels Multiplexer options. I connect it to port 0. The LCDM is connected to port 1.

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The MOVX instruction is for data bus configurations only. If you have several parallel data bus chips, you may do better moving all the data in and out of the P0 port utilizing P1 with movx a,@Ri commands. I don't know if your LCD module is parallel or serial. Use of the MOVX requires P0, P1 and if 16 bit use, P2.

Since you have the ADC or P0 and an LCD or P1, you probably CANNOT use MOVX.

If you aren't using a data bus configuration than you need to do what we loosely call bit-banging. That roughly means we have to write the commands to make each signal go high and again to go low. This is obviously slower than an automatic read or write cycle that the MOVX provides. There are tradeoffs.

Tell us more about your circuitry and what your design objective is. Do you want to keep it simple for a fast project, or inexpensive over high volume manufacturing, or interesting for hobby and learning.

aka j

http://www.geocities.com/mingpzong