数模转换实验，分两步

带图的DINBITP1.0CLKBITP1.1CSBITP1.2ORG0000HAJMPMAINORG0030HMAIN:MOVR2,#00H;串行高四位MOVR3,#00H;串行低八位COME1:CLRCSMOVR0,#4;串行高四位计数MOVA,R2LCALLLOOP;送串行数据MOVR0,#8MOVA,R3LCALLLOOPMOVA,R3ADDA,#05HMOVR3,ACLRCLKSETBCSCJNER3,#2