I can used the analog/digital conversor with signals negatives and positive (e.g. signal sin) in the mM-509. This is have the register of 8051.
Is the mM-509 an 8051? No? Then, no, there is no register in the 8051 for an external device. At best it's memory mapped. At worst you have to write a protocol to get the data from it. - Mark
Is your mM-509 made by Phytec? Its from Phytec then the input voltage range the same as for the C509 Controller from Infineon. Vinmin = Vagnd Vinmax = Varef 4V <= Varef <= Vcc + 0.1V and Vss - 0.1V <= Vagnd <= Vss + 0.2V So you can not use it for negative input voltages without any additional extern circuits! Andreas Haack