The typical signal isolation is the photoelectric isolation. Using PV isolation to separate the input of the single-chip device from the output of that. On the one hand, interference signals can not enter the single-chip microcomputer system, and on the other hand, the noise of single-chip system itself will not be a way to transfer as conduction. And the shielding is used to isolate the space radiation. As for the part with loud noise such as the switching power supply, you need to cover them up with a metal box, so it can reduce the interference to the single-chip microcomputer system brought by noise sources. As for the analog circuit which is afraid of interference particularly, for example, high-sensitive weak signal amplification circuit could be shielded .But the important point is that metal shielding itself must be connected with the real ground.
As for D/A, this is described in D/A conversion rate as an important parameter in describing D/A conversion rate, and generally it refers to the period of time when digital input is inputted and analog output stability is within the normal accuracy. As for A/D, because of the importation of electronic switches, amplifiers have a delay. So a change in inputting voltage to the A/D will take some time to be provided for the accuracy and stability.
Resolution: The resolution of the card is 12, which means it's the smallest full-scale resolution to quantify the whole range (plus or minus range) of 1/4096 (2 of 12 power per 1), however, in the actual software, for the convenience of dealing, the data do need to be mapped to 16-bit, high- 4.
The A/D board has high input impedance. The value of the input impedance can be 10M-1G . At the same time, there is no resistance between the channel and the ground. So the signal input value can not be zero. To solve the problem, we can connect the vacant channels to the ground or put a 1K-1M resistance between the vacant channels and the ground . It certainly will not affect the signal input channel. So if it is not necessary to show the data from the vacant channels, users do not need to care about them.