430学习（430 study）.docVIP

430学习（430 study） MSP430 DC AC measurement technology [link] Based on replication Honghu . Administrators On the door Add friends Say hello Send a message . Direct lift The landlord Published in the 2012-7-2 08:34:53 | only see the author | reverse browse Functional design requirements (range): DC voltage (DCV) - 200 mV 2V 20V 200V 1000V AC voltage (ACV) -- 200mV 2V 20V 200V 700V Direct current (DCA) - 2mA 20mA 200mA 20A Alternating current (ACA) -- 2mA 20mA 200mA Resistance (OHM) -- 2K 20K 200K 2M20M 200 Three, the main chip: MSP430FE42X Four, operation: Button - DCV key, ACV key, DCA key, ACA key, OHM key Five, principle diagram: 135510.gif (10.53 KB, download number: 0) Five, measurement principle: When the AD measure, MSP430FE42X can choose an external reference source, can also choose the internal reference. Here in the measurement of voltage and current, selection of internal reference 1.25V, so when the external voltage measured at 0.625V, AD sampling value is 65535, when the measured voltage is 0.625 AD when the sampling value is 0. Since the minimum range design for 0.2V, so it needs to be enlarged to 0.625V, the full range, and then convert that 0 - 20000 digit display according to the corresponding 0-32767. The actual minimum resolution is 0.2/32767V = 6 v. When the voltage to be measured is greater than 0.2V, must be divided into pressure treatment, generally use 10 times the divider to 0.2V such as 2V. The voltage divider is shown in figure 1. 135859.jpg (27.34 KB, download number: 0) Similarly, when measuring the current, but also to make treatment, current into voltage, then measuring. The current measurement principle diagram as shown in figure 2. 140728.jpg (24.71 KB, download number: 0) Please note that in Figure 2 on the right side of the 20A input is directly connected to the fuse of course can also add a 20A. The above is the measurement of DC voltage or DC current, when measuring AC voltage or AC current, must carry out rectification, the rectif