M16C User Manual.pdf

A-D ConverterMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER(4) Functions selection(a) Sample & Hold functionSample & Hold function samples input voltage when A-D conversion starts and carries out A-Dconversion on the voltage sampled. When A-D conversion starts, input voltage is sampled for 3cycles of the operation clock. When the Sample & Hold function is selected, set the operation clockfor A-D conversion to 1 MHz or higher.(b) 8-bit A-D to 10-bit A-D switching functionEither 8-bit resolution or 10-bit resolution can be selected. When 8-bit resolution is selected, the 8higher-order bits of the 10-bit A-D are subjected to A-D conversion. The equations for 10-bit resolutionand 8-bit resolution are given below:10-bit resolution (Vref X n / 2 10 ) – (Vref X 0.5 / 10 10 ) (n = 1 to 1023), 0 (n = 0)8-bit resolution (Vref X n / 2 8 ) – (Vref X 0.5 / 2 10 ) (n = 1 to 255), 0 (n = 0)(c) A-D conversion by external triggerThe user can select software or an external pin input to start A-D conversion.(d) External operation amplifier connection functionThe selected A-D convertor pin input voltage can be output from the ANEX0 pin. By connecting anoperation amplifier between the ANEX1 pin and ANEX0 pin when using this function, the input voltageto all A-D conversion pins can be amplified with one operation amplifier.(e) Expanded analog input pins functionA-D conversion can be done for voltage input from either the ANEX0 pin or the ANEX1 pin.(f) Connecting or cutting VrefCutting Vref allows decrease of the current flowing into the A-D converter. To decrease themicrocomputer's power consumption, cut Vref. To carry out A-D conversion, start A-D conversion 1µs or longer after connecting Vref.The following are exsamples in which functions (a) through (f) are selected:• One-shot mode ......................................................................................................................... P388___________• One-shot mode, trigger by ADTRG ................................................................................................................... P390• One-shot mode, software trigger, expanded analog input........................................................ P392• One-shot mode, software trigger, external operation amplifier connected ............................... P394• Repeat mode, software trigger ................................................................................................. P396• One-shot sweep mode, software trigger................................................................................... P398• Repeated sweep mode 0, software trigger ............................................................................... P400• Repeated sweep mode 1, software trigger ............................................................................... P402383