M16C User Manual.pdf

D-A ConverterMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER2.8 D-A Converter2.8.1 OverviewThe D-A converter used in the M16C/62 group is based on the 8-bit R-2R technique.(1) Output voltageThe D-A converter outputs voltage within a range from 0 V to VREF. The output voltage is determinedby VREF/(256) X the D-A register contents.The D-A converter is not effected by the Vref connection bit of the A-D converter.(2) Conversion timetsu = 3 µs(3) Output from the D-A converter and the direction registerTo use the D-A converter, do not set the direction register of the relevant port to output.(4) Pins related to the D-A converter• DA0 pin, DA1 pin Output pins of the D-A converter• AVcc pinThe power source pin of the analog section• VREF pinInput pin of the reference voltage• AVss pinThe GND pin of the analog section(5) Registers related to the D-A converterFigure 2.8.1 shows the memory map of D-A converter-related registers, and Figure 2.8.2 shows D-Aconverter-related registers.(6) NoteD-A output pins shared with P93 and P94. The two pins are input ports and floating at the reset.03D81603D91603DA1603DB1603DC16D-A register 0 (DA0)D-A register 1 (DA1)D-A control register (DACON)Figure 2.8.1. Memory map of D-A converter-related registersD-A control registerb7 b6 b5 b4 b3 b2 b1 b0Symbol Address When resetDACON 03DC16 0016Bit symbol Bit name Function R WDA0EDA1ED-A0 output enable bitD-A1 output enable bit0 : Output disabled1 : Output enabled0 : Output disabled1 : Output enabledNothing is assigned.In an attempt to write to these bits, write “0”. The value, if read, turns out to be “0”D-A registerb7b0Symbol Address When resetDAi (i = 0,1) 03D816, 03DA16 IndeterminateOutput value of D-A conversionFigure 2.8.2. D-A converter-related registersFunctionR W414