M16C30P_07 Datasheet, PDF (194/317 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/30 SERIES

M16C/30P Group
16. A/D Converter
16.2 Function
16.2.1 Resolution Select Function
The desired resolution can be selected using the BITS bit in the ADCON1 register. If the BITS bit is set to “1”
(10-bit conversion accuracy), the A/D conversion result is stored in the bit 0 to bit 9 in the ADi register (i = 0 to
7). If the BITS bit is set to “0” (8-bit conversion accuracy), the A/D conversion result is stored in the bit 0 to bit
7 in the ADi register.
16.2.2 Sample and Hold
If the SMP bit in the ADCON2 register is set to “1” (with sample-and-hold), the conversion speed per pin is
increased to 28 φAD cycles for 8-bit resolution or 33 φAD cycles for 10-bit resolution. Sample and Hold is
effective in all operation modes. Select whether or not to use the Sample and Hold function before starting A/D
conversion.
16.2.3 Extended Analog Input Pins
In one-shot and repeat modes, the ANEX0 and ANEX1 pins can be used as analog input pins. Use the OPA1 to
OPA0 bits in the ADCON1 register to select whether or not use ANEX0 and ANEX1.
The A/D conversion results of ANEX0 and ANEX1 inputs are stored in the AD0 and AD1 registers,
respectively.
16.2.4 Current Consumption Reducing Function
When not using the A/D converter, its resistor ladder and reference voltage input pin (VREF) can be separated
using the VCUT bit in the ADCON1 register. When separated, no current will flow from the VREF pin into the
resistor ladder, helping to reduce the power consumption of the chip.
To use the A/D converter, set the VCUT bit to “1” (Vref connected) and then set the ADST bit in the ADCON0
register to “1” (A/D conversion start). The VCUT and ADST bits cannot be set to “1” at the same time.
Nor can the VCUT bit be set to “0” (Vref unconnected) during A/D conversion.
Rev.1.22 Mar 29, 2007 Page 178 of 291
REJ09B0179-0122