I/O Pins Used With Adc Function; Idle And Power-Down Mode; How To Improve Adc Accuracy - CMOSTEK CMT2380F17 Manual

ADRJ
ADC Data Resolution
0
1

26.2.9 I/O Pins Used with ADC Function

The analog input pins used for the A/D converters also have its I/O port's digital input and output function.
In order to give the proper analog performance, a pin that is being used with the ADC should have its digital
output as disabled. It is done by putting the port pin into the input-only mode. And when an analog signal is
applied to the ADCI7~0 pin and the digital input from this pin is not needed, software could set the
corresponding pin to analog-input-only mode to reduce power consumption in the digital input buffer. The port
pin configuration for analog input function is described in Table 14–3. General Port Configuration Settings and
Section "" and "14.2.1 Port 1 Register".

26.2.10 Idle and Power-Down Mode

If the ADC is turned on in Idle mode and Power-Down mode, it will consume a little power. So, power
consumption can be reduced by turning off the ADC hardware (ADCEN=0) before entering Idle mode and
Power-Down mode.
In Power-Down mode, the ADC does not function. If software triggers the ADC operation in Idle mode,
the ADC will finish the conversion and set the ADC interrupt flag, ADCI. When the ADC interrupt enable
(EADC, EIE1.1) is set, the ADC interrupt will wake up CPU from Idle mode.

26.2.11 How to improve ADC Accuracy

To use ADC measure the voltage, its accuracy might be affected by many factors, for example, the power
noise of the MCU VDD or tolerance of the reference voltage. MG82F6D64/32 has trimmed the internal
reference voltage – IVR under VDD equals to 3.3V, and use the ADC to read its ADC value to store in flash
ROM as the Pre-stored value. To use this value by following formulas to calculate the AIN voltage instead of
measuring VDD to calculate the 1 LSB voltage.

To push back the IVR voltage (which was measured under VDD=3.3V)

o use the proportional relationship calculate the I/O pin voltage
ARES[1:0]
ADC Data Byte Transfer by DMA
00
(12-bit)
01
(10-bit)
1x
(8-bit)
00
(12-bit)
01
(10-bit)
1x
(8-bit)
Rev0.1 | 287/347
Data Transfer Order
DBSD
st
1
0 0xF0
(2-byte Data)
1 0xFF
(1-byte Data)
0 0xC0
(2-byte Data)
1 0xFF
(1-byte Data)
0 0x00
(2-byte Data)
1 0xFF
(1-byte Data)
0 0xFF
(2-byte Data)
1 0xFF
(1-byte Data)
0 0xFF
(2-byte Data)
1 0xFF
(1-byte Data)
0 0xFF
(2-byte Data)
1
0xFF
(1-byte Data)
CMT2380F17
nd
Data 2 Data
0xFF
X
0xFF
X
0xFF
X
0x0F
X
0x03
X
0x00
X
www.cmostek.com