C8051F410/1/2/3
5.3.5. Output Conversion Code
The registers ADC0H and ADC0L contain the high and low bytes of the output conversion code. When the
repeat count is set to 1, conversion codes are represented in 12-bit unsigned integer format and the output
conversion code is updated after each conversion. Inputs are measured from ‘0’ to V
REF
x 4095/4096.
Data can be right-justified or left-justified, depending on the setting of the AD0LJST bit (ADC0CN.2).
Unused bits in the ADC0H and ADC0L registers are set to ‘0’. Example codes are shown in Table 5.1 for
both right-justified and left-justified data.
Table 5.1. ADC0 Examples of Right- and Left-Justified Samples
Input Voltage
V
REF
x 4095/4096
V
REF
x 2048/4096
V
REF
x 2047/4096
0
Right-Justified ADC0H:ADC0L
(AD0LJST = 0)
0x0FFF
0x0800
0x07FF
0x0000
Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
0xFFF0
0x8000
0x7FF0
0x0000
When the ADC0 Repeat Count is greater than 1, the output conversion code represents the accumulated
result of the conversions performed and is updated after the last conversion in the series is finished. Sets
of 4, 8, or 16 consecutive samples can be accumulated and represented in unsigned integer format. The
repeat count can be selected using the AD0RPT bits in the ADC0CF register. The value must be right-
justified (AD0LJST = “0”), and unused bits in the ADC0H and ADC0L registers are set to '0'. The example
in Table 5.2 shows the right-justified result for various input voltages and repeat counts. Notice that
accumulating 2
n
samples is equivalent to left-shifting by
n
bit positions when all samples returned from the
ADC have the same value.
Table 5.2. ADC0 Repeat Count Examples at Various Input Voltages
Input Voltage
V
REF
x 4095/4096
V
REF
x 2048/4096
V
REF
x 2047/4096
0
Repeat Count = 4
0x3FFC
0x2000
0x1FFC
0x0000
Repeat Count = 8
0x7FF8
0x4000
0x3FF8
0x0000
Repeat Count = 16
0xFFF0
0x8000
0x7FF0
0x0000
Rev. 1.0
57
SILABS [ SILICON LABORATORIES ]
