
Rev. 1.7
33
C8051F310/1/2/3/4/5/6/7
1.7.
10-Bit Analog to Digital Converter
The C8051F310/1/2/3/6 devices include an on-chip 10-bit SAR ADC with a 25-channel differential input
multiplexer. With a maximum throughput of 200 ksps, the ADC offers true 10-bit accuracy with an INL of
±1LSB. The ADC system includes a configurable analog multiplexer that selects both positive and nega-
tive ADC inputs. Ports1-3 are available as an ADC inputs; additionally, the on-chip Temperature Sensor
output and the power supply voltage (VDD) are available as ADC inputs. User firmware may shut down the
ADC to save power.
Conversions can be started in six ways: a software command, an overflow of Timer 0, 1, 2, or 3, or an
external convert start signal. This flexibility allows the start of conversion to be triggered by software
events, a periodic signal (timer overflows), or external HW signals. Conversion completions are indicated
by a status bit and an interrupt (if enabled). The resulting 10-bit data word is latched into the ADC data
SFRs upon completion of a conversion.
Window compare registers for the ADC data can be configured to interrupt the controller when ADC data is
either within or outside of a specified range. The ADC can monitor a key voltage continuously in back-
ground mode, but not interrupt the controller unless the converted data is within/outside the specified
range.
Figure 1.15. 10-Bit ADC Block Diagram
10-Bit
SAR
ADC
Timer 1 Overflow
CNVSTR Input
Timer 3 Overflow
(+)
(-)
Configuration, Control, and Data Registers
23-to-1
AMUX
Temp
Sensor
23-to-1
AMUX
VDD
P1.0
P1.7
P2.0
P2.7
GND
P1.0
P1.7
P2.0
P2.7
P3.0
P3.4
P3.0
P3.4
P3.1-3.4
available on
C8051F310/2
P3.1-3.4
available on
C8051F310/2
Analog Multiplexer
Timer 0 Overflow
Timer 2 Overflow
Start
Conversion
000
AD0BUSY (W)
001
010
011
100
101
16
Window Compare
Logic
Window
Compare
Interrupt
ADC Data
Registers
End of
Conversion
Interrupt
P1.6, P1.7 available on
C8051F310/1/2/3/4/5
P2.6, P2.7 available on
C8051F310/1/2/3/4/5
P1.6, P1.7 available on
C8051F310/1/2/3/4/5
P2.6, P2.7 available on
C8051F310/1/2/3/4/5
VREF