PIC16F688-I/SL Microchip Technology Inc., PIC16F688-I/SL Datasheet - Page 68

• Manufacturer Part Number: PIC16F688-I/SL
• Description: 14 PIN, 7 KB FLASH, 256 RAM, 12 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F688-I/SL

• A/d Inputs: 8-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 12
• Interface: USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 14-pin SOIC-N
• Programmable Memory: 7K Bytes
• Ram Size: 256 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC16F688
8.1
When configuring and using the ADC the following
functions must be considered:
• Port configuration
• Channel selection
• ADC voltage reference selection
• ADC conversion clock source
• Interrupt control
• Results formatting
8.1.1
The ADC can be used to convert both analog and digital
signals. When converting analog signals, the I/O pin
should be configured for analog by setting the associated
TRIS and ANSEL bits. See the corresponding Port
section for more information.
8.1.2
The CHS bits of the ADCON0 register determine which
channel is connected to the sample and hold circuit.
When changing channels, a delay is required before
starting the next conversion. Refer to Section 8.2
“ADC Operation” for more information.
8.1.3
The VCFG bit of the ADCON0 register provides control
of the positive voltage reference. The positive voltage
reference can be either V
source. The negative voltage reference is always
connected to the ground reference.
8.1.4
The source of the conversion clock is software select-
able via the ADCS bits of the ADCON1 register. There
are seven possible clock options:
• F
• F
• F
• F
• F
• F
• F
The time to complete one bit conversion is defined as
T
as shown in Figure 8-3.
DS41203C-page 66
AD
Note:
OSC
OSC
OSC
OSC
OSC
OSC
RC
. One full 10-bit conversion requires 11 T
(dedicated internal oscillator)
/2
/4
/8
/16
/32
/64
ADC Configuration
PORT CONFIGURATION
Analog voltages on any pin that is defined
as a digital input may cause the input
buffer to conduct excess current.
CHANNEL SELECTION
ADC V
CONVERSION CLOCK
OLTAGE REFERENCE
DD
or an external voltage
AD
periods
For correct conversion, the appropriate T
must be met. See A/D conversion requirements in
Section 14.0 “Electrical Specifications” for more
information. Table 8-1 gives examples of appropriate
ADC clock selections.
Note:
Unless using the F
system clock frequency will change the
ADC
adversely affect the ADC result.
clock
© 2006 Microchip Technology Inc.
frequency,
RC
, any changes in the
AD
which
specification
may