PIC16C770-I/SO Microchip Technology, PIC16C770-I/SO Datasheet - Page 117

• Manufacturer Part Number: PIC16C770-I/SO
• Description: IC MCU OTP 2KX14 A/D PWM 20-SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16C770-I/SO

• Core Size: 8-Bit
• Program Memory Size: 3.5KB (2K x 14)
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: I²C, SPI
• Number Of I /o: 15
• Program Memory Type: OTP
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 6x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-SOIC (7.5mm Width)
• Controller Family/series: PIC16C
• No. Of I/o's: 16
• Ram Memory Size: 256Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: ISPICR1 - ADAPTER IN-CIRCUIT PROGRAMMINGAC164028 - MODULE SKT PROMATEII 20SOIC/DIP309-1013 - ADAPTER 20-SOIC TO 20-DIP309-1012 - ADAPTER 20-SOIC TO 20-DIP
• Eeprom Size: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: PIC16C770I/SO

11.7
An A/D conversion can be started by the “special
event trigger” of the CCP module. This requires that
the CCP1M<3:0> bits be programmed as 1011b and
that the A/D module is enabled (ADON is set). When
the trigger occurs, the GO/DONE bit will be set on Q2
to start the A/D conversion and the Timer1 counter will
be reset to zero. Timer1 is RESET to automatically
repeat the A/D conversion cycle, with minimal soft-
ware overhead (moving the ADRESH and ADRESL to
the desired location). The appropriate analog input
channel must be selected before the “special event
trigger” sets the GO/DONE bit (starts a conversion
cycle).
If the A/D module is not enabled (ADON is cleared),
then the “special event trigger” will be ignored by the
A/D module, but will still RESET the Timer1 counter.
11.8
A device RESET forces all registers to their RESET
state. This forces the A/D module to be turned off, and
any conversion is aborted. The value that is in the
ADRESH and ADRESL registers are not modified.
The ADRESH and ADRESL registers will contain
unknown data after a Power-on Reset.
2002 Microchip Technology Inc.
Use of the ECCP Trigger
Effects of a RESET
11.9
Not all applications require a result with 12 bits of reso-
lution, but may instead require a faster conversion
time. The A/D module allows users to make the trade-
off of conversion speed to resolution. Regardless of
the resolution required, the acquisition time is the
same. To speed up the conversion, the A/D module
may be halted by clearing the GO/DONE bit after the
desired number of bits in the result have been con-
verted. Once the GO/DONE bit has been cleared, all
of the remaining A/D result bits are ‘0’. The equation
to determine the time before the GO/DONE bit can be
switched is as follows:
Since T
must use some method (a timer, software loop, etc.) to
determine when the A/D GO/DONE bit may be
cleared. Table 11-4 shows a comparison of time
required for a conversion with 4 bits of resolution, ver-
sus the normal 12-bit resolution conversion. The
example is for devices operating at 20 MHz. The A/D
clock is programmed for 32 T
EXAMPLE 11-4:
4-Bit Example:
12-Bit Example:
Where: N = number of bits of resolution required,
and 1T
Conversion time = (N+1)T
PIC16C717/770/771
Conversion Time = (N + 1) T
Conversion Time = (N + 1) T
AD
Faster Conversion - Lower
Resolution Trade-off
AD
is based from the device oscillator, the user
is the amplifier settling time.
4-BIT vs. 12-BIT
CONVERSION TIME
Example
= (4 + 1) T
= (5)(1.6 S)
= 8 S
= (12 + 1) T
= (13)(1.6 S)
= 20.8 S
OSC
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