PIC16F877A-I/PT Microchip Technology Inc., PIC16F877A-I/PT Datasheet - Page 118

• Manufacturer Part Number: PIC16F877A-I/PT
• Description: 44 PIN, 7 KB FLASH, 368 RAM, 33 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F877A-I/PT

• A/d Inputs: 8-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 33
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 44-pin TQFP
• Programmable Memory: 14K Bytes
• Ram Size: 368 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC16F87X
11.4
Clearing the GO/DONE bit during a conversion will
abort the current conversion. The A/D result register
pair will NOT be updated with the partially completed
A/D conversion sample. That is, the ADRESH:ADRESL
registers will continue to contain the value of the last
completed conversion (or the last value written to the
ADRESH:ADRESL registers). After the A/D conversion
is aborted, a 2T
FIGURE 11-3:
11.4.1
The ADRESH:ADRESL register pair is the location
where the 10-bit A/D result is loaded at the completion
of the A/D conversion. This register pair is 16-bits wide.
The A/D module gives the flexibility to left or right justify
the 10-bit result in the 16-bit result register. The A/D
FIGURE 11-4:
DS30292C-page 116
A/D Conversions
A/D RESULT REGISTERS
T
CY
Set GO bit
Holding capacitor is disconnected from analog input (typically 100 ns)
7
to T
AD
0000 00
ADRESH
AD
wait is required before the next
Conversion starts
A/D CONVERSION T
A/D RESULT JUSTIFICATION
T
AD
Right Justified
1
2 1 0 7
ADFM = 1
T
AD
b9
2
10-bit Result
T
ADRESL
AD
b8
3
T
AD
b7
AD
4
0
CYCLES
T
AD
b6
10-bit Result
5
T
AD
b5
6
acquisition is started. After this 2T
on the selected channel is automatically started. The
GO/DONE bit can then be set to start the conversion.
In Figure 11-3, after the GO bit is set, the first time seg-
ment has a minimum of T
Format Select bit (ADFM) controls this justification.
Figure 11-4 shows the operation of the A/D result justi-
fication. The extra bits are loaded with ’0’s’. When an
A/D result will not overwrite these locations (A/D dis-
able), these registers may be used as two general
purpose 8-bit registers.
ADRES is loaded
GO bit is cleared
ADIF bit is set
Holding capacitor is connected to analog input
T
AD
b4
Note:
7
7
T
AD
b3
ADRESH
8
The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
10-bit Result
T
AD
b2
ADFM = 0
9
Left Justified
T
0 7 6 5
AD
b1
10 T
CY
ADRESL
2001 Microchip Technology Inc.
and a maximum of T
AD
b0
0000 00
11
AD
0
wait, acquisition
AD
.