PIC16F913-I/SP Microchip Technology Inc., PIC16F913-I/SP Datasheet - Page 200

• Manufacturer Part Number: PIC16F913-I/SP
• Description: 28 PIN, 7 KB FLASH, 352 RAM, 25 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F913-I/SP

• A/d Inputs: 5-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 25
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 7K Bytes
• Ram Size: 256 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

PIC16F917/916/914/913
16.5
During an interrupt, only the return PC value is saved
on the stack. Typically, users may wish to save key
registers during an interrupt (e.g., W and Status
registers). This must be implemented in software.
Since the lower 16 bytes of all banks are common in the
PIC16F917/916/914/913 (see Figure 2-3), temporary
holding registers, W_TEMP and STATUS_TEMP,
should be placed in here. These 16 locations do not
require banking and therefore, make it easier to context
save and restore. The same code shown in
Example 16-1 can be used to:
• Store the W register
• Store the Status register
• Execute the ISR code
• Restore the Status (and Bank Select Bit register)
• Restore the W register
EXAMPLE 16-1:
DS41250E-page 198
Note:
MOVWF
SWAPF
CLRF
MOVWF
:
:(ISR)
:
SWAPF
MOVWF
SWAPF
SWAPF
Context Saving During Interrupts
The PIC16F917/916/914/913
does not require saving the PCLATH.
However, if computed GOTO’s are used in
the ISR and the main code, the PCLATH
must be saved and restored in the ISR.
W_TEMP
STATUS,W
STATUS
STATUS_TEMP
STATUS_TEMP,W
STATUS
W_TEMP,F
W_TEMP,W
SAVING STATUS AND W REGISTERS IN RAM
;Copy W to TEMP register
;Swap status to be saved into W
;bank 0, regardless of current bank, Clears IRP,RP1,RP0
;Save status to bank zero STATUS_TEMP register
;Insert user code here
;Swap STATUS_TEMP register into W
;(sets bank to original state)
;Move W into Status register
;Swap W_TEMP
;Swap W_TEMP into W
normally
Preliminary
© 2005 Microchip Technology Inc.