Disabling Interrupts required ??

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

Hello All,

I am using the PIC 16F877 mcu, and the CCS PCM compiler.

I would like to know if it is necessary to call the disable_interrupts() function, before servicing an interrupt ?.

Also is it necessary to shut down all interrupt (by using the disable_interrupts() function) before writing to /reading the internal EEPROM using the write_eeprom() / read_eeprom() functions ??.

thanks
arun
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This message was ported from CCS's old forum
Original Post ID: 144516137

Sirio · Guest

:=Hello All,

Hi

:=I am using the PIC 16F877 mcu, and the CCS PCM compiler.
:=
:=I would like to know if it is necessary to call the disable_interrupts() function, before servicing an interrupt ?.

No.

:=Also is it necessary to shut down all interrupt (by using the disable_interrupts() function) before writing to /reading the internal EEPROM using the write_eeprom() / read_eeprom() functions ??.
:=

Don't think so.

:=thanks

np

:=arun
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This message was ported from CCS's old forum
Original Post ID: 144516148

Felix Althaus · Posted: Fri Jul 18, 2003 12:17 pm

Hi

From the PIC16F84A datasheet (but this is similar on the 16F87x):

"When an interrupt is responded to, the GIE bit is cleared to disable any further interrupt, [...]"

So, the PIC disables all interrupts for you. After the ISR, the chip turns the interrupts on again (exactly: the chip re-sets the GIE bit)

mfg
Felix
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This message was ported from CCS's old forum
Original Post ID: 144516157

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

:=:=Hello All,
:=
:=Hi
:=
:=:=I am using the PIC 16F877 mcu, and the CCS PCM compiler.
:=:=
:=:=I would like to know if it is necessary to call the disable_interrupts() function, before servicing an interrupt ?.
:=
:=No.
:=
:=:=Also is it necessary to shut down all interrupt (by using the disable_interrupts() function) before writing to /reading the internal EEPROM using the write_eeprom() / read_eeprom() functions ??.
:=:=
:=
:=Don't think so.
:=
:=:=thanks
:=
:=np
:=
:=:=arun

Hi,

thanks for the reply.

I find that the mcu sometimes writes garbage to the EEPROM. I felt that disabling interrupts was required, because in the datasheets it is recommended to turn off all interrupts, does the isr routine for any isr does this automatically ???

thanks
arun
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516169