[Gumstix-users] Additional interrupt problem in i2c-io

[VaibhavGhadiok <vai...@gm...>]

hi everyone

I have added two additional interrupts to i2c-io. I am having a problem with
one of them. On the robostix, I receive messages from the gumstix to update
throttle values. I wanted to have an emergency stop system. On detecting an
interrupt on INT4 the robostix would disable the interrupts that are used to
receive messages from the gumstix via i2c. And will set the throttle value
to a  lower value. (See INT4_vect interrupt routine below). Is there a
better method to do this?

When only the robostix program is running (gumstix program not running), the
interrupt on INT 4 is detected and the throttle value updated to a lower
value as seen on the oscilloscope. This should disable interrupts 0-3 and
this should disable receiving messages from the gumstix. However, this is
not the case.  

Problem 1: Even after entering the INT4_vect routine and disabling the
interrupts, I am again able to receive I2C messages if I start a gumstix
program. 

Problem 2: While running the gumstix program, the code doesn't interrupt.
After I stop the gumstix program, I am again able to interrupt the robostix
program.

Is this because of the use of the SIGNAL routine (for receiving commands
from the gumstix for i2c) instead of ISR. I believe SIGNAL doesn't allow
itself to be interrupted.


    //Emergency Stop Setup
    DDRE  &= 0xEF; //Make Interrupt 4 as input
    EICRB |= 0x03; //Interrupt on rising edge
    EIMSK |= (1 << INT4); //Enable Interrupt 4, PWM 3B

sei(); //Enable all INterrupts

while (1)
{...}

//
**************************************************************************
// PWM Interrupt
//This interrupt works completely fine. Have it here for completeness
ISR(TIMER1_COMPA_vect)
{
	//sei();
	ICR1 = pulse_usec[counter++];
	if (counter == 14)
	counter = 0;
}

//***************************************************************************

// Emergency Stop Interrupt PWM 3B
//This is the routine with the problem
ISR(INT4_vect)
{
	EIMSK &= 0xF0; //Disbale Interrupts 0,1, 2, 3, all the I2C and TX, RX
//Which are the interrupts that I need to disable in order to stop receiving
messages from the gumstix
	
pulse_usec[4] = 1025; //Change the throtle value;

}

Thanks

Vaibhav
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