[Icc-avr] Interrupt Help Please (Happy New Year)

[John Baraclough]

The processor is clearly in a different state when it goes to sleep from 
when it first starts up. At a guess, I would say you are leaving a port 
pin enabled and driving a low level out to a pull-up resistor (possibly 
more than one). Calculating the extra current; 112uA would be the 
current drawn through a 47k resistor from a 5V supply (or 30k and 3.3V).

What is the mechanism for turning off the RTC? The ideal way to do this 
is to use a resistive pull-up/pull-down to turn off the RTC and then 
overdrive it with the appropriate level from a port pin to turn it on. 
When the processor goes to sleep just tri-state all the port pins so 
there is no current drawn.

HTH

John

Andrew wrote:
> Hi john/anybody ,
>  
> I have a intresting/anoying problem. to recap. I have an AT90USB162. i 
> am basically trying to send the processor to sleep if Bit 1 on PORTD 
> is high and wake when the PIN goes low. The basically tells the 
> processor it has lost main power and is now running on a battery.
>  
> I have the code working well and i am getting 7.12uA when the 
> Processor is asleep.and my pin interrupt routine works and wakes the 
> processor if PORTD BIT1 is low and returns back to the 7.12uA when 
> PORTD BIT1 is high. The problem i have is when i pug the USB in. This 
> also has the same effect on PORTD BIT 1 as it now takes over powring 
> the system from the battery.
>  
> So as before if the USB connector is pugged in PORDT BIT 1 goes low 
> and the processor resumes from sleep. this also works and i can use 
> the USB port as a serial emulator using some atmel exmaple code. The 
> probelm comes when i unplug the USB connector. Which sends PORTD BIT 1 
> high and thus the processor goes to sleep but it only goes down to 
> 119uA not the 7.12uA i was getting before. I have checked and the 
> processor is asleep as the external oscillator is turnned off. So some 
> part of the USB must be still enabled. Can anybody suggest a solution: -
>  
> CODE
>  
> NOTE : -
>
> #define USB_CONNECTED (PIND & 0x01)
> #define BAT_CONNECTED (PIND & 0x02)
>
> are defined in a sepearte c file.
>
>  
> * *
>
> *void* sleep(*void*);
> *void* wake(*void*);
>
> //-----------------------------------------------------------------------------
> //
> // Function name : Sleep
> //
> // Returns : None
> //
> // Parameters : None
> //
> // Purpose : Send the processor into sleep mode (Low power)
> //
> //-----------------------------------------------------------------------------
> *void* sleep(*void*)
> {
>
> SPCR = 0x00;                    // Power Down the SPI
> UCSRB = 0x00;                // NOT FOUND THIS IN THe DATASHEET
>
> REGCR = 0x01;                 // Disable the USB Regulator
> RTC_POWER_OFF          // Turn the Power too the RTC OFF (PORTD4)
>
> EICRA = 0x08;                // Change INT1 Pin Interrupt to Falling 
> Edge (INT1)
>
> PRR1 = 0x81;                    // Turn Off the USB and USART using 
> the power reduction register
>
> SMCR = 0;                         // Clear SMCR Register
> SMCR = 0x05;                   // Configure Sleep Register for Deep Sleep
> asm(/"sleep"/);                     // Put Processor into Deep Sleep
>
> }
>
> //-----------------------------------------------------------------------------
> //
> // Function name : Wake
> //
> // Returns :
> //
> // Parameters :
> //
> // Purpose : Return from Sleep mode and restart devices
> //
> //-----------------------------------------------------------------------------
> *void* wake (*void*)
> {
> PRR1 = 0x00;                 // Restart the USB from Power Reduction Mode
> EICRA = 0x0C;              // Change the Battery on pin to interrupt 
> on rising edge (INT1)
> RTC_POWER_ON        // Turn the RTC Power Supply back on (PORTD4)
>
> UCSRB = 0x98;               // HAVE NO IDEA WHAT THIS REGISTRY IS FOR
> SPCR = 0x5C;                 // Restart the SPI
> Usb_enable_regulator();    // Enable the USB regulator
> }
>
> //-----------------------------------------------------------------------------
> // Main Program Loop
> //-----------------------------------------------------------------------------
> *void* main(*void*)
> {
> init_devices();                 // Initilise all the devices
>
> Usb_enable_regulator(); // Enable the USB Regulator
> usb_scheduler_init();       // Set up the USB Scheduler
>
> *while* (1)
> {
>
> *if*(USB_CONNECTED) // If the USB Connected Pin is High
> {
> usb_scheduler_tasks();    // Schedule the USB tasks
> }
>
> *if*(BAT_CONNECTED)  // If the Battery Connected Pin is high
> {
> sleep(); // Call the Sleep function
> NOP(); // Small Delay
> NOP(); // Small Delay
> wake(); // Wake from Sleep and restart USB and SPI
>
> }
>
> }
> }
>
>  Andy
> ------------------------------------------------------------------------
>
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