AVR Freaks

Hi AVR experts!

The setup:

I use a device that performs a man-in-the-middle attack on the CAN bus in my electric car. The board allow my car to use a newer battery that it came with. It is extremely vital for the function of the whole car, without it the car shuts off and goes into limp mode.

Here is the hardware: https://www.tindie.com/products/...

It is running an XMEGA32C4 along with some CAN controllers that interface to it via SPI

The issue:

The board uses a lot of power even when the car is off. It consumes ca 35mA. This kills the 12V battery if you don't drive the car for 5-7days.

My question. Is it possible to even use some sleep settings here to save power? The board need to be responsive and trigger immediately when a CAN message comes, since without the board, CAN messages wont be transmitted between the battery and the car.

Here is what the HW setup looks like, don't know if this helps.

void hw_init(void){
	uint8_t caninit;

	/* Start the 32MHz internal RC oscillator and start the DFLL to increase it to 48MHz using the USB SOF as a reference */
	XMEGACLK_StartInternalOscillator(CLOCK_SRC_INT_RC32MHZ);
	XMEGACLK_StartDFLL(CLOCK_SRC_INT_RC32MHZ, DFLL_REF_INT_USBSOF, 48000000);		
	
	//turn off everything we don' t use
	PR.PRGEN		= PR_AES_bm | PR_RTC_bm | PR_DMA_bm;
	PR.PRPA			= PR_ADC_bm | PR_AC_bm;
	PR.PRPC			= PR_TWI_bm | PR_USART0_bm | PR_HIRES_bm;
	PR.PRPD			= PR_TWI_bm | PR_USART0_bm | PR_TC0_bm | PR_TC1_bm;
	PR.PRPE			= PR_TWI_bm | PR_USART0_bm;
	
	//blink output
	PORTB.DIRSET	= 3;
	
	//start 16MHz crystal and PLL it up to 48MHz
	OSC.XOSCCTRL	= OSC_FRQRANGE_12TO16_gc |		//16MHz crystal
	OSC_XOSCSEL_XTAL_16KCLK_gc;						//16kclk startup
	OSC.CTRL	   |= OSC_XOSCEN_bm;				//enable crystal
	while(!(OSC.STATUS & OSC_XOSCRDY_bm));			//wait until ready
	OSC.PLLCTRL		= OSC_PLLSRC_XOSC_gc | 2;		//XTAL->PLL, 2x multiplier (32MHz)
	OSC.CTRL	   |= OSC_PLLEN_bm;					//start PLL
	while (!(OSC.STATUS & OSC_PLLRDY_bm));			//wait until ready
	CCP				= CCP_IOREG_gc;					//allow changing CLK.CTRL
	CLK.CTRL		= CLK_SCLKSEL_PLL_gc;			//use PLL output as system clock	
	
	//output 16MHz clock to MCP25625 chips (PE0)
	//next iteration: put this on some other port, pin 4 or 7, so we can use the event system
	TCE0.CTRLA		= TC0_CLKSEL_DIV1_gc;						//clkper/1
	TCE0.CTRLB		= TC0_CCAEN_bm | TC0_WGMODE_SINGLESLOPE_bm;	//enable CCA, single-slope PWM
	TCE0.CCA		= 1;										//compare value
	TCE0.PER		= 1;										//period of 1, generates 24MHz output
	
	PORTE.DIRSET	= PIN0_bm;									//set CLKOUT pin to output
	
	//setup CAN pin interrupts
	PORTC.INTCTRL	= PORT_INT0LVL_HI_gc;
	PORTD.INTCTRL	= PORT_INT0LVL_HI_gc | PORT_INT1LVL_HI_gc;	
	
	PORTD.INT0MASK	= PIN0_bm;						//PORTD0 has can1 interrupt
	PORTD.PIN0CTRL	= PORT_OPC_PULLUP_gc | PORT_ISC_LEVEL_gc;
	
	PORTD.INT1MASK	= PIN5_bm;						//PORTD5 has can2 interrupt
	PORTD.PIN5CTRL	= PORT_OPC_PULLUP_gc | PORT_ISC_LEVEL_gc;
	
	#ifndef DISABLE_CAN3
	PORTC.INT0MASK	= PIN2_bm;						//PORTC2 has can3 interrupt
	PORTC.PIN0CTRL	= PORT_OPC_PULLUP_gc | PORT_ISC_LEVEL_gc;
	#endif
	
	//buffer checking interrupt
	TCC1.CTRLA		= TC0_CLKSEL_DIV1_gc;			//48M/1/4800 ~ 100usec
	TCC1.PER		= 4800;
	TCC1.INTCTRLA	= TC0_OVFINTLVL_HI_gc;			//same priority as can interrupts
	
	//we want to optimize performance, so we're going to time stuff
	//48MHz/48=1us timer, which we just freerun and reset whenever we want to start timing something
	//frame time timer
	TCC0.CTRLA		= TC0_CLKSEL_DIV1_gc;
	TCC0.PER		= 48000;						//48MHz/48000=1ms
	TCC0.INTCTRLA	= TC0_OVFINTLVL_HI_gc;			//interrupt on overflow
	
	PORTB.OUTCLR	= (1 << 0);
	
	can_system_init:
			
	//Init SPI and CAN interface:
	if(RST.STATUS & RST_WDRF_bm){ //if we come from a watchdog reset, we don't need to setup CAN
		caninit = can_init(MCP_OPMOD_NORMAL, 1); //on second thought, we do
	} else {
		caninit = can_init(MCP_OPMOD_NORMAL, 1);
	}
	
	if(caninit){		
		PORTB.OUTSET |= (1 << 0);					//green LED
	} else {		
		PORTB.OUTSET |= (1 << 1);					//red LED
		_delay_ms(10);
		goto can_system_init;
	}
	
	//Set and enable interrupts with round-robin
	XMEGACLK_CCP_Write((void * ) &PMIC.CTRL, PMIC_RREN_bm | PMIC_LOLVLEN_bm | PMIC_HILVLEN_bm);//PMIC.CTRL = PMIC_LOLVLEN_bm | PMIC_MEDLVLEN_bm| PMIC_HILVLEN_bm;
	
	USB_Init(USB_OPT_RC32MCLKSRC | USB_OPT_BUSEVENT_PRILOW);
	CDC_Device_CreateStream(&VirtualSerial_CDC_Interface, &USBSerialStream);
	
	wdt_enable(WDTO_15MS);
	
	sei();
}

Thank you for looking :)