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#include <avr/io.h>
#include <util/delay.h>
#include "battery.h"
/*
* Battery
*/
void battery_init(void)
{
// blink
battery_led(LED_ON); _delay_ms(100);
battery_led(LED_OFF); _delay_ms(100);
battery_led(LED_ON); _delay_ms(100);
battery_led(LED_OFF); _delay_ms(100);
// LED indicates charger status
battery_led(LED_CHARGER);
// ADC setting for voltage monitor
// Ref:2.56V band-gap, Input:ADC0(PF0), Prescale:128(16MHz/128=125KHz)
ADMUX = (1<<REFS1) | (1<<REFS0);
ADCSRA = (1<<ADPS2) | (1<<ADPS1) | (1<<ADPS0);
// digital input buffer disable(24.9.5)
DIDR0 = (1<<ADC0D) | (1<<ADC4D) | (1<<ADC7D);
DIDR1 = (1<<AIN0D);
DIDR2 = (1<<ADC8D) | (1<<ADC9D) | (1<<ADC11D) | (1<<ADC12D) | (1<<ADC13D);
// ADC disable voltate divider(PF4)
DDRF |= (1<<4);
PORTF &= ~(1<<4);
}
// Indicator for battery
void battery_led(battery_led_t val)
{
if (val == LED_TOGGLE) {
// Toggle LED
DDRF |= (1<<5);
PINF |= (1<<5);
} else if (val == LED_ON) {
// On overriding charger status
DDRF |= (1<<5);
PORTF &= ~(1<<5);
} else if (val == LED_OFF) {
// Off overriding charger status
DDRF |= (1<<5);
PORTF |= (1<<5);
} else {
// Display charger status
DDRF &= ~(1<<5);
PORTF &= ~(1<<5);
}
}
bool battery_charging(void)
{
if (!(USBSTA&(1<<VBUS))) return false;
// Charger Status:
// MCP73831 MCP73832 LTC4054 Status
// Hi-Z Hi-Z Hi-Z Shutdown/No Battery
// Low Low Low Charging
// Hi Hi-Z Hi-Z Charged
// preserve last register status
uint8_t ddrf_prev = DDRF;
uint8_t portf_prev = PORTF;
// Input with pullup
DDRF &= ~(1<<5);
PORTF |= (1<<5);
_delay_ms(1);
bool charging = PINF&(1<<5) ? false : true;
// restore last register status
DDRF = (DDRF&~(1<<5)) | (ddrf_prev&(1<<5));
PORTF = (PORTF&~(1<<5)) | (portf_prev&(1<<5));
// TODO: With MCP73831 this can not get stable status when charging.
// LED is powered from PSEL line(USB or Lipo)
// due to weak low output of STAT pin?
// due to pull-up'd via resitor and LED?
return charging;
}
// Returns voltage in mV
uint16_t battery_voltage(void)
{
// ADC disable voltate divider(PF4)
DDRF |= (1<<4);
PORTF |= (1<<4);
volatile uint16_t bat;
ADCSRA |= (1<<ADEN);
_delay_ms(1); // wait for charging S/H capacitance
ADCSRA |= (1<<ADSC);
while (ADCSRA & (1<<ADSC)) ;
bat = ADC;
ADCSRA &= ~(1<<ADEN);
// ADC disable voltate divider(PF4)
DDRF |= (1<<4);
PORTF &= ~(1<<4);
return (bat - BATTERY_ADC_OFFSET) * BATTERY_ADC_RESOLUTION;
}
static bool low_voltage(void) {
static bool low = false;
uint16_t v = battery_voltage();
if (v < BATTERY_VOLTAGE_LOW_LIMIT) {
low = true;
} else if (v > BATTERY_VOLTAGE_LOW_RECOVERY) {
low = false;
}
return low;
}
battery_status_t battery_status(void)
{
if (USBSTA&(1<<VBUS)) {
/* powered */
return battery_charging() ? CHARGING : FULL_CHARGED;
} else {
/* not powered */
return low_voltage() ? LOW_VOLTAGE : DISCHARGING;
}
}
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