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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(500);
- battery_led(LED_OFF); _delay_ms(500);
- battery_led(LED_ON); _delay_ms(500);
- battery_led(LED_OFF); _delay_ms(500);
- // 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);
- ADCSRA |= (1<<ADEN);
-
- // 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);
-
- // discard first result
- ADCSRA |= (1<<ADSC);
- while (ADCSRA & (1<<ADSC)) ;
- bat = ADC;
-
- // discard second result
- ADCSRA |= (1<<ADSC);
- while (ADCSRA & (1<<ADSC)) ;
- bat = ADC;
-
- 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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