keyboard/hhkb_rn42/rn42/battery.c

   1 #include <avr/io.h>
   2 #include <util/delay.h>
   3 #include "battery.h"
   4
   5
   6 /*
   7  * Battery
   8  */
   9 void battery_init(void)
  10 {
  11     // blink
  12     battery_led(LED_ON);  _delay_ms(500);
  13     battery_led(LED_OFF); _delay_ms(500);
  14     battery_led(LED_ON);  _delay_ms(500);
  15     battery_led(LED_OFF); _delay_ms(500);
  16     // LED indicates charger status
  17     battery_led(LED_CHARGER);
  18
  19     // ADC setting for voltage monitor
  20     // Ref:2.56V band-gap, Input:ADC0(PF0), Prescale:128(16MHz/128=125KHz)
  21     ADMUX = (1<<REFS1) | (1<<REFS0);
  22     ADCSRA = (1<<ADPS2) | (1<<ADPS1) | (1<<ADPS0);
  23     ADCSRA |= (1<<ADEN);
  24     // digital input buffer disable(24.9.5)
  25     DIDR0 = (1<<ADC0D) | (1<<ADC4D) | (1<<ADC5D) | (1<<ADC7D);
  26     DIDR1 = (1<<AIN0D);
  27     DIDR2 = (1<<ADC8D) | (1<<ADC9D) | (1<<ADC11D) | (1<<ADC12D) | (1<<ADC13D);
  28
  29     // ADC disable voltate divider(PF4)
  30     DDRF  |=  (1<<4);
  31     PORTF &= ~(1<<4);
  32 }
  33
  34 // Indicator for battery
  35 void battery_led(battery_led_t val)
  36 {
  37     if (val == LED_TOGGLE) {
  38         // Toggle LED
  39         DDRF  |=  (1<<5);
  40         PINF  |=  (1<<5);
  41     } else if (val == LED_ON) {
  42         // On overriding charger status
  43         DDRF  |=  (1<<5);
  44         PORTF &= ~(1<<5);
  45     } else if (val == LED_OFF) {
  46         // Off overriding charger status
  47         DDRF  |=  (1<<5);
  48         PORTF |=  (1<<5);
  49     } else {
  50         // Display charger status
  51         DDRF  &= ~(1<<5);
  52         PORTF &= ~(1<<5);
  53     }
  54 }
  55
  56 bool battery_charging(void)
  57 {
  58     if (!(USBSTA&(1<<VBUS))) return false;
  59
  60     // Charger Status:
  61     //   MCP73831   MCP73832   LTC4054  Status
  62     //   Hi-Z       Hi-Z       Hi-Z     Shutdown/No Battery
  63     //   Low        Low        Low      Charging
  64     //   Hi         Hi-Z       Hi-Z     Charged
  65
  66     // preserve last register status
  67     uint8_t ddrf_prev  = DDRF;
  68     uint8_t portf_prev = PORTF;
  69
  70     // Input with pullup
  71     DDRF  &= ~(1<<5);
  72     PORTF |=  (1<<5);
  73     _delay_ms(1);
  74     bool charging = PINF&(1<<5) ? false : true;
  75
  76     // restore last register status
  77     DDRF  = (DDRF&~(1<<5))  | (ddrf_prev&(1<<5));
  78     PORTF = (PORTF&~(1<<5)) | (portf_prev&(1<<5));
  79
  80     // TODO: With MCP73831 this can not get stable status when charging.
  81     // LED is powered from PSEL line(USB or Lipo)
  82     // due to weak low output of STAT pin?
  83     // due to pull-up'd via resitor and LED?
  84     return charging;
  85 }
  86
  87 // Returns voltage in mV
  88 uint16_t battery_voltage(void)
  89 {
  90     // ADC disable voltate divider(PF4)
  91     DDRF  |=  (1<<4);
  92     PORTF |=  (1<<4);
  93
  94     volatile uint16_t bat;
  95     //ADCSRA |= (1<<ADEN);
  96
  97     // discard first result
  98     ADCSRA |= (1<<ADSC);
  99     while (ADCSRA & (1<<ADSC)) ;
 100     bat = ADC;
 101
 102     // discard second result
 103     ADCSRA |= (1<<ADSC);
 104     while (ADCSRA & (1<<ADSC)) ;
 105     bat = ADC;
 106
 107     ADCSRA |= (1<<ADSC);
 108     while (ADCSRA & (1<<ADSC)) ;
 109     bat = ADC;
 110
 111     //ADCSRA &= ~(1<<ADEN);
 112
 113     // ADC disable voltate divider(PF4)
 114     DDRF  |=  (1<<4);
 115     PORTF &= ~(1<<4);
 116
 117     return (bat - BATTERY_ADC_OFFSET) * BATTERY_ADC_RESOLUTION;
 118 }
 119
 120 static bool low_voltage(void) {
 121     static bool low = false;
 122     uint16_t v = battery_voltage();
 123     if (v < BATTERY_VOLTAGE_LOW_LIMIT) {
 124         low = true;
 125     } else if (v > BATTERY_VOLTAGE_LOW_RECOVERY) {
 126         low = false;
 127     }
 128     return low;
 129 }
 130
 131 battery_status_t battery_status(void)
 132 {
 133     if (USBSTA&(1<<VBUS)) {
 134         /* powered */
 135         return battery_charging() ? CHARGING : FULL_CHARGED;
 136     } else {
 137         /* not powered */
 138         return low_voltage() ? LOW_VOLTAGE : DISCHARGING;
 139     }
 140 }