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-rw-r--r--keyboard/hhkb/rn42/battery.c130
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diff --git a/keyboard/hhkb/rn42/battery.c b/keyboard/hhkb/rn42/battery.c
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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);
+ // 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;
+ }
+}