1 files changed, 130 insertions, 0 deletions

diff --git a/keyboards/hhkb/rn42/battery.c b/keyboards/hhkb/rn42/battery.c
new file mode 100644
index 000000000..c0c82bb80
--- /dev/null
+++ b/keyboards/hhkb/rn42/battery.c
@@ -0,0 +1,130 @@
+#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;
+    }
+}