fixed ADC on attiny1634 and related builds

2 files changed, 132 insertions, 37 deletions

diff --git a/arch/attiny1634.c b/arch/attiny1634.c
index 0737a81..e29d1c3 100644
--- a/arch/attiny1634.c
+++ b/arch/attiny1634.c
@@ -7,14 +7,26 @@
 
 ////////// clock speed / delay stuff //////////
 
+inline void mcu_clock_speed() {
+    // TODO?
+    // (or not; clock speed is set by the fuses)
+    // attiny1634 datasheet 6.5
+    // CLKSR = [OSCRDY, CSTR, CKOUT_IO, SUT, CKSEL3/2/1/0]
+    // default 8MHz calibrated internal clock: SUT=0, CKSEL=0b0010
+    #if 0
+    cli();
+    CCP = 0xD8;
+    CLKSR = 0b01000010;
+    CCP = 0xD8;
+    CLKPR = 0;  // CLK / 1 = full speed, 8 MHz
+    sei();
+    #endif
+}
+
 ///// clock dividers
-// make it a NOP for now
-// FIXME
-//#define clock_prescale_set(x) ((void)0)
-//#define clock_prescale_set(n) {cli(); CCP = 0xD8; CLKPR = n; sei();}
-//#define clock_prescale_set(n) {cli(); CCP = 0xD8; CLKPR = n; sei();}
 inline void clock_prescale_set(uint8_t n) {
     cli();
+    // _PROTECTED_WRITE(CLKPR, n);
     CCP = 0xD8;
     CLKPR = n;
     sei();
@@ -26,15 +38,33 @@ inline void clock_prescale_set(uint8_t n) {
 ////////// ADC voltage / temperature //////////
 
 inline void mcu_set_admux_therm() {
+    // put the ADC in temperature mode
+    // DS table 19-3, 19-4, internal sensor / 1.1V ref
+    // [refs1, refs0, refen, adc0en, mux3, mux2, mux1, mux0]
+    // refs=0b10 : internal 1.1V ref
+    // mux=0b1110 : internal temperature sensor
+    //#define ADMUX_THERM 0b10001110
     ADMUX = ADMUX_THERM;
+    // other stuff is already set, so no need to re-set it
 }
 
 inline void mcu_set_admux_voltage() {
+    // put the ADC in battery voltage measurement mode
+    // TODO: avr datasheet references
     #ifdef USE_VOLTAGE_DIVIDER  // 1.1V / pin7
         ADMUX = ADMUX_VOLTAGE_DIVIDER;
+        // disable digital input on divider pin to reduce power consumption
+        // TODO: this should be in hwdef init, not here
+        VOLTAGE_ADC_DIDR |= (1 << VOLTAGE_ADC);
     #else  // VCC / 1.1V reference
         ADMUX = ADMUX_VCC;
+        // disable digital input on VCC pin to reduce power consumption
+        //VOLTAGE_ADC_DIDR |= (1 << VOLTAGE_ADC);  // FIXME: unsure how to handle for VCC pin
     #endif
+    //ACSRA |= (1 << ACD);  // turn off analog comparator to save power
+    // ADCSRB: [VDEN, VDPD, -, -, ADLAR, ADTS2, ADTS1, ADTS0]
+    ADCSRB = (1 << ADLAR);  // left-adjust, free-running
+    //ADCSRB = 0;  // right-adjust, free-running
 }
 
 inline void mcu_adc_sleep_mode() {
@@ -42,31 +72,82 @@ inline void mcu_adc_sleep_mode() {
 }
 
 inline void mcu_adc_start_measurement() {
-    ADCSRA |= (1 << ADSC) | (1 << ADIE);
-}
-
-inline void mcu_adc_on() {
-    hwdef_set_admux_voltage();
-    #ifdef USE_VOLTAGE_DIVIDER
-        // disable digital input on divider pin to reduce power consumption
-        VOLTAGE_ADC_DIDR |= (1 << VOLTAGE_ADC);
-    #else
-        // disable digital input on VCC pin to reduce power consumption
-        //VOLTAGE_ADC_DIDR |= (1 << VOLTAGE_ADC);  // FIXME: unsure how to handle for VCC pin
-    #endif
-    //ACSRA |= (1 << ACD);  // turn off analog comparator to save power
-    ADCSRB |= (1 << ADLAR);  // left-adjust flag is here instead of ADMUX
-    // enable, start, auto-retrigger, prescale
-    ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADATE) | ADC_PRSCL;
+    // [ADEN, ADSC, ADATE, adif, ADIE, ADPS2, ADPS1, ADPS0]
+    ADCSRA = (1 << ADEN)   // enable
+           | (1 << ADSC)   // start
+           | (1 << ADATE)  // auto-retrigger
+           | (1 << ADIE)   // interrupt enable
+           | ADC_PRSCL;    // prescale
 }
 
 inline void mcu_adc_off() {
     ADCSRA &= ~(1<<ADEN); //ADC off
 }
 
+// left-adjusted mode:
 inline uint16_t mcu_adc_result() { return ADC; }
+//inline uint16_t mcu_adc_result() { return (uint16_t)(ADCL | (ADCH << 8)); }
+// right-adjusted mode:
+/*
+inline uint16_t mcu_adc_result() {
+    uint16_t result = (ADCL | (ADCH << 8)) << 6;
+    return result;
+}
+*/
+
+inline uint8_t mcu_vdd_raw2cooked(uint16_t measurement) {
+    // In : 65535 * 1.1 / Vbat
+    // Out: uint8_t: Vbat * 40
+    // 1.1 = ADC Vref
+    #if 0
+    // 1024 = how much ADC resolution we're using (10 bits)
+    // (12 bits available, but it costs an extra 84 bytes of ROM to calculate)
+    uint8_t vbat40 = (uint16_t)(40 * 1.1 * 1024) / (measurement >> 6);
+    #else
+    // ... spend the extra 84 bytes of ROM for better precision
+    // 4096 = how much ADC resolution we're using (12 bits)
+    uint8_t vbat40 = (uint32_t)(40 * 1.1 * 4096) / (measurement >> 4);
+    #endif
+    return vbat40;
+}
 
-inline uint8_t mcu_adc_lsb() { return (ADCL >> 6) + (ADCH << 2); }
+
+#ifdef USE_VOLTAGE_DIVIDER
+inline uint8_t mcu_vdivider_raw2cooked(uint16_t measurement) {
+    // In : 4095 * Vdiv / 1.1V
+    // Out: uint8_t: Vbat * 40
+    // Vdiv = Vbat / 4.3  (typically)
+    // 1.1 = ADC Vref
+    const uint16_t adc_per_volt =
+            (((uint16_t)ADC_44 << 4) - ((uint16_t)ADC_22 << 4))
+            / (4 * (44-22));
+    uint8_t result = measurement / adc_per_volt;
+    return result;
+}
+#endif
+
+inline uint16_t mcu_temp_raw2cooked(uint16_t measurement) {
+    // convert raw ADC values to calibrated temperature
+    // In: ADC raw temperature (16-bit, or left-aligned)
+    // Out: Kelvin << 6
+    // Precision: 1/64th Kelvin (but noisy)
+    // attiny1634 datasheet section 19.12
+    // nothing to do; input value is already "cooked"
+    return measurement;
+}
+
+inline uint8_t mcu_adc_lsb() {
+    // left-adjusted mode:
+    return (ADCL >> 6) + (ADCH << 2);
+    // right-adjusted mode:
+    // datasheet 19.13.3.2:
+    // "When ADCL is read, the ADC Data Register is not updated
+    //  until ADCH is read. ... ADCL must be read first, then ADCH."
+    // So... gotta read it even if not needed?
+    // (the value doesn't matter here, the lower bits are only used
+    //  for generating some random seed data)
+    //return ADCL + ADCH;
+}
 
 
 ////////// WDT //////////
@@ -85,6 +166,7 @@ inline void mcu_wdt_stop() {
     cli();                // needed because CCP, below
     wdt_reset();          // Reset the WDT
     MCUSR &= ~(1<<WDRF);  // clear watchdog reset flag
+    // _PROTECTED_WRITE(WDTCSR, 0);
     CCP = 0xD8;           // enable config changes
     WDTCSR = 0;           // disable and clear all WDT settings
     sei();
@@ -113,6 +195,7 @@ inline void mcu_pcint_off() {
 void reboot() {
     // put the WDT in hard reset mode, then trigger it
     cli();
+    // _PROTECTED_WRITE(WDTCSR, 0b10001000);
     // allow protected configuration changes for next 4 clock cycles
     CCP = 0xD8;  // magic number
     // reset (WDIF + WDE), no WDIE, fastest (16ms) timing (0000)
@@ -126,6 +209,6 @@ void reboot() {
 inline void prevent_reboot_loop() {
     // prevent WDT from rebooting MCU again
     MCUSR &= ~(1<<WDRF);  // reset status flag
-    wdt_disable();
+    wdt_disable();  // from avr/wdt.h
 }
 
diff --git a/arch/attiny1634.h b/arch/attiny1634.h
index fb89fa8..559d04e 100644
--- a/arch/attiny1634.h
+++ b/arch/attiny1634.h
@@ -13,20 +13,25 @@
 #define BOGOMIPS  (F_CPU/4000)
 #define DELAY_ZERO_TIME  1020
 
+inline void mcu_clock_speed();
+
 ///// clock dividers
 inline void clock_prescale_set(uint8_t n);
 
+// TODO? allow hwdef to define a base clock speed,
+//       and adjust these values accordingly
 typedef enum
 {
-    clock_div_1 = 0,
-    clock_div_2 = 1,
-    clock_div_4 = 2,
-    clock_div_8 = 3,
-    clock_div_16 = 4,
-    clock_div_32 = 5,
-    clock_div_64 = 6,
-    clock_div_128 = 7,
-    clock_div_256 = 8
+    // datasheet 6.5.2, CLKPR - Clock Prescale Register
+    clock_div_1   = 0,  // 8 MHz
+    clock_div_2   = 1,  // 4 MHz
+    clock_div_4   = 2,  // 2 MHz
+    clock_div_8   = 3,  // 1 MHz
+    clock_div_16  = 4,  // 500 kHz
+    clock_div_32  = 5,  // 250 kHz
+    clock_div_64  = 6,  // 125 kHz
+    clock_div_128 = 7,  // 62.5 kHz
+    clock_div_256 = 8,  // 31.75 kHz
 } clock_div_t;
 
 
@@ -39,11 +44,11 @@ typedef enum
 #define ADMUX_VCC 0b00001101
 // (1 << V_REF) | (THERM_CHANNEL)
 // DS table 19-3, 19-4, internal sensor / 1.1V ref
+// [refs1, refs0, refen, adc0en, mux3, mux2, mux1, mux0]
+// refs=0b10 : internal 1.1V ref
+// mux=0b1110 : internal temperature sensor
 #define ADMUX_THERM 0b10001110
 
-
-
-
 #define hwdef_set_admux_therm  mcu_set_admux_therm
 inline void mcu_set_admux_therm();
 
@@ -54,8 +59,6 @@ inline void mcu_adc_sleep_mode();
 
 inline void mcu_adc_start_measurement();
 
-inline void mcu_adc_on();
-
 inline void mcu_adc_off();
 
 // NOP because interrupt flag clears itself
@@ -63,6 +66,15 @@ inline void mcu_adc_off();
 
 inline uint16_t mcu_adc_result();
 
+// return Volts * 40, range 0 to 6.375V
+#define voltage_raw2cooked  mcu_vdd_raw2cooked
+inline uint8_t mcu_vdd_raw2cooked(uint16_t measurement);
+inline uint8_t mcu_vdivider_raw2cooked(uint16_t measurement);
+
+// return (temp in Kelvin << 6)
+#define temp_raw2cooked  mcu_temp_raw2cooked
+inline uint16_t mcu_temp_raw2cooked(uint16_t measurement);
+
 inline uint8_t mcu_adc_lsb();