From dbe0aaf636ccb78a3cc1281b6a1ea6c662af6756 Mon Sep 17 00:00:00 2001
From: Gabriel Hart
Date: Fri, 18 Dec 2020 15:23:31 -0600
Subject: Add AVR 1-Series and t1616 board and scripts

---
 spaghetti-monster/fsm-adc.c | 53 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

(limited to 'spaghetti-monster/fsm-adc.c')

diff --git a/spaghetti-monster/fsm-adc.c b/spaghetti-monster/fsm-adc.c
index 71ecf65..2818731 100644
--- a/spaghetti-monster/fsm-adc.c
+++ b/spaghetti-monster/fsm-adc.c
@@ -37,6 +37,9 @@ static inline void set_admux_therm() {
     #elif (ATTINY == 841)  // FIXME: not tested
         ADMUXA = ADMUXA_THERM;
         ADMUXB = ADMUXB_THERM;
+    #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc
+        ADC0.MUXPOS = ADC_MUXPOS_TEMPSENSE_gc;  // read temperature
+        ADC0.CTRLC = ADC_SAMPCAP_bm | ADC_PRESC_DIV64_gc | ADC_REFSEL_INTREF_gc; // Internal ADC reference
     #else
         #error Unrecognized MCU type
     #endif
@@ -66,6 +69,15 @@ inline void set_admux_voltage() {
             ADMUXA = ADMUXA_VCC;
             ADMUXB = ADMUXB_VCC;
         #endif
+    #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc
+        #ifdef USE_VOLTAGE_DIVIDER  // 1.1V / ADC input pin
+            // verify that this is correct!!!  untested
+            ADC0.MUXPOS = ADMUX_VOLTAGE_DIVIDER;  // read the requested ADC pin
+            ADC0.CTRLC = ADC_SAMPCAP_bm | ADC_PRESC_DIV64_gc | ADC_REFSEL_INTREF_gc; // Use internal ADC reference
+        #else  // VCC / 1.1V reference
+            ADC0.MUXPOS = ADC_MUXPOS_INTREF_gc;  // read internal reference
+            ADC0.CTRLC = ADC_SAMPCAP_bm | ADC_PRESC_DIV64_gc | ADC_REFSEL_VDDREF_gc; // Vdd (Vcc) be ADC reference
+        #endif
     #else
         #error Unrecognized MCU type
     #endif
@@ -77,6 +89,9 @@ inline void set_admux_voltage() {
 inline void ADC_start_measurement() {
     #if (ATTINY == 25) || (ATTINY == 45) || (ATTINY == 85) || (ATTINY == 841) || (ATTINY == 1634)
         ADCSRA |= (1 << ADSC) | (1 << ADIE);
+    #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc
+        ADC0.INTCTRL |= ADC_RESRDY_bm; // enable interrupt
+        ADC0.COMMAND |= ADC_STCONV_bm; // Start the ADC conversions
     #else
         #error unrecognized MCU type
     #endif
@@ -108,13 +123,22 @@ inline void ADC_on()
         // enable, start, auto-retrigger, prescale
         ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADATE) | ADC_PRSCL;
         //ADCSRA |= (1 << ADSC);  // start measuring
+    #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc
+        set_admux_voltage();
+        VREF.CTRLA |= VREF_ADC0REFSEL_1V1_gc; // Set Vbg ref to 1.1V
+        ADC0.CTRLA = ADC_ENABLE_bm | ADC_FREERUN_bm; // Enabled, free-running (aka, auto-retrigger)
+        ADC0.COMMAND |= ADC_STCONV_bm; // Start the ADC conversions    
     #else
         #error Unrecognized MCU type
     #endif
 }
 
 inline void ADC_off() {
-    ADCSRA &= ~(1<<ADEN); //ADC off
+    #ifdef AVRXMEGA3  // ATTINY816, 817, etc
+        ADC0.CTRLA &= ~(ADC_ENABLE_bm);  // disable the ADC 
+    #else
+        ADCSRA &= ~(1<<ADEN); //ADC off
+    #endif
 }
 
 #ifdef USE_VOLTAGE_DIVIDER
@@ -140,9 +164,16 @@ static inline uint8_t calc_voltage_divider(uint16_t value) {
 #define ADC_CYCLES_PER_SECOND 2
 #endif
 
+#ifdef AVRXMEGA3  // ATTINY816, 817, etc
+#define ADC_vect ADC0_RESRDY_vect
+#endif
 // happens every time the ADC sampler finishes a measurement
 ISR(ADC_vect) {
 
+    #ifdef AVRXMEGA3  // ATTINY816, 817, etc
+    ADC0.INTFLAGS = ADC_RESRDY_bm; // clear the interrupt
+    #endif
+
     if (adc_sample_count) {
 
         uint16_t m;  // latest measurement
@@ -150,7 +181,23 @@ ISR(ADC_vect) {
         uint8_t channel = adc_channel;
 
         // update the latest value
+        #ifdef AVRXMEGA3  // ATTINY816, 817, etc
+        // Use the factory calibrated values in SIGROW.TEMPSENSE0 and SIGROW.TEMPSENSE1
+        // to calculate a temperature reading in Kelvin, then left-align it. 
+        if (channel == 1) { // thermal, convert ADC reading to left-aligned Kelvin
+            int8_t sigrow_offset = SIGROW.TEMPSENSE1; // Read signed value from signature row
+            uint8_t sigrow_gain = SIGROW.TEMPSENSE0; // Read unsigned value from signature row
+            uint32_t temp = ADC0.RES - sigrow_offset;
+            temp *= sigrow_gain; // Result might overflow 16 bit variable (10bit+8bit)
+            temp += 0x80; // Add 1/2 to get correct rounding on division below
+            temp >>= 8; // Divide result to get Kelvin
+            m = (temp << 6); // left align it
+        } 
+        else { m = (ADC0.RES << 6); } // voltage, force left-alignment
+
+        #else
         m = ADC;
+        #endif
         adc_raw[channel] = m;
 
         // lowpass the value
@@ -181,8 +228,12 @@ void adc_deferred() {
     // real-world entropy makes this a true random, not pseudo
     // Why here instead of the ISR?  Because it makes the time-critical ISR
     // code a few cycles faster and we don't need crypto-grade randomness.
+    #ifdef AVRXMEGA3  // ATTINY816, 817, etc
+    pseudo_rand_seed += ADC0.RESL; // right aligned, not left... so should be equivalent?
+    #else
     pseudo_rand_seed += (ADCL >> 6) + (ADCH << 2);
     #endif
+    #endif
 
     // the ADC triggers repeatedly when it's on, but we only need to run the
     // voltage and temperature regulation stuff once in a while...so disable
-- 
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