added *unfinished* support for avr32dd20, plus a build target for a dev kit

ADC doesn't work yet.  No voltage, no temperature.
I need to do a lot of refactoring on the ADC code.  :(

1 files changed, 263 insertions, 0 deletions

diff --git a/arch/avr32dd20.c b/arch/avr32dd20.c
new file mode 100644
index 0000000..45923a8
--- /dev/null
+++ b/arch/avr32dd20.c
@@ -0,0 +1,263 @@
+// arch/avr32dd20.h: avr32dd20 support header
+// Copyright (C) 2023 Selene ToyKeeper
+// SPDX-License-Identifier: GPL-3.0-or-later
+#pragma once
+
+////////// clock speed / delay stuff //////////
+
+inline void mcu_clock_speed() {
+    // TODO: allow hwdef to define a base clock speed
+    // run the internal clock at 12 MHz, not the default 4 MHz
+    _PROTECTED_WRITE( CLKCTRL.OSCHFCTRLA,
+                      CLKCTRL_FRQSEL_12M_gc | CLKCTRL_AUTOTUNE_bm );
+    // (another option is to use 20 MHz / 2, like attiny1616 does)
+    // divide 20 MHz to run at 10 MHz to match attiny1616
+    //_PROTECTED_WRITE( CLKCTRL.MCLKCTRLB,
+    //                  CLKCTRL_PDIV_2X_gc | CLKCTRL_PEN_bm );
+}
+
+///// clock dividers
+// this should work, but needs further validation
+inline void clock_prescale_set(uint8_t n) {
+    cli();
+    _PROTECTED_WRITE(CLKCTRL.MCLKCTRLB, n); // Set the prescaler
+    while (CLKCTRL.MCLKSTATUS & CLKCTRL_SOSC_bm) {} // wait for clock change to finish
+    sei();
+}
+
+
+////////// ADC voltage / temperature //////////
+
+// ADC0.CTRLA bits:
+//   RUNSTDBY, -, CONVMODE, LEFTADJ, RESSEL[1:0], FREERUN, ENABLE
+// CTRLB bits:  -, -, -, -, -, SAMPNUM[2:0]
+// CTRLC bits:  -, -, -, -, PRESC[3:0]
+// CTRLD bits:  INITDLY[2:0], -, SAMPDLY[3:0]
+// CTRLE bits:  -, -, -, -, -, WINCM[2:0]
+// SAMPCTRL: 8 bits
+// MUXPOS, MUXNEG: 7 bits each
+// COMMAND:  -, -, -, -, -, -, SPCONV, STCONV
+
+inline void mcu_set_admux_therm() {
+    // ADC init: Datasheet section 33.3.2
+    // Temperature mode: Datasheet section 33.3.3.8
+    // measurements should be 12-bit right-adjusted single-ended conversion
+    // set Vref to 2.048V for temperature mode
+    VREF.ADC0REF = VREF_REFSEL_2V048_gc;
+    // set temp sensor as input
+    ADC0.MUXPOS = ADC_MUXPOS_TEMPSENSE_gc;
+    // configure init delay to >= 25 us * Fclk_adc (no sample delay needed)
+    ADC0.CTRLD = ADC_INITDLY_DLY32_gc | ADC_SAMPDLY_DLY0_gc;
+    // configure ADC sample length to >= 28 us * Fclk_adc
+    ADC0.SAMPCTRL = 32;
+    // set single-ended or differential
+    // set resolution to 12 bits
+    // set left- or right-adjust (right)
+    // set free-running mode or not (yes)
+    ADC0.CTRLA = ADC_CONVMODE_SINGLEENDED_gc
+               | ADC_RESSEL_12BIT_gc
+               //| ADC_LEFTADJ_bm  // not in temperature mode
+               | ADC_FREERUN_bm;
+    // set number of samples (requires adjustment in formula too)
+    ADC0.CTRLB = ADC_SAMPNUM_NONE_gc;
+    // TODO: accumulate more samples for more resolution
+    // (and probably set the prescale faster too)
+    //ADC0.CTRLB = ADC_SAMPNUM_ACC16_gc;  // 16 samples per result
+    // set a clock prescaler
+    ADC0.CTRLC = ADC_PRESC_DIV64_gc;
+    // enable the ADC
+    ADC0.CTRLA |= ADC_ENABLE_bm;
+    // actually start measuring (happens in another function)
+    //ADC0.COMMAND |= ADC_STCONV_bm;
+    // for each measurement:
+    // process according to sigrow data + formula
+}
+
+inline void mcu_set_admux_voltage() {
+    // ADC init: Datasheet section 33.3.2
+    // set Vref
+    VREF.ADC0REF = VREF_REFSEL_1V024_gc;
+    // set single-ended or differential
+    // set resolution to 12 bits
+    // set left- or right-adjust (right)
+    // set free-running mode or not (yes)
+    ADC0.CTRLA = ADC_CONVMODE_SINGLEENDED_gc
+               | ADC_RESSEL_12BIT_gc
+               | ADC_LEFTADJ_bm  // has no effect when 16+ samples taken
+               | ADC_FREERUN_bm
+               | ADC_RUNSTBY_bm  // allow voltage sense in standby mode
+               ;
+    // set number of samples
+    ADC0.CTRLB = ADC_SAMPNUM_ACC16_gc;  // 16 samples per result
+    // set a clock prescaler
+    ADC0.CTRLC = ADC_PRESC_DIV16_gc;  // not too fast, not too slow
+    // select the positive ADC input with MUXPOS
+    #ifdef USE_VOLTAGE_DIVIDER  // external voltage divider
+        // ADC input pin / Vref
+        ADC0.MUXPOS = ADMUX_VOLTAGE_DIVIDER;  // external pin
+    #elif defined (USE_VOLTAGE_VDDIO2)  // internal voltage divider
+        // (Vbat / 10) / Vref
+        ADC0.MUXPOS = ADC_MUXPOS_VDDIO2DIV10_gc;
+    #else  // measure directly on VDD/VCC pin
+        // (Vbat / 10) / Vref
+        ADC0.MUXPOS = ADC_MUXPOS_VDDDIV10_gc;
+    #endif
+    // enable the ADC
+    ADC0.CTRLA |= ADC_ENABLE_bm;
+    // actually start measuring (happens in another function)
+    //ADC0.COMMAND |= ADC_STCONV_bm;
+}
+
+inline void mcu_adc_sleep_mode() {
+    set_sleep_mode(SLEEP_MODE_STANDBY);
+}
+
+inline void mcu_adc_start_measurement() {
+    // FIXME: enable this after getting ADC stuff fixed
+    #if 0
+    ADC0.INTCTRL |= ADC_RESRDY_bm; // enable interrupt
+    ADC0.COMMAND |= ADC_STCONV_bm; // actually start measuring
+    #endif
+}
+
+/*
+void mcu_adc_on() {
+    hwdef_set_admux_voltage();
+    mcu_adc_start_measurement();
+}
+*/
+
+inline void mcu_adc_off() {
+    ADC0.CTRLA &= ~(ADC_ENABLE_bm);  // disable the ADC
+}
+
+inline void mcu_adc_vect_clear() {
+    ADC0.INTFLAGS = ADC_RESRDY_bm; // clear the interrupt
+}
+
+inline uint16_t mcu_adc_result_temp() {
+    // FIXME: better math, higher precision
+    // Use the factory calibrated values in SIGROW.TEMPSENSE0 and
+    // SIGROW.TEMPSENSE1 to calculate a temperature reading in Kelvin, then
+    // left-align it.
+    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
+    //return temp << 6;  // left align it
+    return temp >> 2;  // left-aligned uint16_t
+}
+
+inline uint16_t mcu_adc_result_volts() {
+    // voltage is 12-bit right-aligned + 16x oversampling = 16 bits total
+    return ADC0.RES;
+}
+
+inline uint8_t mcu_adc_lsb() {
+    // temp is right-aligned, voltage is 16-bit, both have a useful LSB
+    return ADC0_RESL;
+}
+
+#ifdef USE_VOLTAGE_VDD
+uint8_t calc_voltage(uint16_t measurement) {
+    // calculate actual voltage: volts * 10
+    // FIXME
+    // ADC = 1.1 * 1024 / volts
+    // volts = 1.1 * 1024 / ADC
+    result = ((uint16_t)(2*1.1*1024*10)/(measurement>>6)
+              + VOLTAGE_FUDGE_FACTOR
+              #ifdef USE_VOLTAGE_CORRECTION
+                  + VOLT_CORR - 7
+              #endif
+              ) >> 1;
+    return result;
+}
+#elif defined(USE_VOLTAGE_VDDIO2)
+#elif defined(USE_VOLTAGE_VDDIO2)
+#else
+// hwdef must supply its own function
+#endif
+
+////////// WDT //////////
+// this uses the RTC PIT interrupt instead of WDT,
+// as recommended on AVR 0/1-series and later:
+// https://github.com/SpenceKonde/DxCore/blob/master/megaavr/extras/PowerSave.md#using-the-real-time-counter-rtcpit
+// The PIT runs even in power-down mode, unlike RTC,
+// and its cycles are relative to the AVR's internal 32768 Hz ULP oscillator
+// AVR datasheet sections 26, 26.5, 26.9, 26.12, 26.13.12
+
+// PIT tick speeds:
+//  0   (none)
+//  1  8192 Hz (CYC4)
+//  2  4096 Hz
+//  3  2048 Hz
+//  4  1024 Hz (CYC32)
+//  5   512 Hz
+//  6   256 Hz
+//  7   128 Hz
+//  8    64 Hz (default) (CYC512)
+inline void mcu_wdt_active() {
+    RTC.PITINTCTRL = RTC_PI_bm;   // enable the Periodic Interrupt
+    while (RTC.PITSTATUS > 0) {}  // make sure the register is ready to be updated
+    // Period = 16ms (64 Hz), enable the PI Timer
+    RTC.PITCTRLA = RTC_PERIOD_CYC512_gc | RTC_PITEN_bm;
+}
+
+// STANDBY_TICK_SPEED:
+//  0   64 Hz
+//  1   32 Hz
+//  2   16 Hz
+//  3    8 Hz (default)
+//  4    4 Hz
+//  5    2 Hz
+//  6    1 Hz
+inline void mcu_wdt_standby() {
+    RTC.PITINTCTRL = RTC_PI_bm;   // enable the Periodic Interrupt
+    while (RTC.PITSTATUS > 0) {}  // make sure the register is ready to be updated
+    // Set period (64 Hz / STANDBY_TICK_SPEED = 8 Hz), enable the PI Timer
+    RTC.PITCTRLA = ((8+STANDBY_TICK_SPEED)<<3) | RTC_PITEN_bm;
+}
+
+inline void mcu_wdt_stop() {
+    while (RTC.PITSTATUS > 0) {}  // make sure the register is ready to be updated
+    RTC.PITCTRLA = 0; // Disable the PI Timer
+}
+
+inline void mcu_wdt_vect_clear() {
+    RTC.PITINTFLAGS = RTC_PI_bm; // clear the PIT interrupt flag
+}
+
+
+////////// PCINT - pin change interrupt (e-switch) //////////
+
+inline void mcu_switch_vect_clear() {
+    // Write a '1' to clear the interrupt flag
+    SWITCH_INTFLG |= (1 << SWITCH_PIN);
+}
+
+inline void mcu_pcint_on() {
+    SWITCH_ISC_REG |= PORT_ISC_BOTHEDGES_gc;
+}
+
+inline void mcu_pcint_off() {
+    SWITCH_ISC_REG &= ~(PORT_ISC_gm);
+}
+
+
+////////// misc //////////
+
+void reboot() {
+    // request a reboot (software reset)
+    _PROTECTED_WRITE(RSTCTRL.SWRR, RSTCTRL_SWRST_bm);
+}
+
+inline void prevent_reboot_loop() {
+    // if previous reset was a crash (WDT time-out),
+    // prevent it from happening again immediately
+    //RSTCTRL.RSTFR &= ~(RSTCTRL_WDRF_bm);  // reset wdt flag only
+    RSTCTRL.RSTFR = 0;  // reset all reset status flags (maybe unneeded?)
+    wdt_disable();  // from avr/wdt.h
+}
+