#include <stdbool.h>
-
// Pins
enum {
AREF_PIN = PORT_A << 3,
TEMP_ADC, // Temperature
};
+
+#define CAP_CHARGE_TIME 100 // ms
+#define CAP_CHARGE_MAX_DUTY 0.5
+#define VOLTAGE_MIN 11
+#define VOLTAGE_MAX 39
+#define CURRENT_MAX 25
+#define VOLTAGE_SETTLE_COUNT 5
+#define VOLTAGE_SETTLE_PERIOD 20 // ms
+#define VOLTAGE_SETTLE_TOLERANCE 0.01
+#define VOLTAGE_EXP 0.01
+#define FAULT_TIMEOUT 5000 // ms
+
+#define SHUNT_WATTS_PER_SEC 5
+#define SHUNT_OHMS 10
+#define SHUNT_MIN_V 1
+#define SHUNT_MAX_V 3
+
#define I2C_ADDR 0x60
#define I2C_MASK 0b00000111
LOAD1_REG,
LOAD2_REG,
VDD_REG,
+ FLAGS_REG,
NUM_REGS
} regs_t;
+enum {
+ UNDER_VOLTAGE_FLAG = 1 << 0,
+ OVER_VOLTAGE_FLAG = 1 << 1,
+ OVER_CURRENT_FLAG = 1 << 2,
+};
+
+
static const uint8_t ch_schedule[] = {
TEMP_ADC, VOUT_ADC,
VIN_ADC, VOUT_ADC,
// Stretch clock longer to work around RPi bug
// See https://github.com/raspberrypi/linux/issues/254
- _delay_us(10);
+ _delay_us(10); // Must use software delay while in interrupt
uint8_t status = TWSSRA;
}
+static float get_total_current() {
+ cli();
+ float current =
+ regs[MOTOR_REG] + regs[VDD_REG] + regs[LOAD1_REG] + regs[LOAD2_REG];
+ sei();
+
+ return current / 100;
+}
+
+
+static float get_reg(int reg) {
+ cli();
+ float value = regs[reg];
+ sei();
+
+ return value / 100;
+}
+
+
+static volatile uint64_t time = 0; // ms
+static volatile float shunt_ms_power = 0;
+
+
+static void update_shunt() {
+ static float watts = SHUNT_WATTS_PER_SEC;
+
+ // Add power dissipation credit
+ watts += SHUNT_WATTS_PER_SEC / 1000.0;
+ if (SHUNT_WATTS_PER_SEC < watts) watts = SHUNT_WATTS_PER_SEC;
+
+ // Remove power dissipation credit
+ watts -= shunt_ms_power;
+ if (watts < 0) watts = 0;
+
+ // Enable shunt output when requested if allowed
+ if (shunt_ms_power) {
+ IO_DDR_SET(SHUNT_PIN); // Enable shunt output
+
+ if (watts) IO_DDR_SET(MOTOR_PIN); // Enable motor output
+ else IO_DDR_CLR(MOTOR_PIN); // Disable motor output
+
+ } else {
+ IO_DDR_CLR(SHUNT_PIN); // Disable output
+ IO_DDR_SET(MOTOR_PIN); // Enable motor output
+ }
+}
+
+
+static void update_shunt_power(float vout, float vnom) {
+ if (vnom + SHUNT_MIN_V < vout) {
+ float duty = (vout - vnom - SHUNT_MIN_V) / SHUNT_MAX_V;
+ if (duty < 0) duty = 0;
+ if (1 < duty) duty = 1;
+
+ // Compute the power credits used per ms
+ shunt_ms_power = vout * vout * duty * (1.0 / SHUNT_OHMS / 1000.0);
+ OCR1A = 0xff * duty;
+
+ } else shunt_ms_power = 0;
+}
+
+
+static volatile float vnom = 0;
+
+static void measure_nominal_voltage() {
+ float vin = get_reg(VIN_REG);
+ float v;
+
+ if (vnom < VOLTAGE_MIN) v = vin;
+ else v = vnom * (1 - VOLTAGE_EXP) + vin * VOLTAGE_EXP;
+
+ if (36 < v) v = 36; // TODO remove this when R27 is updated
+
+ vnom = v;
+}
+
+
+ISR(TIMER0_OVF_vect) {
+ static uint8_t tick = 0;
+ if (++tick == 31) {
+ time++;
+ tick = 0;
+
+ update_shunt();
+ if (!(time & 7)) measure_nominal_voltage();
+ }
+}
+
+
+static void delay_ms(uint16_t ms) {
+ uint64_t start = time;
+ while (time < start + ms) continue;
+}
+
+
inline static uint16_t convert_voltage(uint16_t sample) {
#define VREF 1.1
#define VR1 34800 // TODO v10 will have 37.4k
}
-void adc_conversion() {
+static void adc_conversion() {
static int8_t i = 0;
read_conversion(ch_schedule[i]);
ISR(ADC_vect) {adc_conversion();}
+static bool is_within(float a, float b, float tolerance) {
+ return a * (1 - tolerance) < b && b < a * (1 + tolerance);
+}
+
+
+static void validate_input_voltage() {
+ int settle = 0;
+ float vlast = 0;
+
+ while (settle < VOLTAGE_SETTLE_COUNT) {
+ wdt_reset();
+ delay_ms(VOLTAGE_SETTLE_PERIOD);
+
+ float vin = get_reg(VIN_REG);
+
+ // Check that voltage is with in range and settled
+ if (VOLTAGE_MIN < vin && vin < VOLTAGE_MAX &&
+ is_within(vlast, vin, VOLTAGE_SETTLE_TOLERANCE)) settle++;
+ else settle = 0;
+
+ vlast = vin;
+ }
+}
+
+
+static void charge_caps() {
+ TCCR0A |= (1 << COM0A1) | (0 << COM0A0); // Clear on compare match
+ IO_PORT_CLR(MOTOR_PIN); // Motor voltage on
+ IO_DDR_SET(MOTOR_PIN); // Output
+
+ uint64_t now = time;
+ for (int i = 0; i < CAP_CHARGE_TIME; i++) {
+ OCR0A = 0xff * CAP_CHARGE_MAX_DUTY / CAP_CHARGE_TIME * (i + 1);
+ while (time == now) continue;
+ now++;
+ }
+
+ TCCR0A &= ~((1 << COM0A1) | (1 << COM0A0));
+ IO_PORT_SET(MOTOR_PIN); // Motor voltage on
+}
+
+
+static void disable_outputs() {
+ IO_PORT_CLR(MOTOR_PIN);
+ IO_PORT_CLR(LOAD1_PIN);
+ IO_PORT_CLR(LOAD2_PIN);
+ IO_DDR_SET(LOAD1_PIN);
+ IO_DDR_SET(LOAD2_PIN);
+}
+
+
+static void enable_outputs() {
+ IO_PORT_SET(MOTOR_PIN);
+ IO_DDR_CLR(LOAD1_PIN);
+ IO_DDR_CLR(LOAD2_PIN);
+}
+
+
void init() {
cli();
(0 << PRTIM0) | (0 << PRTIM1) | (0 << PRTWI);
// IO
- IO_DDR_SET(MOTOR_PIN); // Output
+ IO_PORT_CLR(MOTOR_PIN); // Motor voltage off
IO_DDR_SET(LOAD1_PIN); // Output
IO_DDR_SET(LOAD2_PIN); // Output
IO_PUE_SET(PWR_RESET); // Pull up reset line
(1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
ADCSRB = 0;
- // Timer 0 (Clear output A on compare match, Fast PWM, disabled)
- TCCR0A = (1 << COM0A1) | (0 << COM0A0) | (1 << WGM01) | (1 << WGM00);
- TCCR0B = 0 << WGM02;
+ // Timer 0 (Fast PWM, clk/1)
+ TCCR0A = (1 << WGM01) | (1 << WGM00);
+ TCCR0B = (0 << WGM02) | (0 << CS02) | (0 << CS01) | (1 << CS00);
+ TIMSK = 1 << TOIE0; // Enable overflow interrupt
// Timer 1 (Set output A on compare match, Fast PWM, 8-bit, no prescale)
OCR1A = 0; // Off
}
-float get_reg(int reg) {
- cli();
- float value = regs[reg];
- sei();
-
- return value / 100;
-}
-
-
int main() {
wdt_enable(WDTO_8S);
init();
+ adc_conversion(); // Start ADC
+ validate_input_voltage();
+ charge_caps();
- // Start ADC
- adc_conversion();
-
- // Validate input voltage
- int settle = 0;
- float vlast = 0;
-
- while (settle < 5) {
+ while (true) {
wdt_reset();
- _delay_ms(20);
float vin = get_reg(VIN_REG);
-
- // Check that voltage is with in range and settled
- if (11 < vin && vin < 39 && vlast * 0.98 < vin && vin < vlast * 1.02)
- settle++;
- else settle = 0;
-
- vlast = vin;
- }
-
- // Charge caps
- OCR0A = 255 * 0.2; // Cap charging duty cycle
- TCCR0B |= (0 << CS02) | (1 << CS01) | (0 << CS00); // Enable timer with clk/8
- _delay_ms(200);
- TCCR0A = 0; // Clock off
- IO_PORT_SET(MOTOR_PIN); // Motor voltage on
-
- _delay_ms(50); // Wait for final charge
-
- // Measure nominal voltage
- float vnom = 0;
- settle = 0;
- while (settle < 5) {
- wdt_reset();
- _delay_ms(20);
-
float vout = get_reg(VOUT_REG);
- // Check that voltages are with in range and vout has settled
- if (11 < vout && vout < 39 && vout * 0.98 < vnom && vnom < vout * 1.02)
- settle++;
- else settle = 0;
+ update_shunt_power(vout, vnom);
- vnom = vout;
- }
-
- if (36 < vnom) vnom = 36; // TODO remove this when R27 is updated
-
- bool shunt = false;
-
- while (true) {
- wdt_reset();
- float vout = get_reg(VOUT_REG);
-
- if (!shunt && vnom + 2 < vout) {
- shunt = true;
- IO_DDR_SET(SHUNT_PIN); // Enable output
-
- } else if (shunt && vout < vnom + 1) {
- IO_DDR_CLR(SHUNT_PIN); // Disable output
- shunt = false;
- }
-
- if (shunt) {
- float duty = (vout - vnom - 1) / 4;
- if (1 < duty) OCR1A = 0xff;
- else OCR1A = 0xff * duty;
- }
-
- continue;
-
- if (39 < get_reg(VIN_REG) || get_reg(VIN_REG) < 11) {
- IO_PORT_CLR(MOTOR_PIN);
- _delay_ms(3000);
- IO_PORT_SET(MOTOR_PIN); // Motor voltage on
- }
+ uint16_t flags = 0;
+ if (vin < VOLTAGE_MIN) flags |= UNDER_VOLTAGE_FLAG;
+ if (VOLTAGE_MAX < vin) flags |= OVER_VOLTAGE_FLAG;
+ if (CURRENT_MAX < get_total_current()) flags |= OVER_CURRENT_FLAG;
+ regs[FLAGS_REG] = flags;
- if (10 < get_reg(MOTOR_REG)) {
- IO_PORT_CLR(MOTOR_PIN);
- IO_PORT_CLR(LOAD1_PIN);
- IO_PORT_CLR(LOAD2_PIN);
- _delay_ms(1000);
- IO_PORT_SET(MOTOR_PIN); // Motor voltage on
+ if (flags) {
+ disable_outputs();
+ delay_ms(FAULT_TIMEOUT);
+ enable_outputs();
}
}
projects / bbctrl-firmware / commitdiff