X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=blobdiff_plain;f=src%2Fao_flight.c;h=81aecad3e26e0053059b65a90b7273a9504d627a;hp=5a9a8d801037c4d278abbc39d754e34053086ce3;hb=da42f406e88ccc821cd45d5a94d5afec65ec50e9;hpb=58838c0b96a91da0bd0cd77c3ff312b589c08136 diff --git a/src/ao_flight.c b/src/ao_flight.c index 5a9a8d80..81aecad3 100644 --- a/src/ao_flight.c +++ b/src/ao_flight.c @@ -146,16 +146,103 @@ ao_flight(void) ao_raw_pres = 0; ao_flight_tick = 0; for (;;) { - ao_sleep(&ao_adc_ring); + ao_wakeup(DATA_TO_XDATA(&ao_flight_adc)); + ao_sleep(DATA_TO_XDATA(&ao_adc_head)); while (ao_flight_adc != ao_adc_head) { __pdata uint8_t ticks; __pdata int16_t ao_vel_change; + __xdata struct ao_adc *ao_adc; ao_flight_prev_tick = ao_flight_tick; /* Capture a sample */ - ao_raw_accel = ao_adc_ring[ao_flight_adc].accel; - ao_raw_pres = ao_adc_ring[ao_flight_adc].pres; - ao_flight_tick = ao_adc_ring[ao_flight_adc].tick; + ao_adc = &ao_adc_ring[ao_flight_adc]; + ao_flight_tick = ao_adc->tick; + ao_raw_accel = ao_adc->accel; +#if HAS_ACCEL_REF + /* + * Ok, the math here is a bit tricky. + * + * ao_raw_accel: ADC output for acceleration + * ao_accel_ref: ADC output for the 5V reference. + * ao_cook_accel: Corrected acceleration value + * Vcc: 3.3V supply to the CC1111 + * Vac: 5V supply to the accelerometer + * accel: input voltage to accelerometer ADC pin + * ref: input voltage to 5V reference ADC pin + * + * + * Measured acceleration is ratiometric to Vcc: + * + * ao_raw_accel accel + * ------------ = ----- + * 32767 Vcc + * + * Measured 5v reference is also ratiometric to Vcc: + * + * ao_accel_ref ref + * ------------ = ----- + * 32767 Vcc + * + * + * ao_accel_ref = 32767 * (ref / Vcc) + * + * Acceleration is measured ratiometric to the 5V supply, + * so what we want is: + * + * ao_cook_accel accel + * ------------- = ----- + * 32767 ref + * + * + * accel Vcc + * = ----- * --- + * Vcc ref + * + * ao_raw_accel 32767 + * = ------------ * ------------ + * 32737 ao_accel_ref + * + * Multiply through by 32767: + * + * ao_raw_accel * 32767 + * ao_cook_accel = -------------------- + * ao_accel_ref + * + * Now, the tricky part. Getting this to compile efficiently + * and keeping all of the values in-range. + * + * First off, we need to use a shift of 16 instead of * 32767 as SDCC + * does the obvious optimizations for byte-granularity shifts: + * + * ao_cook_accel = (ao_raw_accel << 16) / ao_accel_ref + * + * Next, lets check our input ranges: + * + * 0 <= ao_raw_accel <= 0x7fff (singled ended ADC conversion) + * 0x7000 <= ao_accel_ref <= 0x7fff (the 5V ref value is close to 0x7fff) + * + * Plugging in our input ranges, we get an output range of 0 - 0x12490, + * which is 17 bits. That won't work. If we take the accel ref and shift + * by a bit, we'll change its range: + * + * 0xe000 <= ao_accel_ref<<1 <= 0xfffe + * + * ao_cook_accel = (ao_raw_accel << 16) / (ao_accel_ref << 1) + * + * Now the output range is 0 - 0x9248, which nicely fits in 16 bits. It + * is, however, one bit too large for our signed computations. So, we + * take the result and shift that by a bit: + * + * ao_cook_accel = ((ao_raw_accel << 16) / (ao_accel_ref << 1)) >> 1 + * + * This finally creates an output range of 0 - 0x4924. As the ADC only + * provides 11 bits of data, we haven't actually lost any precision, + * just dropped a bit of noise off the low end. + */ + ao_raw_accel = (uint16_t) ((((uint32_t) ao_raw_accel << 16) / (ao_accel_ref[ao_flight_adc] << 1))) >> 1; + ao_adc->accel = ao_raw_accel; +#endif + ao_raw_pres = ao_adc->pres; ao_flight_accel -= ao_flight_accel >> 4; ao_flight_accel += ao_raw_accel >> 4; @@ -216,36 +303,56 @@ ao_flight(void) ao_old_vel = ao_flight_vel; ao_old_vel_tick = ao_flight_tick; - /* Go to pad state if the nose is pointing up */ + /* Check to see what mode we should go to. + * - Invalid mode if accel cal appears to be out + * - pad mode if we're upright, + * - idle mode otherwise + */ ao_config_get(); - if (ao_config.accel_plus_g != 0 && - ao_config.accel_minus_g != 0 && - ao_flight_accel < ao_config.accel_plus_g + ACCEL_NOSE_UP && - ao_flight_accel > ao_config.accel_plus_g - ACCEL_NOSE_UP && - !ao_flight_force_idle) + if (ao_config.accel_plus_g == 0 || + ao_config.accel_minus_g == 0 || + ao_flight_accel < ao_config.accel_plus_g - ACCEL_NOSE_UP || + ao_flight_accel > ao_config.accel_minus_g + ACCEL_NOSE_UP) { + /* Detected an accel value outside -1.5g to 1.5g + * (or uncalibrated values), so we go into invalid mode + */ + ao_flight_state = ao_flight_invalid; + /* Allow packet mode in invalid flight state, + * Still need to be able to fix the problem! + */ + ao_packet_slave_start(); + + } else if (ao_flight_accel < ao_config.accel_plus_g + ACCEL_NOSE_UP && + !ao_flight_force_idle) + { + /* Set pad mode - we can fly! */ + ao_flight_state = ao_flight_pad; + /* Disable the USB controller in flight mode * to save power */ ao_usb_disable(); - /* Turn on telemetry system - */ + /* Turn on telemetry system */ ao_rdf_set(1); ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_PAD); - ao_flight_state = ao_flight_pad; - ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); + /* signal successful initialization by turning off the LED */ + ao_led_off(AO_LED_RED); } else { - ao_flight_state = ao_flight_idle; - - /* Turn on packet system in idle mode - */ + /* Set idle mode */ + ao_flight_state = ao_flight_idle; + + /* Turn on packet system in idle mode */ ao_packet_slave_start(); - ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); + + /* signal successful initialization by turning off the LED */ + ao_led_off(AO_LED_RED); } - /* signal successful initialization by turning off the LED */ - ao_led_off(AO_LED_RED); + /* wakeup threads due to state change */ + ao_wakeup(DATA_TO_XDATA(&ao_flight_state)); + break; case ao_flight_pad: