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Diffstat (limited to 'ezdop/src/firmware/dopctrl.c')
| -rw-r--r-- | ezdop/src/firmware/dopctrl.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/ezdop/src/firmware/dopctrl.c b/ezdop/src/firmware/dopctrl.c new file mode 100644 index 000000000..f499d6c35 --- /dev/null +++ b/ezdop/src/firmware/dopctrl.c @@ -0,0 +1,193 @@ +/* + * AE6HO EZ-Doppler firmware for onboard ATmega8 microcontroller + * Copyright 2006 Free Software Foundation, Inc. + * + * This file is part of GNU Radio + * + * GNU Radio is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * GNU Radio is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Radio; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + */ + +/* + * ARCHITECTURE + * + * Timer0 is 8000 Hz time base + * PORTD.2 through PORTD.5 are doppler antenna array element enables. + * PORTB.0 is a diagnostic LED, set low to light up + * ADC7 is audio input + * ADC6 is RSSI input - not yet used + * + */ + +#include <avr/io.h> +#include <avr/interrupt.h> +#include <avr/signal.h> +#include "dopctrl.h" + +#define LED 0 +#define turn_off_led() PORTB |= _BV(LED); +#define turn_on_led() PORTB &= ~_BV(LED); + +#define ANT1 _BV(2) +#define ANT2 _BV(3) +#define ANT3 _BV(4) +#define ANT4 _BV(5) +#define ANTMASK ANT1|ANT2|ANT3|ANT4 + +#define ADCAIN 7 +#define BAUDRATE 250000 + +/* Assume these are all set to zero in startup code */ + +uint8_t rotate; /* Flag to indicate antennas should rotate or not */ +uint8_t streaming; /* Flag to indicate continuous sampling */ +uint8_t antennas; /* Holds shadow copy of PORTD antennas */ +uint8_t speed; /* Holds samples per phase increment */ +uint8_t phase; /* Holds rotation phase (measured in samples */ + +uint8_t audio_hi; /* High byte of ADC sample of audio */ +uint8_t audio_lo; /* Low byte of ADC sample of audio */ + +uint8_t rx; /* Temporary holds received byte from USART */ +uint8_t command; /* Temporary to hold command when getting operand */ +uint8_t cmdbyte; /* Tracks bytes received in multi-byte commands */ + +int main(void) +{ + /* Diagnostic port setup */ + DDRB = _BV(LED); /* PB0 is output */ + turn_off_led(); + + /* Antenna control port setup */ + speed = 4; /* Todo: read from EEPROM */ + antennas = ANT1; /* Start with antenna #1 */ + PORTD = antennas; /* Set port value */ + DDRD = ANTMASK; /* Set antenna enables as PORTD outputs */ + + /* ADC port setup */ + ADMUX = _BV(REFS0)|ADCAIN; /* AVCC is reference, use ADC for audio input (ADC7) */ + ADCSRA = _BV(ADEN)|_BV(ADIE)|0x07; /* Enable converter, prescale by 128, enable ADC interrupt */ + + /* USART port setup*/ + UCSRA = 0; /* Normal asynchronous mode */ + UCSRB = _BV(TXEN)|_BV(RXEN)|_BV(RXCIE); /* Enable transmitter and receiver, and receiver interrupts */ + UCSRC = _BV(URSEL)|_BV(UCSZ1)|_BV(UCSZ0); /* 8N1 format */ + UBRRH = 0; /* Set baud rate prescaler to 3 */ + UBRRL = 3; /* To get 250000 bps */ + + /* Set up 8000 Hz time base */ + timer_enable_int(_BV(TOIE0)); /* Turn on Timer0 output overflow interrupt */ + TCCR0 = _BV(CS01); /* Clock Timer0 from CLK/8 */ + + sei(); /* Let 'er rip! */ + return 0; +} + +/* Timer0 overflow interrupt handler + * + * Creates 8000 Hz time base, or 125us budget + * + */ +SIGNAL(SIG_OVERFLOW0) +{ + /* Reload Timer0 samples to 8, results in 8000 Hz overflow interrupt */ + TCNT0 = 0x08; + + if (streaming) { + /* Kick-off an audio sample conversion, will interrupt 104us later */ + ADCSRA |= _BV(ADSC); + + /* Write the first byte of previous sample and enable UDRIE */ + UDR = audio_lo; + UCSRB |= _BV(UDRIE); + } + + if (!rotate) /* Skip rotating antenna if not started */ + return; + + /* Increment antenna phase and see if antenna need to be rotated */ + if (++phase == speed) { + phase = 0; + + /* Sequence antenna array elements */ + antennas >>= 1; + antennas &= ANTMASK; + + if (!antennas) + antennas = ANT4; + PORTD = antennas; + } +} + +/* ADC conversion complete interrupt handler + * + * Read value and store. Assume prior sample has been handled. + * + */ +SIGNAL(SIG_ADC) +{ + audio_lo = ADCL; + audio_hi = ADCH; +} + +/* USART data transmit holding register empty interrupt handler + * + * First byte is always sent from timer interrupt + * So second byte gets sent here with UDRIE disabled + * + */ +SIGNAL(SIG_UART_DATA) +{ + /* Write second byte of previous sample and disable UDRIE */ + UDR = audio_hi | (antennas << 2); + UCSRB &= ~_BV(UDRIE); +} + +/* USART receive complete interrupt handler + * + * Received bytes are commands, with one or two bytes of operands following + * + */ +SIGNAL(SIG_UART_RECV) +{ + rx = UDR; + + if (cmdbyte == 0) { + if (rx == EZDOP_CMD_ROTATE) /* Start rotation */ + rotate = 1; + else if (rx == EZDOP_CMD_STOP) /* Stop rotation */ + rotate = 0; + else if (rx == EZDOP_CMD_RATE) { /* Set rotation rate */ + command = rx; + cmdbyte = 1; + } + else if (rx == EZDOP_CMD_STREAM) /* Stream audio samples */ + streaming = 1; + else if (rx == EZDOP_CMD_STROFF) /* Stop streaming */ + streaming = 0; + else + turn_on_led(); /* Unknown command */ + } + else if (cmdbyte == 1) { + if (command == EZDOP_CMD_RATE) { /* Operand is number of samples per phase increment */ + speed = rx; + cmdbyte = 0; + } + else + turn_on_led(); /* Bogus command state */ + } + else + turn_on_led(); /* Bogus command state */ +} |