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/*
* Copyright 2013-2014 Ettus Research LLC
*
* This program 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 3 of the License, or
* (at your option) any later version.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* Welcome to the firmware code for the USRP Octoclock accessory product!
*
* Notes regarding this firmware:
* NOT in M103 compatibility mode
* CKOPT full rail-to-rail
* xtal osc
* 16K CK (16K clock cycles)
* additional delay 65ms for Crystal Oscillator
* slowly rising power
* persistent EEPROM
*
* These settings are very conservative. If a lower power oscillator is
* required, change CKOPT to '1' (UNPROGRAMMED).
*
* M103C = [ ]
* WDTON = [ ]
* OCDEN = [ ]
* JTAGEN = [X]
* SPIEN = [X]
* EESAVE = [X]
* BOOTSZ = 4095W_F000
* BOOTRST = [ ]
* CKOPT = [X]
* BODLEVEL = 2V7
* BODEN = [ ]
* SUT_CKSEL = EXTHIFXTALRES_16KCK_64MS
*
* EXTENDED = 0xFF (valid)
* HIGH = 0x81 (valid)
* LOW = 0xFF (valid)
*
*/
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <avr/eeprom.h>
#include <avr/interrupt.h>
#include <avr/io.h>
#include <avrlibdefs.h>
#include <octoclock.h>
#include <debug.h>
#include <clkdist.h>
#include <state.h>
#include <network.h>
#include <usart.h>
#include <net/udp_handlers.h>
/*
* Timer 3 (16-bit)
* * Set input capture trigger to rising edge
* * Set prescaler to 1
* * Enable overflow interrupt
* * Set timer to 0
*/
#define TIMER3_INIT() TCCR3B = (1 << ICES3) | (1 << CS30); \
ETIMSK |= (1 << TOIE3); \
TCNT3 = 0; \
ICR3 = 0;
/*
* We use TIMER3 as a watchdog timer for external reference
* detection. Once a signal is detected, we allow for five
* timer overflows (~26 ms) without another signal before
* deciding that there is no external reference connected.
*/
#define EXT_REF_TIMEOUT 5
static volatile uint16_t num_overflows = 0;
static uint16_t current_num_overflows = 0;
static uint16_t prev_num_overflows = 0;
static uint16_t current_ICR3 = 0;
static uint16_t prev_ICR3 = 0;
static ref_t prev_ref = NO_REF;
static switch_pos_t prev_switch_pos = PREFER_EXTERNAL;
bool top = false;
ISR(TIMER3_OVF_vect){
num_overflows++;
}
/*******************************************************************************
* Main Routine
*******************************************************************************/
int main(void){
/*
* Initializations
*/
cli();
// Make sure interrupts belong to us
MCUCR = (1<<IVCE);
MCUCR = 0;
// Initialize global variables
g_ext_ref_present = false;
g_gps_present = false;
g_switch_pos = PREFER_INTERNAL;
g_ref = NO_REF;
// Atmega128
setup_atmel_io_ports();
// Reset ClkDist chip
reset_TI_CDCE18005();
// GPSDO communication
usart_init();
// Ethernet stack
network_init();
register_udp_listener(OCTOCLOCK_UDP_CTRL_PORT, handle_udp_ctrl_packet);
register_udp_listener(OCTOCLOCK_UDP_GPSDO_PORT, handle_udp_gpsdo_packet);
// Timers
TIMER1_INIT(); // Network
TIMER3_INIT(); // External reference check
// Debug (does nothing when not in debug mode)
DEBUG_INIT();
DEBUG_LOG(" "); // Force a newline between runs
leds_off();
sei();
// Check if GPS present (should only need to happen once)
g_gps_present = (PIND & (1<<DDD4));
// State of previous iteration
prev_ref = NO_REF;
prev_switch_pos = PREFER_EXTERNAL;
cli();
prev_ICR3 = ICR3;
sei();
prev_num_overflows = 0;
/*
* Main loop
*/
while(true){
// Check switch position
g_switch_pos = (PINC & (1<<DDC1)) ? PREFER_EXTERNAL : PREFER_INTERNAL;
/*
* Check input capture pin for external reference detection.
*
* 16-bit reads could be corrupted during an interrupt, so
* disable interrupts for safety.
*/
cli();
current_ICR3 = ICR3;
current_num_overflows = num_overflows;
sei();
// Signal detected, reset timer
if(current_ICR3 != prev_ICR3){
cli();
TCNT3 = 0;
num_overflows = 0;
sei();
g_ext_ref_present = true;
}
// Timeout, no external reference detected
if(current_num_overflows >= EXT_REF_TIMEOUT){
g_ext_ref_present = false;
}
// Determine and set reference based on state
if(!g_gps_present && !g_ext_ref_present) g_ref = NO_REF;
else if(g_gps_present && !g_ext_ref_present) g_ref = INTERNAL;
else if(!g_gps_present && g_ext_ref_present) g_ref = EXTERNAL;
else g_ref = (g_switch_pos == PREFER_INTERNAL) ? INTERNAL : EXTERNAL;
if((g_ref != prev_ref) || (g_switch_pos != prev_switch_pos)){
if(g_switch_pos == PREFER_INTERNAL) prefer_internal();
else prefer_external();
}
// Record this iteration's state
prev_ref = g_ref;
prev_switch_pos = g_switch_pos;
prev_ICR3 = current_ICR3;
prev_num_overflows = current_num_overflows;
// Handle incoming Ethernet packets
network_check();
}
}
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