]> Pileus Git - ~andy/csm213a-hw/blobdiff - hw2/main.cpp
Cleanup comments and move test.cpp
[~andy/csm213a-hw] / hw2 / main.cpp
index 436f750508e6f815b32c6d2c617c8a054c2631dd..2c0f2746e716f3064431fc1ee08901322fb5167e 100644 (file)
-#include "mbed.h"\r
-\r
-/**\r
- * Mode of operation:\r
- *   Devices 1 and 2 synchronize clocks using serial messages.\r
- *\r
- *   1. Each serial message timestamped using the hardware timer capture\r
- *      registers in both the sender and receiver.\r
- *   2. The sender transmits the send timestamp during the next time-sync\r
- *      message.\r
- *   3. The receiver then compares the senders timestamp with it's own\r
- *      timestamp for the corresponding messages and calculates an offset.\r
- *   4. The offset is used to compensate the receivers local clock.\r
- *\r
- *   Time synchronization is performed in both directions.\r
- */\r
-\r
-/***********************\r
- * Message Definitions *\r
- ***********************/\r
-\r
-#define MSG_HEADER 0x1234\r
-\r
-typedef enum {\r
-       MSG_ID_SYNC,       // Time synchronization\r
-       MSG_ID_EVENT,      // Event occurred\r
-} msgid_t;\r
-\r
-typedef struct {\r
-       uint32_t seconds;  // Seconds since 1970 (without leap seconds)\r
-       uint32_t nanosec;  // Nanoseconds since 'seconds'\r
-} ntime_t;\r
-\r
-typedef struct {\r
-       uint16_t header;   // Message Header\r
-       uint16_t mesgid;   // Message ID\r
-       uint16_t length;   // Body length\r
-       uint16_t cksum;    // Body checksum\r
-} header_t;\r
-\r
-typedef struct {\r
-       uint16_t seq;      // Current sequence counter\r
-       uint16_t prev;     // Sequence of previous message\r
-       ntime_t  time;     // Time of previous message\r
-} sync_msg_t;\r
-\r
-typedef struct {\r
-       uint16_t device;   // Device ID\r
-       uint16_t event;    // Event ID\r
-       ntime_t  time;     // Timestamp\r
-} event_msg_t;\r
-\r
-/*******************\r
- * Timer functions *\r
- *******************/\r
-\r
-/**\r
- * Generate time stamp for an async event:\r
- *   time:  drift compensated wall-clock time\r
- *   stamp: event timestamp from Timer/PWM Module\r
- */\r
-void time_stamp(ntime_t *time, uint32_t stamp)\r
-{\r
-       // todo\r
-}\r
-\r
-/**\r
- * Compensate the Real-Time-Clock oscillator for\r
- * temperature and drift errors. Called at 1Hz and\r
- * synchronous to the RTC 1Hz output.\r
- */\r
-void time_rtc_comp(void)\r
-{\r
-       // todo\r
-}\r
-\r
-/**\r
- * Synchronize the timer internal state with updates\r
- * from an external time sync message.\r
- *   ours: our internal timestamp for the event\r
- *   ref:  reference timestamp from the other device\r
- */\r
-void time_ext_sync(ntime_t *ours, ntime_t *ref)\r
-{\r
-       // todo\r
-}\r
-\r
-/************************\r
- * Serial I/O functions *\r
- ************************/\r
-\r
-/**\r
- * Output time sync message\r
- */\r
-void serial_send_sync(void)\r
-{\r
-}\r
-\r
-/**\r
- * Output external event received message\r
- *   event: id of the received event\r
- *   time:  compensated timestamp of the event \r
- */\r
-void serial_send_event(uint16_t event, ntime_t *time)\r
-{\r
-}\r
-\r
-/**\r
- * Process serial receive messages\r
- */\r
-void serial_receive(void)\r
-{\r
-}\r
-\r
-/********************\r
- * Data definitions *\r
- ********************/\r
-\r
-DigitalOut led1(LED1);\r
-DigitalOut led2(LED2);\r
-\r
-/********\r
- * Main *\r
- ********/\r
-\r
-int main(int argc, char **argv)\r
-{\r
-    while (1) {\r
-        led1 = 1; led2 = 0; wait(0.1);\r
-        led1 = 0; led2 = 1; wait(0.1);\r
-    }\r
-}\r
+#include "messages.h"
+
+#include "mbed.h"
+#include "serial_irq.h"
+#include "serial_dma.h"
+#include "timer_dma.h"
+
+/**
+ * Mode of operation:
+ *   Devices 1 and 2 synchronize clocks using serial messages.
+ *
+ *   1. Each serial message timestamped using the hardware timer capture
+ *      registers in both the sender and receiver.
+ *   2. The sender transmits the send timestamp during the next time-sync
+ *      message.
+ *   3. The receiver then compares the senders timestamp with it's own
+ *      timestamp for the corresponding messages and calculates an offset.
+ *   4. The offset is used to compensate the receivers local clock.
+ *
+ *   Time synchronization is performed in both directions.
+ */
+
+/*******************
+ * Timer functions *
+ *******************/
+
+#define NSEC_PER_SEC 1000000000ULL
+
+uint64_t time_last_local; // timestamp at last time sync
+uint64_t time_last_world; // offset at last time sync
+
+/**
+ * Generate time stamp for an async event:
+ *   time:  drift compensated wall-clock time
+ *   stamp: event timestamp from PIT Module
+ */
+uint64_t time_to_world(uint64_t local)
+{
+       uint64_t elapsed = local - time_last_local;
+       return time_last_world + elapsed;
+}
+
+uint64_t time_to_local(uint64_t world)
+{
+       uint64_t elapsed = world - time_last_world;
+       return time_last_local + elapsed;
+}
+
+/**
+ * Synchronize the timer internal state with updates
+ * from an external time sync message.
+ *   local: our internal timestamp for the event
+ *   world: reference timestamp from the other device
+ */
+void time_ext_init(uint64_t local, uint64_t world)
+{
+       sirq_printf("initialize clocks: %d -> %d\r\n",
+                       (int)(local/NSEC_PER_SEC),
+                       (int)(world/NSEC_PER_SEC));
+
+       time_last_local = local;
+       time_last_world = world;
+}
+
+/**
+ * Synchronize the timer internal state with updates
+ * from an external time sync message.
+ *   local: our internal timestamp for the event
+ *   world: reference timestamp from the other device
+ */
+void time_ext_sync(uint64_t local, uint64_t world)
+{
+       uint64_t guess = time_to_world(local);
+
+       time_last_local = local;
+       time_last_world = (guess/2) + (world/2);
+       //time_last_world = (guess * 3 / 4) + (world * 1 / 4);
+       //time_last_world =
+       //      (guess - (        guess / 2)) +
+       //      (world - (world - world / 2));
+       //time_last_world =
+       //      (guess - (guess - guess / 4)) +
+       //      (world - (        world / 4));
+
+       world = time_last_world;
+
+//#ifdef VERBOSE
+#if 0
+       uint64_t error = world > guess ? world - guess :
+                        guess > world ? guess - world : 0;
+       int      ahead = guess > world;
+       sirq_printf("syncing clocks: %6d=%d.%04u -> %d.%04u (err: %s%ld.%09lu)\r\n",
+                       (int)((local / NSEC_PER_SEC)),
+                       (int)((guess / NSEC_PER_SEC)),
+                       (int)((guess % NSEC_PER_SEC)/(NSEC_PER_SEC/10000)),
+                       (int)((world / NSEC_PER_SEC)),
+                       (int)((world % NSEC_PER_SEC)/(NSEC_PER_SEC/10000)),
+                       ahead ? "-" : " ",
+                       (int32_t )(error / (int64_t)NSEC_PER_SEC),
+                       (uint32_t)(error % (int64_t)NSEC_PER_SEC));
+#endif
+//#endif
+}
+
+void time_printf(const char *label, uint64_t local)
+{
+       uint64_t world = time_to_world(local);
+       sirq_printf("%s -- %d.%09u -> %d.%09u\r\n",
+                       label,
+                       (int)(local / NSEC_PER_SEC),
+                       (int)(local % NSEC_PER_SEC),
+                       (int)(world / NSEC_PER_SEC),
+                       (int)(world % NSEC_PER_SEC));
+}
+
+/*********************
+ * Signal generation *
+ *********************/
+
+// for 50 Mhz clock  50/1000 = 1/20  (PLL/2)
+
+// for 48 Mhz clock  48/1000 = 6/125 (FLL)
+// for 24 Mhz clock, 24/1000 = 3/125
+// for 12 Mhz clock, 12/1000 = 3/250
+// for  6 Mhz clock,  6/1000 = 3/500
+// for  3 Mhz clock,  3/1000 = 3/1000
+
+#define EMIT_PS 1
+
+//#if EMIT_PS == 0
+//#define EMIT_CLOCKS(nsec) ((uint16_t)((nsec)   / 20))
+//#define EMIT_NSEC(clocks) ((uint16_t)((clocks) * 20))
+
+#if EMIT_PS == 0
+#define EMIT_CLOCKS(nsec) ((uint32_t)((nsec)   * 6 / 125))
+#define EMIT_NSEC(clocks) ((uint32_t)((clocks) * 125 / 6))
+#elif EMIT_PS == 1
+#define EMIT_CLOCKS(nsec) ((uint32_t)((nsec)   * 3 / 125))
+#define EMIT_NSEC(clocks) ((uint32_t)((clocks) * 125 / 3))
+#elif EMIT_PS == 2
+#define EMIT_CLOCKS(nsec) ((uint32_t)((nsec)   * 3 / 250))
+#define EMIT_NSEC(clocks) ((uint32_t)((clocks) * 250 / 3))
+#elif EMIT_PS == 3
+#define EMIT_CLOCKS(nsec) ((uint32_t)((nsec)   * 3 / 500))
+#define EMIT_NSEC(clocks) ((uint32_t)((clocks) * 500 / 3))
+#elif EMIT_PS == 4
+#define EMIT_CLOCKS(nsec) ((uint32_t)((nsec)   * 3 / 1000))
+#define EMIT_NSEC(clocks) ((uint32_t)((clocks) * 1000 / 3))
+#endif
+
+static uint32_t *emit_pcr    = 0; // transmit pin name
+
+static uint64_t  emit_start  = 0; // transmit start time (world time)
+static uint64_t  emit_period = 0; // transmit period
+static uint64_t  emit_due    = 0; // next transmit (world time)
+
+static uint32_t  emit_slack  = 0; // how far ahead we need to schedule, in us
+static uint32_t  emit_worst  = 0; // worst-case latency in task table
+
+void emit_init(int alt, PinName pin, PinMode mode)
+{
+       // Find pin
+       emit_pcr = (uint32_t*)(PORTA_BASE + pin);
+
+       // Enable clocks
+       SIM->SCGC6            |= SIM_SCGC6_TPM1_MASK;
+       SIM->SOPT2            |= SIM_SOPT2_TPMSRC(1);
+
+       // Reset PLL Source
+       //SIM->SOPT2 &= ~SIM_SOPT2_PLLFLLSEL_MASK;
+
+       // Debug print on SOPT2
+       // -- mbed may set PLLFLL when configuring UART0
+       // SOPT2: u0src=1 tpmsrc=1 USBSRC PLL/2 clkos=0 rtcos
+       sirq_printf("SOPT2: u0src=%d tpmsrc=%d %s %s clkos=%d %s\r\n",
+               (SIM->SOPT2 & SIM_SOPT2_UART0SRC_MASK)     >> SIM_SOPT2_UART0SRC_SHIFT,
+               (SIM->SOPT2 & SIM_SOPT2_TPMSRC_MASK)       >> SIM_SOPT2_TPMSRC_SHIFT,
+               (SIM->SOPT2 & SIM_SOPT2_UART0SRC_MASK)     ? "USBSRC" : "usbsrc",
+               (SIM->SOPT2 & SIM_SOPT2_PLLFLLSEL_MASK)    ? "PLL/2"  : "FLL",
+               (SIM->SOPT2 & SIM_SOPT2_CLKOUTSEL_MASK)    >> SIM_SOPT2_CLKOUTSEL_SHIFT,
+               (SIM->SOPT2 & SIM_SOPT2_RTCCLKOUTSEL_MASK) ? "RTCOS"  : "rtcos");
+
+       // Set pin mode
+       emit_pcr[0]            = PORT_PCR_ISF_MASK
+                              | PORT_PCR_MUX(alt)
+                              | mode;
+
+       // Setup Timer/PWM Module
+       TPM1->SC               = TPM_SC_TOF_MASK;
+       TPM1->CNT              = TPM_CNT_COUNT(0);
+       TPM1->MOD              = TPM_MOD_MOD(0xFFFF);
+
+       TPM1->CONTROLS[0].CnSC = TPM_CnSC_CHF_MASK    // clear flag
+                              | TPM_CnSC_MSB_MASK    // set output highon match,
+                              | TPM_CnSC_ELSB_MASK   // cleared on overflow
+                              | TPM_CnSC_ELSA_MASK;  // ..
+
+       TPM1->STATUS           = TPM_STATUS_CH0F_MASK
+                               | TPM_STATUS_TOF_MASK;
+
+       TPM1->CONF             = TPM_CONF_CSOO_MASK;
+}
+
+void emit_enable(uint64_t start, uint64_t period)
+{
+       const int slack_clocks = 0x4000; // tune based on emit_worst
+
+       emit_start  = start;
+       emit_period = period;
+       emit_due    = start + period;
+
+       emit_slack  = EMIT_NSEC(slack_clocks);
+
+       time_printf("emit scheduled", emit_due);
+}
+
+void emit_schedule(uint64_t when)
+{
+       uint64_t local  = time_to_local(when) * 3 / 125;
+       uint32_t width  = EMIT_CLOCKS(10000);
+
+       // Disable timer
+       TPM1->SC               = TPM_SC_TOF_MASK;
+
+       __disable_irq();
+
+       uint64_t now    = ((uint64_t)~PIT->LTMR64H << 32)
+                       | ((uint64_t)~PIT->LTMR64L);
+       uint32_t delta  = local - now;
+       uint32_t start  = delta >> (EMIT_PS-1); // convert to clocks
+       uint32_t stop   = start + width;        // end time
+
+       // Set transmit time
+       TPM1->CONTROLS[0].CnV  = start;
+       TPM1->MOD              = TPM_MOD_MOD(stop);
+
+       // Start the timer
+       TPM1->SC               = TPM_SC_TOF_MASK
+                              | TPM_SC_PS(EMIT_PS)
+                              | TPM_SC_CMOD(1);
+
+       __enable_irq();
+
+       // Test
+       //int64_t  cnv = TPM1->CONTROLS[0].CnV;
+       //int64_t  mod = TPM1->MOD;
+       //int64_t  due = local - tdma_time();
+       //sirq_printf("%6d -- cnv=%04x mod=%04x due=%04x start=%04x\r\n",
+       //              (int)(cnv - EMIT_CLOCKS(due)),
+       //              (int)cnv, (int)mod,
+       //              (int)EMIT_CLOCKS(due), EMIT_CLOCKS(start));
+
+       // Clock testing
+       //uint32_t test_tpm0 =  TPM1->CNT;
+       //uint32_t test_pit0 = ~PIT->CHANNEL[0].CVAL;
+       //for (int i = 0; i < 100; i++)
+       //      asm("nop");
+       //uint32_t test_tpm1 =  TPM1->CNT;
+       //uint32_t test_pit1 = ~PIT->CHANNEL[0].CVAL;
+
+       //uint32_t test_tpm  = test_tpm1 - test_tpm0;
+       //uint32_t test_pit  = test_pit1 - test_pit0;
+       //sirq_printf("pit/tpm: %d - tpm=%08x/%08x=%d pit=%08x/%08x=%d\r\n",
+       //              test_tpm - test_pit,
+       //              test_tpm0, test_tpm1, test_tpm,
+       //              test_pit0, test_pit1, test_pit);
+
+       // Debug output
+       //time_printf("emitting event", when);
+}
+
+void emit_transmit(uint64_t local, uint64_t world)
+{
+       static uint64_t prev = 0;
+
+       // Record how how much time we have to reschedule
+       if (prev && (local-prev) > emit_worst)
+               emit_worst = (local-prev);
+       prev = local;
+
+       // Schedule task if needed
+       if (emit_due && emit_period &&
+           world+emit_slack > emit_due) {
+               emit_schedule(emit_due);
+               emit_due += emit_period;
+       }
+}
+
+/************************
+ * Serial I/O functions *
+ ************************/
+
+typedef struct {
+       int      index;
+       int      state;
+       uint8_t  buffer[256];
+} parser_t;
+
+static uint32_t serial_device_id   = 0;
+
+const  uint64_t serial_sync_delay  = NSEC_PER_SEC / 100;
+static uint64_t serial_sync_due    = 0;
+
+static tdma_t  *serial_tdma_rcv    = NULL;
+static tdma_t  *serial_tdma_xmt    = NULL;
+
+/**
+ * Convert world to local time
+ */
+uint64_t serial_read_time(ntime_t time)
+{
+       return ((uint64_t)time.seconds) * NSEC_PER_SEC
+            + ((uint64_t)time.nanosec);
+}
+
+ntime_t serial_write_time(uint64_t time)
+{
+       ntime_t buf = {};
+       buf.seconds = time / NSEC_PER_SEC;
+       buf.nanosec = time % NSEC_PER_SEC;
+       return buf;
+}
+
+int serial_time_stamp(tdma_t *port, uint64_t *local, uint64_t *world,
+               const char *msg)
+{
+       int valid = tdma_stamp(port, local);
+       *world = time_to_world(*local);
+
+       if (!valid)
+               sirq_printf("%s -- missing\r\n", msg);
+       //else
+       //      time_printf(msg, current);
+
+       return valid;
+}
+
+/**
+ * Output initialization message init message
+ */
+void serial_send_init(uint16_t device, uint64_t local)
+{
+}
+
+/**
+ * Output time sync message
+ */
+void serial_send_sync(sirq_t *port, uint64_t now)
+{
+       if (serial_sync_due == 0 || now < serial_sync_due)
+               return; // not ready
+
+       // Message data
+       header_t   head;
+       sync_msg_t body;
+
+       // Write header
+       head.header = MSG_HEADER;
+       head.msgid  = MSG_ID_SYNC;
+       head.length = sizeof(body);
+       head.cksum  = 0; // todo
+
+       tdma_stop(serial_tdma_rcv, 0);
+       tdma_start(serial_tdma_xmt);
+
+       sirq_write(port, &head, sizeof(head));
+
+       tdma_stop(serial_tdma_xmt, 100);
+       tdma_start(serial_tdma_rcv);
+
+       // Save transmit time
+       uint64_t local = 0, world = 0;
+       serial_time_stamp(serial_tdma_xmt, &local, &world,
+                       "sync time transmit");
+
+       // Debug output
+       //sirq_printf("sync time transmit\r\n");
+       //time_printf("  local", local);
+       //time_printf("  world", world);
+
+       // Write body with updated time and send
+       body.time = serial_write_time(world);
+
+       sirq_write(port, &body, sizeof(body));
+
+       // Queue next transmit time
+       serial_sync_due  = 0;
+}
+
+/**
+ * Output external event received message
+ *   event: id of the received event
+ *   time:  compensated timestamp of the event
+ */
+void serial_send_event(sirq_t *port, uint16_t event, uint64_t local)
+{
+       //time_printf("event received", local);
+
+       // Convert timestamp
+       uint64_t world = time_to_world(local);
+       ntime_t  ltime = serial_write_time(local);
+       ntime_t  wtime = serial_write_time(world);
+
+       // Message data
+       header_t    head = {};
+       event_msg_t body = {};
+
+       // Transmit sync message
+       head.header = MSG_HEADER;
+       head.msgid  = MSG_ID_EVENT;
+       head.length = sizeof(body);
+       head.cksum  = 0; // todo
+
+       body.device = serial_device_id;
+       body.event  = event;
+       body.world  = wtime;
+       body.local  = ltime;
+
+       // Transmit message to BBB
+       sirq_write(port, &head, sizeof(head));
+       sirq_write(port, &body, sizeof(body));
+}
+
+/**
+ * Handle init message
+ */
+void serial_handle_init(init_msg_t *msg)
+{
+       sirq_printf("initialize: %s %s %s %s %s\r\n",
+               msg->valid & MSG_VALID_DEVICE ? "DEV"    : "dev",
+               msg->valid & MSG_VALID_START  ? "START"  : "start",
+               msg->valid & MSG_VALID_PERIOD ? "PERIOD" : "period",
+               msg->valid & MSG_VALID_WORLD  ? "WORLD"  : "world",
+               msg->valid & MSG_VALID_SYNC   ? "SYNC"   : "sync");
+       sirq_printf("  dev    -- %d\r\n", msg->device);
+       time_printf("  start ", serial_read_time(msg->start));
+       time_printf("  period", serial_read_time(msg->period));
+       time_printf("  world ", serial_read_time(msg->world));
+
+       if (msg->valid & MSG_VALID_DEVICE)
+               serial_device_id = msg->device;
+
+       if (msg->valid & MSG_VALID_START ||
+           msg->valid & MSG_VALID_PERIOD) {
+               uint64_t start  = serial_read_time(msg->start);
+               uint64_t period = serial_read_time(msg->period);
+               emit_enable(start, period);
+       }
+
+       if (msg->valid & MSG_VALID_WORLD) {
+               uint64_t world = serial_read_time(msg->world);
+               uint64_t local = tdma_time();
+               time_ext_init(local, world);
+       }
+
+       if (msg->valid & MSG_VALID_SYNC)
+               serial_sync_due = tdma_time() + serial_sync_delay;
+}
+
+/**
+ * Handle sync message
+ */
+void serial_handle_sync(sync_msg_t *msg)
+{
+       // Read receive timestamp
+       uint64_t local = 0, world = 0;
+       serial_time_stamp(serial_tdma_rcv, &local, &world,
+                       "sync time receive ");
+       tdma_stop(serial_tdma_rcv, 0);
+
+       // Lookup reference time from message
+       uint64_t reference = serial_read_time(msg->time);
+
+       // Debug output
+       //sirq_printf("sync time receive\r\n");
+       //time_printf("  local", local);
+       //time_printf("  world", world);
+       //time_printf("  ref  ", reference);
+
+       // Synchronize the clocks
+       time_ext_sync(local, reference);
+
+       // Queue transmit to other board
+       serial_sync_due   = tdma_time() + serial_sync_delay;
+}
+
+/**
+ * Handle event message
+ */
+void serial_handle_event(event_msg_t *msg)
+{
+}
+
+/**
+ * Deliver message
+ */
+void serial_deliver(int msgid, void *body)
+{
+       switch (msgid) {
+               case MSG_ID_INIT:
+                       //sirq_printf("received init msg\r\n");
+                       serial_handle_init((init_msg_t*)body);
+                       break;
+               case MSG_ID_SYNC:
+                       //sirq_printf("received sync msg\r\n");
+                       serial_handle_sync((sync_msg_t*)body);
+                       break;
+               case MSG_ID_EVENT:
+                       //sirq_printf("received event msg\r\n");
+                       serial_handle_event((event_msg_t*)body);
+                       break;
+       }
+}
+
+/**
+ * Process serial receive messages
+ */
+void serial_receive(parser_t *parser, int byte)
+{
+       //sirq_printf("serial_receive - %02x\r\n", byte);
+
+       // Lookup pointers
+       header_t *head = (header_t*)parser->buffer;
+       void     *body = (void*)(head+1);
+       const int max_length = sizeof(parser->buffer)-sizeof(header_t);
+
+       // Process uart messages
+       parser->buffer[parser->index++] = byte;
+       switch (parser->state) {
+               case 0: // Search
+                       if (parser->index == sizeof(uint16_t)) {
+                               if (head->header == MSG_HEADER) {
+                                       parser->state = 1;
+                               } else {
+                                       parser->buffer[0] = parser->buffer[1];
+                                       parser->index = 1;
+                               }
+                       }
+                       break;
+               case 1: // Header
+                       if (parser->index == sizeof(header_t)) {
+                               if (head->length <= max_length &&
+                                   head->msgid  <= MSG_MAX_ID) {
+                                       parser->state = 2;
+                               } else {
+                                       parser->index = 0;
+                                       parser->state = 0;
+                               }
+                       }
+                       break;
+               case 2: // Data
+                       if (parser->index == (int)sizeof(header_t)+head->length) {
+                               serial_deliver(head->msgid, body);
+                               parser->index = 0;
+                               parser->state = 0;
+                       }
+                       break;
+       }
+}
+
+/********************
+ * Data definitions *
+ ********************/
+
+// LEDs
+DigitalOut led1(LED1);
+DigitalOut led2(LED2);
+
+// Message Parsers
+parser_t   parser_dbg;
+parser_t   parser_bbb;
+parser_t   parser_mbed;
+
+// Serial IRQ
+sirq_t    *sirq_dbg;
+sirq_t    *sirq_bbb;
+sirq_t    *sirq_mbed;
+
+// Timer DMA
+tdma_t    *tdma_evt;
+tdma_t    *tdma_rcv;
+tdma_t    *tdma_xmt;
+
+/*********
+ * Tasks *
+ *********/
+
+void task_serial(uint64_t local, uint64_t world)
+{
+       while (sirq_ready(sirq_dbg)) {
+               //sirq_printf("serial recv - dbg\r\n");
+               serial_receive(&parser_dbg,  sirq_getc(sirq_dbg));
+       }
+
+       while (sirq_ready(sirq_bbb)) {
+               //sirq_printf("serial recv - bbb\r\n");
+               serial_receive(&parser_bbb,  sirq_getc(sirq_bbb));
+       }
+
+       while (sirq_ready(sirq_mbed)) {
+               //sirq_printf("serial recv - mbed\r\n");
+               serial_receive(&parser_mbed, sirq_getc(sirq_mbed));
+       }
+}
+
+void task_events(uint64_t local, uint64_t world)
+{
+       uint64_t event = 0;
+
+#ifdef VERBOSE
+       if (tdma_stamp(tdma_evt, &event)) {
+               sirq_printf("event received - evt\r\n");
+       if (tdma_stamp(tdma_rcv, &event))
+               sirq_printf("event received - rcv\r\n");
+       if (tdma_stamp(tdma_xmt, &event))
+               sirq_printf("event received - xmt\r\n");
+#endif
+
+       if (tdma_stamp(tdma_evt, &event))
+               serial_send_event(sirq_bbb, 0, event);
+       tdma_stop(tdma_evt, 0);
+       tdma_start(tdma_evt);
+}
+
+void task_sync(uint64_t local, uint64_t world)
+{
+       serial_send_sync(sirq_mbed, local);
+}
+
+void task_leds(uint64_t local, uint64_t world)
+{
+       static uint32_t which = 0;
+       led1 = (which == 0);
+       led2 = (which == 1);
+       which ^= 1;
+}
+
+void task_emit(uint64_t local, uint64_t world)
+{
+       emit_transmit(local, world);
+}
+
+void task_debug(uint64_t local, uint64_t world)
+{
+       //tdma_debug(tdma_rcv);
+       //tdma_debug(tdma_xmt);
+
+       //sirq_debug(sirq_mbed);
+
+       //serial_send_event(sirq_bbb, 1, local);
+
+#ifdef VERBOSE
+       sirq_printf("background - %6u.%02u -> %u.%02u\r\n",
+                       (uint32_t)(local / NSEC_PER_SEC),
+                       (uint32_t)(local % NSEC_PER_SEC / 10000000),
+                       (uint32_t)(world / NSEC_PER_SEC),
+                       (uint32_t)(world % NSEC_PER_SEC / 10000000));
+#endif
+}
+
+/********
+ * Main *
+ ********/
+
+#define N_ELEM(x) (sizeof(x) / sizeof((x)[0]))
+
+extern void test_main(void);
+extern serial_t stdio_uart;
+
+static struct {
+       void (*task)(uint64_t, uint64_t);
+       uint64_t period;
+       uint64_t due;
+} tasks[] = {
+       { task_serial, 0          }, // always
+       { task_events, 0          }, // always -- testing
+       { task_sync,   0          }, // always
+       { task_emit,   0          }, // always
+       { task_leds,   100000000  }, // 10hz
+       { task_debug,  1000000000 }, // 1hz
+};
+
+void background(void)
+{
+       // Debugging
+       uint64_t local = tdma_time();
+       uint64_t world = time_to_world(local);
+
+       // Run the scheduler
+       for (unsigned i = 0; i < N_ELEM(tasks); i++) {
+               if (local >= tasks[i].due) {
+                       tasks[i].task(local, world);
+                       tasks[i].due += tasks[i].period;
+               }
+       }
+}
+
+int main(int argc, char **argv)
+{
+       tdma_init();
+
+       //pin = 1;
+
+       // Open serial ports
+       sirq_dbg   = sirq_open(SIRQ_UART0, USBTX, USBRX, 115200); // to pc
+       sirq_bbb   = sirq_open(SIRQ_UART1, PTE0,  PTE1,  115200); // to bbb
+       sirq_mbed  = sirq_open(SIRQ_UART2, PTD3,  PTD2,  115200); // to mbed
+
+       // Setup timers
+       tdma_evt   = tdma_open(TDMA_CHAN0, 3, PTC9,  PullDown); // async event
+
+       // mbed time sync
+       tdma_rcv   = tdma_open(TDMA_CHAN2, 3, PTD2,  PullUp);   // time sync rcv
+       tdma_xmt   = tdma_open(TDMA_CHAN3, 3, PTD3,  PullUp);   // time sync xmt
+
+       // host time sync
+       //tdma_rcv   = tdma_open(TDMA_CHAN2, 2, USBRX, PullUp); // time sync rcv
+       //tdma_xmt   = tdma_open(TDMA_CHAN3, 2, USBTX, PullUp); // time sync xmt
+
+       // start timers
+       tdma_start(tdma_evt);
+       tdma_start(tdma_rcv);
+       tdma_start(tdma_xmt);
+
+       // Serial timestamping
+       serial_tdma_rcv = tdma_rcv;
+       serial_tdma_xmt = tdma_xmt;
+
+       // Setup event generation
+       emit_init(3, PTE20, PullDown);
+
+       // Run background loop
+       while (true)
+               background();
+
+       // Run tests
+       //test_main();
+
+       return 0;
+}