From e34137582d4589c1cf3be2d2f59b060e053dac63 Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Sat, 14 Aug 2021 13:41:12 -0400
Subject: adxl345: Implement timing via new adxl345_status messages

Query the adxl345 message counter every 100ms so that accurate timing
can be obtained during measurements.  This allows the adxl345 data to
be exported with timestamps while captures are running.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
---
 src/sensor_adxl345.c | 62 ++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 43 insertions(+), 19 deletions(-)

(limited to 'src')

diff --git a/src/sensor_adxl345.c b/src/sensor_adxl345.c
index 1e2cb9e5..309b3ff1 100644
--- a/src/sensor_adxl345.c
+++ b/src/sensor_adxl345.c
@@ -27,6 +27,7 @@ enum {
 
 static struct task_wake adxl345_wake;
 
+// Event handler that wakes adxl345_task() periodically
 static uint_fast8_t
 adxl345_event(struct timer *timer)
 {
@@ -56,6 +57,27 @@ adxl_report(struct adxl345 *ax, uint8_t oid)
     ax->sequence++;
 }
 
+// Report buffer and fifo status
+static void
+adxl_status(struct adxl345 *ax, uint_fast8_t oid
+            , uint32_t time1, uint32_t time2, uint_fast8_t fifo)
+{
+    sendf("adxl345_status oid=%c clock=%u query_ticks=%u next_sequence=%hu"
+          " buffered=%c fifo=%c limit_count=%hu"
+          , oid, time1, time2-time1, ax->sequence
+          , ax->data_count, fifo, ax->limit_count);
+}
+
+// Helper code to reschedule the adxl345_event() timer
+static void
+adxl_reschedule_timer(struct adxl345 *ax)
+{
+    irq_disable();
+    ax->timer.waketime = timer_read_time() + ax->rest_ticks;
+    sched_add_timer(&ax->timer);
+    irq_enable();
+}
+
 // Chip registers
 #define AR_POWER_CTL   0x2D
 #define AR_DATAX0      0x32
@@ -74,7 +96,7 @@ adxl_query(struct adxl345 *ax, uint8_t oid)
     if (ax->data_count + 6 > ARRAY_SIZE(ax->data))
         adxl_report(ax, oid);
     uint_fast8_t fifo_status = msg[8] & ~0x80; // Ignore trigger bit
-    if (fifo_status >= 31 && ax->limit_count != 0xffff)
+    if (fifo_status >= 31)
         ax->limit_count++;
     if (fifo_status > 1 && fifo_status <= 32) {
         // More data in fifo - wake this task again
@@ -83,10 +105,7 @@ adxl_query(struct adxl345 *ax, uint8_t oid)
         // Sleep until next check time
         sched_del_timer(&ax->timer);
         ax->flags &= ~AX_PENDING;
-        irq_disable();
-        ax->timer.waketime = timer_read_time() + ax->rest_ticks;
-        sched_add_timer(&ax->timer);
-        irq_enable();
+        adxl_reschedule_timer(ax);
     }
 }
 
@@ -97,15 +116,8 @@ adxl_start(struct adxl345 *ax, uint8_t oid)
     sched_del_timer(&ax->timer);
     ax->flags = AX_RUNNING;
     uint8_t msg[2] = { AR_POWER_CTL, 0x08 };
-    uint32_t start1_time = timer_read_time();
     spidev_transfer(ax->spi, 0, sizeof(msg), msg);
-    irq_disable();
-    uint32_t start2_time = timer_read_time();
-    ax->timer.waketime = start2_time + ax->rest_ticks;
-    sched_add_timer(&ax->timer);
-    irq_enable();
-    sendf("adxl345_start oid=%c start1_clock=%u start2_clock=%u"
-          , oid, start1_time, start2_time);
+    adxl_reschedule_timer(ax);
 }
 
 // End measurements
@@ -123,18 +135,18 @@ adxl_stop(struct adxl345 *ax, uint8_t oid)
     uint_fast8_t i;
     for (i=0; i<33; i++) {
         msg[0] = AR_FIFO_STATUS | AM_READ;
-        msg[1] = 0;
+        msg[1] = 0x00;
         spidev_transfer(ax->spi, 1, sizeof(msg), msg);
-        if (!(msg[1] & 0x3f))
+        uint_fast8_t fifo_status = msg[1] & ~0x80;
+        if (!fifo_status)
             break;
-        adxl_query(ax, oid);
+        if (fifo_status <= 32)
+            adxl_query(ax, oid);
     }
     // Report final data
     if (ax->data_count)
         adxl_report(ax, oid);
-    sendf("adxl345_end oid=%c end1_clock=%u end2_clock=%u"
-          " limit_count=%hu sequence=%hu"
-          , oid, end1_time, end2_time, ax->limit_count, ax->sequence);
+    adxl_status(ax, oid, end1_time, end2_time, msg[1]);
 }
 
 void
@@ -159,6 +171,18 @@ command_query_adxl345(uint32_t *args)
 DECL_COMMAND(command_query_adxl345,
              "query_adxl345 oid=%c clock=%u rest_ticks=%u");
 
+void
+command_query_adxl345_status(uint32_t *args)
+{
+    struct adxl345 *ax = oid_lookup(args[0], command_config_adxl345);
+    uint8_t msg[2] = { AR_FIFO_STATUS | AM_READ, 0x00 };
+    uint32_t time1 = timer_read_time();
+    spidev_transfer(ax->spi, 1, sizeof(msg), msg);
+    uint32_t time2 = timer_read_time();
+    adxl_status(ax, args[0], time1, time2, msg[1]);
+}
+DECL_COMMAND(command_query_adxl345_status, "query_adxl345_status oid=%c");
+
 void
 adxl345_task(void)
 {
-- 
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