From 6417b59a30e8445e72aa8616e6403542eee30912 Mon Sep 17 00:00:00 2001
From: Lee Ballard <ballle98@gmail.com>
Date: Fri, 3 Nov 2023 16:02:40 -0500
Subject: [PATCH] ballle98/AqualinkD#87: loopover_devices :- can't goto
 PM_EQUIPTMENT_CONTROL menu

---
 Makefile            |  5 +++--
 aq_serial.c         | 28 ++++++++++++++++++++++++++++
 timespec_subtract.c |  2 +-
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index f63173b6..d7a518fb 100755
--- a/Makefile
+++ b/Makefile
@@ -74,7 +74,7 @@ endif
 # Main source files
 SRCS = aqualinkd.c utils.c config.c aq_serial.c aq_panel.c aq_programmer.c net_services.c json_messages.c rs_msg_utils.c\
        devices_jandy.c packetLogger.c devices_pentair.c color_lights.c serialadapter.c aq_timer.c aq_scheduler.c web_config.c\
-       serial_logger.c mongoose.c
+       serial_logger.c mongoose.c timespec_subtract.c
 
 
 AQ_FLAGS =
@@ -128,7 +128,8 @@ DBG_CFLAGS = $(DBGFLAGS) $(AQ_FLAGS) $(MGFLAGS)
 
 # Other sources.
 DBG_SRC = $(SRCS) debug_timer.c
-SL_SRC = serial_logger.c aq_serial.c utils.c packetLogger.c rs_msg_utils.c
+SL_SRC = serial_logger.c aq_serial.c utils.c packetLogger.c rs_msg_utils.c \
+	timespec_subtract.c
 
 # Build durectories
 OBJ_DIR := ./build
diff --git a/aq_serial.c b/aq_serial.c
index 66b4f276..5edc42f1 100644
--- a/aq_serial.c
+++ b/aq_serial.c
@@ -30,6 +30,7 @@
 #include "utils.h"
 #include "config.h"
 #include "packetLogger.h"
+#include "timespec_subtract.h"
 
 /*
 Notes for serial usb speed 
@@ -52,6 +53,8 @@ int _blocking_fds = -1;
 
 static struct termios _oldtio;
 
+static struct timespec last_serial_read_time;
+
 void send_packet(int fd, unsigned char *packet, int length);
 //unsigned char getProtocolType(unsigned char* packet);
 
@@ -725,6 +728,25 @@ void send_packet(int fd, unsigned char *packet_buffer, int length)
 void send_packet(int fd, unsigned char *packet, int length)
 {
 #endif
+  struct timespec elapsed_time;
+  struct timespec now;
+  struct timespec min_frame_wait_time = {0, 4000000}; // 4 milliseconds
+  struct timespec frame_wait_time;
+  struct timespec remainder_time;
+
+  // No spec for aqualink protocol but looking at similar RS-485 protocol
+  // https://www.tascam.eu/en/docs/MX-8A_RS-485_protocol.pdf there is a
+  // min frame to frame time of 4 milliseconds and there seems to be issues
+  // with RPi 4 sending a response too quickly
+  do {
+    clock_gettime(CLOCK_REALTIME, &now);
+    timespec_subtract(&elapsed_time, &now, &last_serial_read_time);
+    if (timespec_subtract(&frame_wait_time, &min_frame_wait_time, &elapsed_time)) {
+      break;
+    }
+  } while (nanosleep(&frame_wait_time, &remainder_time) != 0);
+
+  clock_gettime(CLOCK_REALTIME, &now);
 
   if (_blocking_mode) {
     //int nwrite = write(fd, packet, length);
@@ -783,6 +805,11 @@ void send_packet(int fd, unsigned char *packet, int length)
   }*/
 
   tcdrain(fd); // Make sure buffer has been sent.
+  timespec_subtract(&elapsed_time, &now, &last_serial_read_time);
+  LOG(RSSD_LOG, LOG_DEBUG, "Time from recv to %s send is %ld.%09ld sec\n",
+    (_blocking_mode?"blocking":"non-blocking"), elapsed_time.tv_sec,
+    elapsed_time.tv_nsec);
+
 }
 
 void _send_ack(int fd, unsigned char ack_type, unsigned char command)
@@ -1032,6 +1059,7 @@ int get_packet(int fd, unsigned char* packet)
     return AQSERR_2SMALL;
   }
 
+  clock_gettime(CLOCK_REALTIME, &last_serial_read_time);
   LOG(RSSD_LOG,LOG_DEBUG_SERIAL, "Serial read %d bytes\n",index);
   if (_aqconfig_.log_protocol_packets || getLogLevel(RSSD_LOG) >= LOG_DEBUG_SERIAL)
     logPacketRead(packet, index);
diff --git a/timespec_subtract.c b/timespec_subtract.c
index bff19179..361a83bb 100644
--- a/timespec_subtract.c
+++ b/timespec_subtract.c
@@ -8,7 +8,7 @@
  */
 
 
-/* Based on https://www.gnu.org/software/libc/manual/html_node/Elapsed-Time.html
+/* Based on https://www.gnu.org/software/libc/manual/html_node/Calculating-Elapsed-Time.html
    Subtract the struct timespec values X and Y,
    storing the result in RESULT.
    Return 1 if the difference is negative, otherwise 0. */