fix ems line quality calculation

Author: proddy

src/emsesp.cpp

@@ -196,19 +196,21 @@ uint8_t EMSESP::bus_status() {
     // check if we have Tx issues.
     uint32_t total_sent = txservice_.telegram_read_count() + txservice_.telegram_write_count();
 
-    // nothing sent successfully, also no errors - must be ok
+    // nothing sent and also no errors - must be ok
     if ((total_sent == 0) && (txservice_.telegram_fail_count() == 0)) {
         return BUS_STATUS_CONNECTED;
     }
 
-    // nothing sent successfully, but have Tx errors
+    // nothing sent, but have Tx errors
     if ((total_sent == 0) && (txservice_.telegram_fail_count() != 0)) {
         return BUS_STATUS_TX_ERRORS;
     }
 
-    // Tx Failure rate > 5%
-    if (((txservice_.telegram_fail_count() * 100) / total_sent) > EMSbus::EMS_TX_ERROR_LIMIT) {
-        return BUS_STATUS_TX_ERRORS;
+    // Tx Failure rate > 10%
+    if (txservice_.telegram_fail_count() < total_sent) {
+        if (((txservice_.telegram_fail_count() * 100) / total_sent) > EMSbus::EMS_TX_ERROR_LIMIT) {
+            return BUS_STATUS_TX_ERRORS;
+        }
     }
 
     return BUS_STATUS_CONNECTED;

src/telegram.h

@@ -218,7 +218,11 @@ class RxService : public EMSbus {
         if (telegram_error_count_ == 0) {
             return 100; // all good, 100%
         }
+        if (telegram_error_count_ >= telegram_count_) {
+            return 100;
+        }
         uint8_t q = ((float)telegram_error_count_ / telegram_count_ * 100);
+
         return (q <= EMS_BUS_QUALITY_RX_THRESHOLD ? 100 : 100 - q);
     }
 
@@ -308,6 +312,9 @@ class TxService : public EMSbus {
         if (telegram_fail_count_ == 0) {
             return 100; // all good, 100%
         }
+        if (telegram_fail_count_ >= telegram_read_count_) {
+            return 100;
+        }
         return (100 - (uint8_t)(((float)telegram_fail_count_ / telegram_read_count_ * 100)));
     }