From 5416debc9822119e77f8c8a1d482faa50060c69d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Hru=C5=A1ka?= <ondra@ondrovo.com>
Date: Sun, 2 Jan 2022 23:44:37 +0100
Subject: [PATCH] better error reporting for co2

---
 main/co2_sensor.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/main/co2_sensor.c b/main/co2_sensor.c
index ed47a15..c3f8f19 100644
--- a/main/co2_sensor.c
+++ b/main/co2_sensor.c
@@ -36,6 +36,10 @@ static int mb_write_and_read(uint8_t *buffer, int num, size_t resplen) {
     num = uart_read_bytes(CO2_UART_NUM, buffer, resplen, pdMS_TO_TICKS(500));
     ESP_LOGD(TAG, "Received %d bytes", num);
     ESP_LOG_BUFFER_HEXDUMP(TAG, buffer, num, ESP_LOG_DEBUG);
+
+    if (num == 0) {
+        ESP_LOGE(TAG, "No modbus response!");
+    }
     return num;
 }