From 7a83a06c922b5554830624173b7f11b45fe99b2d Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Thu, 20 Dec 2018 17:12:59 +1100
Subject: [PATCH] esptool: Add some clarification if list_ports is missing

Closes https://github.com/espressif/esptool/issues/350

Also fixes regression in detecting wrong 'serial' module (see https://github.com/espressif/esptool/issues/269)
---
 esptool.py | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/esptool.py b/esptool.py
index 337883c28..6cd33d378 100755
--- a/esptool.py
+++ b/esptool.py
@@ -32,9 +32,12 @@
 import time
 import zlib
 import string
-import serial.tools.list_ports as list_ports
 
-import serial
+try:
+    import serial
+except ImportError:
+    print("Pyserial is not installed for %s. Check the README for installation instructions." % (sys.executable))
+    raise
 
 # check 'serial' is 'pyserial' and not 'serial' https://github.com/espressif/esptool/issues/269
 try:
@@ -50,6 +53,12 @@
 except TypeError:
     pass  # __doc__ returns None for pyserial
 
+try:
+    import serial.tools.list_ports as list_ports
+except ImportError:
+    print("The installed version (%s) of pyserial appears to be too old for esptool.py (Python interpreter %s). "
+          "Check the README for installation instructions." % (sys.VERSION, sys.executable))
+    raise
 
 __version__ = "2.6-beta1"