From 3b2818f150f8e3d1d0880bf6a520a870f703f149 Mon Sep 17 00:00:00 2001
From: Elia Marcinkiewicz <elia@marcinkiewicz.me>
Date: Fri, 28 Jul 2023 22:07:51 +0200
Subject: [PATCH] add separate PN532 exception handling, print exception
 messages

---
 esp32/main.py  |  6 ++++--
 esp32/pn532.py | 25 ++++++++++++++-----------
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/esp32/main.py b/esp32/main.py
index 87b2838..62a9721 100644
--- a/esp32/main.py
+++ b/esp32/main.py
@@ -1,4 +1,4 @@
-from pn532 import PN532Uart
+from pn532 import PN532Uart, PN532Error
 import utime
 import machine
 import hashlib
@@ -52,5 +52,7 @@ while rf is not None:
             uart.write("FS")
         utime.sleep(2)
         buf=''
+    except PN532Error as e:
+        print('PN532:', e)
     except Exception as e:
-        print('timeout!')
+        print(e)
diff --git a/esp32/pn532.py b/esp32/pn532.py
index c92d2c8..0b5c264 100644
--- a/esp32/pn532.py
+++ b/esp32/pn532.py
@@ -27,6 +27,9 @@ _FRAME_START                   = b'\x00\x00\xFF'
 # Codes
 _MIFARE_ISO14443A              = const(0x00)
 
+class PN532Error(RuntimeError):
+    pass
+
 class PN532Uart(object):
     """
     Class for interacting with the PN532 via the uart interface.
@@ -49,7 +52,7 @@ class PN532Uart(object):
             continue
 
         if(utime.ticks_ms() >= end_time):
-            raise RuntimeError('No response from PN532!')
+            raise PN532Error('No response from PN532!')
 
         return self.uart.read(len)
 
@@ -103,7 +106,7 @@ class PN532Uart(object):
         if self.debug:
             print('_write_frame: ACK: ', [hex(i) for i in ack])
         if ack != _ACK:
-            raise RuntimeError('Did not receive expected ACK from PN532!')
+            raise PN532Error('Did not receive expected ACK from PN532!')
 
     def _read_frame(self):
         """
@@ -116,13 +119,13 @@ class PN532Uart(object):
             print('_read_frame: frame_start + header:', [hex(i) for i in response])
 
         if len(response) < (len(_FRAME_START) + 2) or response[:-2] != _FRAME_START:
-            raise RuntimeError('Response does not begin with _FRAME_START!')
+            raise PN532Error('Response does not begin with _FRAME_START!')
 
         # Read the header (length & length checksum) and make sure they match.
         frame_len = response[-2]
         frame_checksum = response[-1]
         if (frame_len + frame_checksum) & 0xFF != 0:
-            raise RuntimeError('Response length checksum did not match length!')
+            raise PN532Error('Response length checksum did not match length!')
 
         # read the frame (data + data checksum + end frame) & validate
         data = self.wait_read_len(frame_len+2)
@@ -132,10 +135,10 @@ class PN532Uart(object):
 
         checksum = sum(data) & 0xFF
         if checksum != 0:
-            raise RuntimeError('Response checksum did not match expected value: ', checksum)
+            raise PN532Error('Response checksum did not match expected value: ', checksum)
 
         if data[-1] != 0x00:
-            raise RuntimeError('Response does not include Frame End')
+            raise PN532Error('Response does not include Frame End')
 
         # Return frame data.
         return data[0:frame_len]
@@ -156,10 +159,10 @@ class PN532Uart(object):
         response = self._read_frame()
 
         if len(response) < 2:
-            raise RuntimeError('Received smaller than expected frame')
+            raise PN532Error('Received smaller than expected frame')
 
         if not(response[0] == _PN532TOHOST and response[1] == (command+1)):
-            raise RuntimeError('Received unexpected command response!')
+            raise PN532Error('Received unexpected command response!')
 
         # Return response data.
         return response[2:]
@@ -182,7 +185,7 @@ class PN532Uart(object):
 
         response = self.call_function(_COMMAND_GETFIRMWAREVERSION)
         if response is None:
-            raise RuntimeError('Failed to detect the PN532')
+            raise PN532Error('Failed to detect the PN532')
         return tuple(response)
 
     def read_passive_target(self, card_baud=_MIFARE_ISO14443A):
@@ -198,9 +201,9 @@ class PN532Uart(object):
 
         # Check only 1 card with up to a 7 byte UID is present.
         if response[0] != 0x01:
-            raise RuntimeError('More than one card detected!')
+            raise PN532Error('More than one card detected!')
         if response[5] > 7:
-            raise RuntimeError('Found card with unexpectedly long UID!')
+            raise PN532Error('Found card with unexpectedly long UID!')
 
         # Return UID of card.
         return response[6:6+response[5]]