Fix #30, flush() for STM32 (#31)

- Fix #30, improve **flush()** to work for STM32
- add **void setMicrosPerByte(mpb)** to set delay after flush() for last byte.
- add **uint16_t getMicrosPerByte()**
- update GitHub actions
- minor edits

CHANGELOG.md

@@ -6,6 +6,14 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.5.1] - 2024-04-04
+- improve **flush()** to work for STM32
+- add **void setMicrosPerByte(mpb)** to set delay after flush() for last byte.
+- add **uint16_t getMicrosPerByte()**
+- update GitHub actions
+- minor edits
+
+
 ## [0.5.0] - 2024-02-01
 - merge PR #28, Fix for FS conflict on ESP32 (kudos to DoomHammer)
   - all ASCII control characters get a **ASCII_** prefix.

README.md

@@ -107,6 +107,20 @@ An important command from the stream interface is the **setTimeOut()** as
 this allows reads on the RS485 bus that are limited.
 
 
+#### setMicrosPerByte
+
+**Experimental**
+
+To add a small delay after **flush()** to be sure that the last byte in the 
+TX register has time to be sent.
+It prevents a premature switching from transmit to receive mode.
+The default value is 1100 (9600 baud time) and can be tuned, e.g. when high 
+baud rates are used it can be smaller.
+
+- **void setMicrosPerByte(uint16_t mpb)**
+- **uint16_t getMicrosPerByte()** returns set value, default 1100 (9600 baud time).
+
+
 #### Experimental
 
 Work in progress. The library has an **experimental** protocol implemented to
@@ -223,6 +237,7 @@ Would allow 127 different 1 byte commands.
   - dynamic receive buffer size?
 - investigate error handling?
 - test other platforms
+  - STM32 (see issue 30)
   - ESP32.
 
 #### Could
@@ -232,6 +247,7 @@ Would allow 127 different 1 byte commands.
   - multi-master?
 - add unit tests
 - investigate yield() on ESP32/RTOS behaviour
+- investigate non-blocking version.
 
 #### Wont
 

RS485.cpp

@@ -2,7 +2,7 @@
 //    FILE: RS485.cpp
 //  AUTHOR: Rob Tillaart
 //    DATE: 30-okt-2017
-// VERSION: 0.5.0
+// VERSION: 0.5.1
 // PURPOSE: Arduino library for RS485 modules (MAX485)
 //     URL: https://github.com/RobTillaart/RS485
 
@@ -55,7 +55,12 @@ int RS485::peek()
 
 void RS485::flush()
 {
+#ifdef ARDUINO_ARCH_STM32
+  while (Serial.availableForWrite() < ( SERIAL_TX_BUFFER_SIZE - 1));
+#else
   _stream->flush();
+#endif
+  delayMicroseconds(_microsPerByte);  //  for the last byte.
 }
 
 

RS485.h

@@ -3,15 +3,15 @@
 //    FILE: RS485.h
 //  AUTHOR: Rob Tillaart
 //    DATE: 30-okt-2017
-// VERSION: 0.5.0
+// VERSION: 0.5.1
 // PURPOSE: Arduino library for RS485 modules
 //     URL: https://github.com/RobTillaart/RS485
 
 
 #include "Arduino.h"
 #include "ASCII_CONTROL.h"
 
-#define RS485_LIB_VERSION        (F("0.5.0"))
+#define RS485_LIB_VERSION        (F("0.5.1"))
 
 
 class RS485 : public Stream
@@ -47,19 +47,23 @@ class RS485 : public Stream
   //  send ASCII encoded messages from one master to multiple clients.
   //       msg[] = 32..127
   //       len   =  1.. 48 (internal receive buffer is 50)
-  size_t  send(uint8_t receiverID, uint8_t msg[], uint8_t len);
-  bool    receive(uint8_t &senderID, uint8_t msg[], uint8_t &len);
+  size_t   send(uint8_t receiverID, uint8_t msg[], uint8_t len);
+  bool     receive(uint8_t &senderID, uint8_t msg[], uint8_t &len);
 
   //  EXPERIMENTAL
-  size_t  send(uint8_t receiverID, char msg[], uint8_t len);
-  bool    receive(uint8_t &senderID, char msg[], uint8_t &len);
+  size_t   send(uint8_t receiverID, char msg[], uint8_t len);
+  bool     receive(uint8_t &senderID, char msg[], uint8_t &len);
+
+  //  EXPERIMENTAL
+  void     setMicrosPerByte(uint16_t mpb) { _microsPerByte = mpb; };
+  uint16_t getMicrosPerByte() { return _microsPerByte; };
 
 
 private:
   Stream   * _stream;
   uint8_t  _sendPin       = 0;
   uint8_t  _deviceID      = 0;
-  uint16_t _microsPerByte = 1000;
+  uint16_t _microsPerByte = 1100;
 
   //       EXPERIMENTAL
   uint8_t _bidx = 0;

examples/RS485_SWS_master_send_receive/RS485_SWS_master_send_receive.ino

@@ -23,7 +23,7 @@
 const uint8_t sendPin  = 4;
 const uint8_t deviceID = 0;
 
-SoftwareSerial SWS(6,7);  //  RX, TX
+SoftwareSerial SWS(6, 7);  //  RX, TX
 
 
 //  use Software Serial

examples/RS485_performance/RS485_performance.ino

@@ -6,6 +6,7 @@
 //  minimal test to see how fast data can be send over the
 //  RS485 bus at a given baud rate of 4800. (adjust if needed).
 
+
 #include "Arduino.h"
 #include "RS485.h"
 

examples/RS485_sniffer/RS485_sniffer.ino

@@ -73,7 +73,7 @@ void loop()
 
     int x = rs485.read();
 
-    // HEX DUMP PART
+    //  HEX DUMP PART
     if (x < 0x10) Serial.print('0');
     Serial.print(x, HEX);
     Serial.print(" ");

library.json

@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/RS485"
   },
-  "version": "0.5.0",
+  "version": "0.5.1",
   "license": "MIT",
   "frameworks": "*",
   "platforms": "*",

library.properties

@@ -1,5 +1,5 @@
 name=RS485
-version=0.5.0
+version=0.5.1
 author=Rob Tillaart <[email protected]>
 maintainer=Rob Tillaart <[email protected]>
 sentence=RS485 library for Arduino.